ABSTRACT: Root-knot nematodes (RKNs) are ubiquitous parasites with an amazing capacity to interact with a very large variety of plant species. They are sedentary endoparasitic nematodes that depend on the induction of a permanent feeding site in living roots to complete their life cycle. RKNs interfere with the genetic programmes of their hosts to transform root vascular cells into giant cells (GCs) through the injection of nematode effectors from their oesophageal glands. Dramatic rearrangements in GCs cytoskeleton, alteration of cell cycle mechanisms, such as mitosis and endoreduplication, readjustment of enzymes involved in carbohydrate synthesis and degradation are among those processes modified in GCs. GCs act as sinks to provide nutrients for life cycle completion from J2 larvae to adult females. The female produces an egg offspring protected by a gelatinous matrix and the free-living stage, J2, hatch from these eggs, completing the nematode life cycle. The understanding of the processes subjacent to GC differentiation and maintenance, as well as a deeper knowledge of RKN mode of parasitism, will provide tools for new control methods of these devastating agricultural pests.
Host range of mungbean yellow mosaic virus (mymv) and influence of age of see...Jayappa Singanodi
Among twelve different plant species belonging to two families viz. Leguminosae and Solanaceae, only leguminous crops such as soybean (Glycin max (L.) Merr.), Pigeonpea (Cajanuscajan (L.) Millsp.), Black gram (Vigna mungo (L.) Hepper), Horse gram (Macrotyloma uniflorum (Lam.) Verdc.) and French bean (Phaseolus vulgaris L.) were transmitted with MYMV. Seedlings with early inoculation recorded highest per cent transmission. 93.33 per cent transmission was recorded in ten days old seedlings followed 80, 66.66, 46.66 and 33.33 per cent transmission were recorded by 15, 20, 25 and 30 days old seedlings, respectively.
1. The document discusses the role of wild relatives in providing host plant resistance to rice and sorghum crops against various pests and diseases.
2. In rice, Oryza nivara provides resistance to brown planthopper in Sri Lanka. Oryza glaberrima shows resistance to gall midge in Africa. Wild species like O. brachyantha, O. rufipogon and O. meridionalis show resistance to leaf folder in Pakistan.
3. In sorghum, wild relatives like heterosorghum, parasorghum and stiposorghum show less damage from spotted stem borer compared to cultivated varieties in India. Wild sorg
Ecology of plant parasitic nematode’s (PPN's)Francis Matu
This document provides an overview of the ecology of plant-parasitic nematodes (PPNs). It defines key ecological concepts and describes various aspects of PPN ecology, including population ecology, community and ecosystem interactions, the soil food web, physical habitat factors, foraging patterns, niche partitioning, and the role of PPNs in ecosystem functions like primary productivity, decomposition, and nutrient cycling.
HPR IN MANAGEMENT OF SORGHUM FOLIAR DISEASESUmesh b s
The document discusses host plant resistance in sorghum for foliar diseases. It provides background on sorghum as a drought-tolerant cereal crop and identifies important foliar diseases like anthracnose, leaf blight, and rust. It then defines host plant resistance and describes different types of genetic resistance including vertical, horizontal, monogenic, and polygenic resistance. The document outlines a study conducted at ICRISAT, Hyderabad where a sorghum mini-core collection was evaluated for resistance to foliar diseases, identifying sources of resistance.
Nematode populations dynamics threshold levels and estimation ofFrancis Matu
This document discusses nematode population dynamics, threshold levels, and crop loss estimation. It outlines factors that influence nematode thresholds, such as pathogens, soil type, plant vigor, temperature, and antagonistic microbes. The document also describes nematode population dynamics, noting that some species are K-strategists with low reproduction rates while others are r-strategists that can rapidly increase populations when conditions are favorable. Models for estimating nematode multiplication rates are presented, accounting for variables like the maximum reproduction rate and equilibrium population density. Approaches for assessing yield losses from nematodes, including damage models, are also mentioned.
Effects of Chemical Constituents on Insect Pest Population in West African Ok...IOSR Journals
This study examined the effects of chemical constituents on insect pest populations in different genotypes of West African okra (Abelmoschus caillei). Six genotypes were obtained from a germplasm collection and evaluated in a field experiment. Results showed that three genotypes (NGAE-96-0067, NGAE-96-0123, and CEN 10) attracted fewer insects, had lower leaf and pod damage, and contained higher levels of chemical constituents that conferred resistance to insects. These three genotypes are recommended for farmers despite insect attacks due to their economic value. A positive correlation was found between insect damage and reduced seed yield, indicating that insect resistance is important for okra production. The study concluded that antixen
Host range of mungbean yellow mosaic virus (mymv) and influence of age of see...Jayappa Singanodi
Among twelve different plant species belonging to two families viz. Leguminosae and Solanaceae, only leguminous crops such as soybean (Glycin max (L.) Merr.), Pigeonpea (Cajanuscajan (L.) Millsp.), Black gram (Vigna mungo (L.) Hepper), Horse gram (Macrotyloma uniflorum (Lam.) Verdc.) and French bean (Phaseolus vulgaris L.) were transmitted with MYMV. Seedlings with early inoculation recorded highest per cent transmission. 93.33 per cent transmission was recorded in ten days old seedlings followed 80, 66.66, 46.66 and 33.33 per cent transmission were recorded by 15, 20, 25 and 30 days old seedlings, respectively.
1. The document discusses the role of wild relatives in providing host plant resistance to rice and sorghum crops against various pests and diseases.
2. In rice, Oryza nivara provides resistance to brown planthopper in Sri Lanka. Oryza glaberrima shows resistance to gall midge in Africa. Wild species like O. brachyantha, O. rufipogon and O. meridionalis show resistance to leaf folder in Pakistan.
3. In sorghum, wild relatives like heterosorghum, parasorghum and stiposorghum show less damage from spotted stem borer compared to cultivated varieties in India. Wild sorg
Ecology of plant parasitic nematode’s (PPN's)Francis Matu
This document provides an overview of the ecology of plant-parasitic nematodes (PPNs). It defines key ecological concepts and describes various aspects of PPN ecology, including population ecology, community and ecosystem interactions, the soil food web, physical habitat factors, foraging patterns, niche partitioning, and the role of PPNs in ecosystem functions like primary productivity, decomposition, and nutrient cycling.
HPR IN MANAGEMENT OF SORGHUM FOLIAR DISEASESUmesh b s
The document discusses host plant resistance in sorghum for foliar diseases. It provides background on sorghum as a drought-tolerant cereal crop and identifies important foliar diseases like anthracnose, leaf blight, and rust. It then defines host plant resistance and describes different types of genetic resistance including vertical, horizontal, monogenic, and polygenic resistance. The document outlines a study conducted at ICRISAT, Hyderabad where a sorghum mini-core collection was evaluated for resistance to foliar diseases, identifying sources of resistance.
Nematode populations dynamics threshold levels and estimation ofFrancis Matu
This document discusses nematode population dynamics, threshold levels, and crop loss estimation. It outlines factors that influence nematode thresholds, such as pathogens, soil type, plant vigor, temperature, and antagonistic microbes. The document also describes nematode population dynamics, noting that some species are K-strategists with low reproduction rates while others are r-strategists that can rapidly increase populations when conditions are favorable. Models for estimating nematode multiplication rates are presented, accounting for variables like the maximum reproduction rate and equilibrium population density. Approaches for assessing yield losses from nematodes, including damage models, are also mentioned.
Effects of Chemical Constituents on Insect Pest Population in West African Ok...IOSR Journals
This study examined the effects of chemical constituents on insect pest populations in different genotypes of West African okra (Abelmoschus caillei). Six genotypes were obtained from a germplasm collection and evaluated in a field experiment. Results showed that three genotypes (NGAE-96-0067, NGAE-96-0123, and CEN 10) attracted fewer insects, had lower leaf and pod damage, and contained higher levels of chemical constituents that conferred resistance to insects. These three genotypes are recommended for farmers despite insect attacks due to their economic value. A positive correlation was found between insect damage and reduced seed yield, indicating that insect resistance is important for okra production. The study concluded that antixen
The document discusses two invasive alien species: Liriomyza trifolii (American serpentine leaf miner) and Ceratitis capitata (Mediterranean fruit fly). L. trifolii originated in North America and has a wide host range of over 29 plant families. It can develop up to 32 generations per year in tropical areas. C. capitata is native to sub-Saharan Africa and has spread globally through the transport of infested fruits. As a highly polyphagous species, its larvae develop in many fruits including citrus, mangoes, and coffee. Standard control methods for both pests include the use of insecticides and sterile insect techniques.
The document defines different types of mycorrhizal associations between fungi and plant roots that provide benefits to both organisms. It describes arbuscular mycorrhizas formed by Glomeromycota fungi in plant roots, which usually have structures called arbuscules and vesicles. It also discusses ectomycorrhizal associations with a Hartig net between root cells and a fungal mantle on root surfaces. The document provides examples of orchid mycorrhizas with fungal coils inside thin root cells, and ericoid mycorrhizas in the plant family Ericaceae with fungal coils or hyphae in root cells.
Here i would like to inform you on the global scenario on whitefly management i hope it will increase your understanding of the management of the whiteflies,,,,,,,,,,,,,,,,,,,,,,,,,,,,
This document summarizes a presentation about learning from past plant epidemics. It discusses two case studies: the Irish Potato Famine of 1845-1850, which was caused by late blight fungus and resulted in over 1 million deaths in Ireland from starvation. The second case study discusses the 1970 Southern Corn Leaf Blight epidemic in the US, where a fungus destroyed 80-100% of corn crops due to the widespread use of susceptible hybrid varieties. The presentation also covers current threats to US agriculture from diseases and pests, strategies for combating epidemics, and emerging technologies.
Eriophyoid Mites as Vector of Plant Pathogenseidmk230
Eriophyoid mites are a diverse group of phytophagous mites that can transmit plant pathogens. Some key plant diseases transmitted by eriophyoid mites include wheat streak mosaic disease transmitted by Aceria tosichella, fig mosaic disease transmitted by Aceria ficus, and rose rosette disease transmitted by Phyllocoptes fructiphilus. Eriophyoid mites acquire and transmit viruses in a circulative, non-persistent manner between plant hosts. They have attributes that make them highly efficient vectors, such as short acquisition periods, ability to transmit between life stages, and high reproduction rates. Further research on eriophyoid mite vector and plant pathogen interactions could
Eriophyoid Mites as Weed Biological Control Agenteidmk230
Eriophyoid mites have potential as biological control agents for invasive weeds. Several species of eriophyoid mites have been successfully introduced and established to control various weed species. Examples discussed include Aceria chondrillae, which forms galls on Chondrilla juncea (skeleton weed) in Australia, reducing its growth and reproduction. Aceria malherbae also forms galls on Convolvulus arvensis (bindweed), limiting its flowering and seed production. Eriophyoid mites have advantages as biological control agents, including high host specificity, ability to reduce plant fitness, and rapid reproduction. However, their effectiveness can be impacted by environmental conditions, host plant resistance,
Invasive Alien Plant Species Assessment in Urban Ecosystem: A Case Study from...Surendra Bam
Invasive Alien Species (IAS) are the second most threat to biodiversity after habitat loss and fragmentation. Identifying the non-native species being naturalized in your region is the fundamental step for the upcoming management strategy in future.
This document discusses trap cropping, which involves planting a secondary crop that attracts pests away from the primary crop. There are several types of trap cropping based on plant characteristics or deployment methods. Trap cropping works by exploiting insects' attraction to plant volatiles and host preferences. While effective against some pests, trap cropping also has limitations such as additional land and production costs. The document provides many examples of specific trap crops used against various insect pests.
The document discusses the Plant Microbiome Project which aims to understand the relationships between plants and their associated microbes. Specifically, it seeks to determine what genetic factors influence whether a microbe benefits or harms a plant. The author's role is to sequence microbes found living in seaweed to study their effects when inoculated in Arabidopsis plants and duckweed. Preliminary results found genera like Bacillus and Geobacillus in bacteria isolated from seaweed in Brazil. Future work includes testing the seaweed microbes' effects on plant growth and sequencing any beneficial microbes.
1. The document discusses mungbean yellow mosaic virus (MYMV) which is a major biotic stress for mungbean crops. MYMV is transmitted by the whitefly vector Bemisia tabaci and causes significant yield losses.
2. Research has found that resistance to MYMV in mungbean is controlled by a single recessive gene. Studies identified RAPD markers linked to the MYMV resistance gene which can enable marker-assisted selection for resistant varieties.
3. Breeding efforts aim to develop MYMV-tolerant mungbean varieties through identification of resistant lines, interspecific crosses, and induced mutations. The ultimate goal is generating superior genotypes with durable resistance to minimize yield losses
This document summarizes a study on the development of resistance to Bt corn by the spotted stem borer (Chilo partellus) in Kenya over four generations. The study found significantly fewer surviving borers from Bt corn events expressing Cry1Ab and Cry1Ba toxins compared to non-Bt corn. There was no significant difference between the two Bt events. Additionally, there was no evidence that the borer population developed resistance to the Cry toxins over the generations studied, indicating Bt corn can effectively control this pest.
The document defines a pest as any organism that interferes with human health, food supply, or quality of the environment. It notes that approximately 1 million insect species have been named, with 500,000 being herbivorous plant-eating insects and 3,500 of those causing problems for humans. Pests are classified based on their population levels relative to economic thresholds and whether they are occasional, key, or potential pests. The document also describes different types of insect damage and symptoms caused by biting/chewing and piercing/sucking insects.
Yellow Mosaic of Legume: Biology, Epidemiology & IDMSaurabh Sarode
The document summarizes a seminar presentation on yellow mosaic diseases of legumes. It discusses mungbean yellow mosaic virus (MYMV) which affects several legume crops including mungbean, blackgram, mothbean, and soybean. MYMV is caused by begomoviruses transmitted by the whitefly Bemisia tabaci. It causes symptoms like yellowing, stunting and loss of yield. Factors like temperature and humidity influence disease spread. Integrated disease management approaches for MYMV include host plant resistance, insecticide application, and weed control. Tables show effects of different management methods on disease incidence and yield.
This document provides an overview of nematodes, including their tiny worm-like structure, prevalence in soils worldwide, and ability to severely impact plant growth. It describes some major genera of plant-parasitic nematodes found in the US, such as root-knot, cyst, and lesion nematodes, and the symptoms and damage they cause, such as root galling, stunting, and wilting. The document also notes nematodes have a wide host range and discusses some of their soil and climate preferences that influence their populations.
Cassava green mite a case study of biological controlJawwad Mirza
This document discusses the classical biological control of the cassava green mite, an invasive pest of cassava in Africa. It describes the mite's origin in South America and introduction to Africa in the 1970s, where it spread to 27 countries by 1985, reducing cassava yields by up to 80%. Efforts by the International Institute of Tropical Agriculture beginning in the 1980s introduced several predatory mite species from South America as biological controls. The most successful was Typhlodromalus aripo introduced to Benin in 1993, which spread to 21 countries, reducing pest mite populations by 90% and increasing cassava yields by 35% within one season, providing an estimated $60 million economic benefit annually.
Mechanism of insect resistance in plants (non preference, antibiosis, tolerance and avoidance) – nature of insect resistance – genetics of insect resistance – horizontal and vertical – genetics of resistance – sources of insect resistance – breeding methods for insect resistance – problems in breeding for insect resistance – achievements.
This document provides an overview of biological control of insect pests that affect oilseed crops in India. It discusses the history of biological control, problems with chemical control, major oilseed crops and their pests. It then outlines different types of biocontrol agents used, including predators, parasitoids, and entomopathogenic fungi, bacteria and viruses. Some examples of specific biocontrol organisms are given. The advantages of biological control are noted as being eco-friendly with no toxicity, while constraints include high costs and slow action. The conclusion states that biological control provides effective, long-term pest population reduction at lower cost than other methods.
This document outlines the post-importation procedures for establishing biological control agents, including quarantine, colonization, establishment, and evaluation. It discusses the four phases that must be completed after natural enemies are shipped to the intended introduction area: quarantine, colonization and establishment, evaluation, and cost/benefit analysis. Quarantine involves preventing the introduction of undesirable species and identifying imported organisms. Establishment requires colonizing an area through direct releases or insectary propagation. Evaluation methods like the addition, exclusion, and interference methods are used to determine the effectiveness of established natural enemies in regulating pest populations.
This document summarizes information about the genus Trichoderma, a type of fungus known for its ability to control plant pathogens and promote plant growth. Some key points:
- Trichoderma species are common soil fungi that can attack and kill other fungi through mycoparasitism, antibiotic production, and competition for resources. They have been widely used as biocontrol agents against phytopathogens.
- Over 100 Trichoderma species have been identified internationally. They are found in soils worldwide and can colonize plant materials and roots. Trichoderma was first described in the late 18th century and its potential as a biocontrol agent was recognized in the early 20th century.
-
This document summarizes information about the genus Trichoderma, a type of fungus known for its ability to control plant pathogens and promote plant growth. Some key points:
- Trichoderma species are common soil fungi that can attack and kill other fungi through mycoparasitism, antibiotic production, and competition for resources. They have been widely used as biocontrol agents against phytopathogens for over 70 years.
- Trichoderma has many advantages as a biocontrol agent, including high reproduction rates, ability to survive harsh conditions, and promotion of plant defenses. However, some species can also be plant pathogens in certain situations.
- Over 100 Trichoderma species have been identified
Sarah 51 Root knot disease of vegetables.pptxSarahAshfaq4
Root knot disease of vegetables is caused by root knot nematodes of the genus Meloidogyne. The nematodes cause galls and knots to form on roots which stunt and damage plant growth. They have a wide host range and infect many economically important crops. The nematodes have a life cycle involving eggs, juveniles and adults. Juveniles penetrate roots and cause galls to form which females feed on. Eggs are then laid outside roots, completing the cycle. Management involves cultural, chemical and biological controls like crop rotation, fumigation and use of antagonistic fungi. Root knot nematodes cause significant losses to vegetable crops in Pakistan, infecting crops like tomato, chili and cotton. Further research is needed to improve
The document discusses two invasive alien species: Liriomyza trifolii (American serpentine leaf miner) and Ceratitis capitata (Mediterranean fruit fly). L. trifolii originated in North America and has a wide host range of over 29 plant families. It can develop up to 32 generations per year in tropical areas. C. capitata is native to sub-Saharan Africa and has spread globally through the transport of infested fruits. As a highly polyphagous species, its larvae develop in many fruits including citrus, mangoes, and coffee. Standard control methods for both pests include the use of insecticides and sterile insect techniques.
The document defines different types of mycorrhizal associations between fungi and plant roots that provide benefits to both organisms. It describes arbuscular mycorrhizas formed by Glomeromycota fungi in plant roots, which usually have structures called arbuscules and vesicles. It also discusses ectomycorrhizal associations with a Hartig net between root cells and a fungal mantle on root surfaces. The document provides examples of orchid mycorrhizas with fungal coils inside thin root cells, and ericoid mycorrhizas in the plant family Ericaceae with fungal coils or hyphae in root cells.
Here i would like to inform you on the global scenario on whitefly management i hope it will increase your understanding of the management of the whiteflies,,,,,,,,,,,,,,,,,,,,,,,,,,,,
This document summarizes a presentation about learning from past plant epidemics. It discusses two case studies: the Irish Potato Famine of 1845-1850, which was caused by late blight fungus and resulted in over 1 million deaths in Ireland from starvation. The second case study discusses the 1970 Southern Corn Leaf Blight epidemic in the US, where a fungus destroyed 80-100% of corn crops due to the widespread use of susceptible hybrid varieties. The presentation also covers current threats to US agriculture from diseases and pests, strategies for combating epidemics, and emerging technologies.
Eriophyoid Mites as Vector of Plant Pathogenseidmk230
Eriophyoid mites are a diverse group of phytophagous mites that can transmit plant pathogens. Some key plant diseases transmitted by eriophyoid mites include wheat streak mosaic disease transmitted by Aceria tosichella, fig mosaic disease transmitted by Aceria ficus, and rose rosette disease transmitted by Phyllocoptes fructiphilus. Eriophyoid mites acquire and transmit viruses in a circulative, non-persistent manner between plant hosts. They have attributes that make them highly efficient vectors, such as short acquisition periods, ability to transmit between life stages, and high reproduction rates. Further research on eriophyoid mite vector and plant pathogen interactions could
Eriophyoid Mites as Weed Biological Control Agenteidmk230
Eriophyoid mites have potential as biological control agents for invasive weeds. Several species of eriophyoid mites have been successfully introduced and established to control various weed species. Examples discussed include Aceria chondrillae, which forms galls on Chondrilla juncea (skeleton weed) in Australia, reducing its growth and reproduction. Aceria malherbae also forms galls on Convolvulus arvensis (bindweed), limiting its flowering and seed production. Eriophyoid mites have advantages as biological control agents, including high host specificity, ability to reduce plant fitness, and rapid reproduction. However, their effectiveness can be impacted by environmental conditions, host plant resistance,
Invasive Alien Plant Species Assessment in Urban Ecosystem: A Case Study from...Surendra Bam
Invasive Alien Species (IAS) are the second most threat to biodiversity after habitat loss and fragmentation. Identifying the non-native species being naturalized in your region is the fundamental step for the upcoming management strategy in future.
This document discusses trap cropping, which involves planting a secondary crop that attracts pests away from the primary crop. There are several types of trap cropping based on plant characteristics or deployment methods. Trap cropping works by exploiting insects' attraction to plant volatiles and host preferences. While effective against some pests, trap cropping also has limitations such as additional land and production costs. The document provides many examples of specific trap crops used against various insect pests.
The document discusses the Plant Microbiome Project which aims to understand the relationships between plants and their associated microbes. Specifically, it seeks to determine what genetic factors influence whether a microbe benefits or harms a plant. The author's role is to sequence microbes found living in seaweed to study their effects when inoculated in Arabidopsis plants and duckweed. Preliminary results found genera like Bacillus and Geobacillus in bacteria isolated from seaweed in Brazil. Future work includes testing the seaweed microbes' effects on plant growth and sequencing any beneficial microbes.
1. The document discusses mungbean yellow mosaic virus (MYMV) which is a major biotic stress for mungbean crops. MYMV is transmitted by the whitefly vector Bemisia tabaci and causes significant yield losses.
2. Research has found that resistance to MYMV in mungbean is controlled by a single recessive gene. Studies identified RAPD markers linked to the MYMV resistance gene which can enable marker-assisted selection for resistant varieties.
3. Breeding efforts aim to develop MYMV-tolerant mungbean varieties through identification of resistant lines, interspecific crosses, and induced mutations. The ultimate goal is generating superior genotypes with durable resistance to minimize yield losses
This document summarizes a study on the development of resistance to Bt corn by the spotted stem borer (Chilo partellus) in Kenya over four generations. The study found significantly fewer surviving borers from Bt corn events expressing Cry1Ab and Cry1Ba toxins compared to non-Bt corn. There was no significant difference between the two Bt events. Additionally, there was no evidence that the borer population developed resistance to the Cry toxins over the generations studied, indicating Bt corn can effectively control this pest.
The document defines a pest as any organism that interferes with human health, food supply, or quality of the environment. It notes that approximately 1 million insect species have been named, with 500,000 being herbivorous plant-eating insects and 3,500 of those causing problems for humans. Pests are classified based on their population levels relative to economic thresholds and whether they are occasional, key, or potential pests. The document also describes different types of insect damage and symptoms caused by biting/chewing and piercing/sucking insects.
Yellow Mosaic of Legume: Biology, Epidemiology & IDMSaurabh Sarode
The document summarizes a seminar presentation on yellow mosaic diseases of legumes. It discusses mungbean yellow mosaic virus (MYMV) which affects several legume crops including mungbean, blackgram, mothbean, and soybean. MYMV is caused by begomoviruses transmitted by the whitefly Bemisia tabaci. It causes symptoms like yellowing, stunting and loss of yield. Factors like temperature and humidity influence disease spread. Integrated disease management approaches for MYMV include host plant resistance, insecticide application, and weed control. Tables show effects of different management methods on disease incidence and yield.
This document provides an overview of nematodes, including their tiny worm-like structure, prevalence in soils worldwide, and ability to severely impact plant growth. It describes some major genera of plant-parasitic nematodes found in the US, such as root-knot, cyst, and lesion nematodes, and the symptoms and damage they cause, such as root galling, stunting, and wilting. The document also notes nematodes have a wide host range and discusses some of their soil and climate preferences that influence their populations.
Cassava green mite a case study of biological controlJawwad Mirza
This document discusses the classical biological control of the cassava green mite, an invasive pest of cassava in Africa. It describes the mite's origin in South America and introduction to Africa in the 1970s, where it spread to 27 countries by 1985, reducing cassava yields by up to 80%. Efforts by the International Institute of Tropical Agriculture beginning in the 1980s introduced several predatory mite species from South America as biological controls. The most successful was Typhlodromalus aripo introduced to Benin in 1993, which spread to 21 countries, reducing pest mite populations by 90% and increasing cassava yields by 35% within one season, providing an estimated $60 million economic benefit annually.
Mechanism of insect resistance in plants (non preference, antibiosis, tolerance and avoidance) – nature of insect resistance – genetics of insect resistance – horizontal and vertical – genetics of resistance – sources of insect resistance – breeding methods for insect resistance – problems in breeding for insect resistance – achievements.
This document provides an overview of biological control of insect pests that affect oilseed crops in India. It discusses the history of biological control, problems with chemical control, major oilseed crops and their pests. It then outlines different types of biocontrol agents used, including predators, parasitoids, and entomopathogenic fungi, bacteria and viruses. Some examples of specific biocontrol organisms are given. The advantages of biological control are noted as being eco-friendly with no toxicity, while constraints include high costs and slow action. The conclusion states that biological control provides effective, long-term pest population reduction at lower cost than other methods.
This document outlines the post-importation procedures for establishing biological control agents, including quarantine, colonization, establishment, and evaluation. It discusses the four phases that must be completed after natural enemies are shipped to the intended introduction area: quarantine, colonization and establishment, evaluation, and cost/benefit analysis. Quarantine involves preventing the introduction of undesirable species and identifying imported organisms. Establishment requires colonizing an area through direct releases or insectary propagation. Evaluation methods like the addition, exclusion, and interference methods are used to determine the effectiveness of established natural enemies in regulating pest populations.
This document summarizes information about the genus Trichoderma, a type of fungus known for its ability to control plant pathogens and promote plant growth. Some key points:
- Trichoderma species are common soil fungi that can attack and kill other fungi through mycoparasitism, antibiotic production, and competition for resources. They have been widely used as biocontrol agents against phytopathogens.
- Over 100 Trichoderma species have been identified internationally. They are found in soils worldwide and can colonize plant materials and roots. Trichoderma was first described in the late 18th century and its potential as a biocontrol agent was recognized in the early 20th century.
-
This document summarizes information about the genus Trichoderma, a type of fungus known for its ability to control plant pathogens and promote plant growth. Some key points:
- Trichoderma species are common soil fungi that can attack and kill other fungi through mycoparasitism, antibiotic production, and competition for resources. They have been widely used as biocontrol agents against phytopathogens for over 70 years.
- Trichoderma has many advantages as a biocontrol agent, including high reproduction rates, ability to survive harsh conditions, and promotion of plant defenses. However, some species can also be plant pathogens in certain situations.
- Over 100 Trichoderma species have been identified
Sarah 51 Root knot disease of vegetables.pptxSarahAshfaq4
Root knot disease of vegetables is caused by root knot nematodes of the genus Meloidogyne. The nematodes cause galls and knots to form on roots which stunt and damage plant growth. They have a wide host range and infect many economically important crops. The nematodes have a life cycle involving eggs, juveniles and adults. Juveniles penetrate roots and cause galls to form which females feed on. Eggs are then laid outside roots, completing the cycle. Management involves cultural, chemical and biological controls like crop rotation, fumigation and use of antagonistic fungi. Root knot nematodes cause significant losses to vegetable crops in Pakistan, infecting crops like tomato, chili and cotton. Further research is needed to improve
Recent Trends in Nematode Management Practices: The Indian ContextIRJET Journal
1) Nematodes pose a serious threat to crop production worldwide, causing over $100 billion in damages annually.
2) The document discusses recent trends in nematode management practices in India, including the use of crop rotations, nematicides, and developing resistant plant varieties.
3) It emphasizes the need for more sustainable and environmentally-friendly approaches like using naturally occurring nematicides, biological control, and integrated pest management systems to control nematodes while reducing environmental impacts.
Pratylenchus vulnus is a plant-pathogenic nematode that infects the roots of many plants, including Persian walnut, grapes, citrus, stone fruits, and berries. It causes lesions on roots that reduce plant vigor and yield. P. vulnus has a wide host range and is established throughout California, where it is a primary cause of tree decline. Management strategies include nematicides, hot water treatment of roots, and using tolerant rootstocks, though options are now more limited since the loss of methyl bromide and DBCP.
Importance of nematodes in horticultural crops and root knot nematodeAdhiyamaan Raj
This document discusses nematodes, specifically root knot nematodes, that affect horticultural crops. It notes that nematodes are tiny worm-like animals invisible to the naked eye. About 50% of nematode species are free-living in soil and help with nutrient cycling, decomposition, and pollution indication. Some, like root knot nematode, are plant parasitic and infect crops like tomatoes, eggplants, chilies, and okra, forming galls on roots and stunting plant growth. Management strategies include using nematode-resistant cultivars, crop rotation, solarization, and nematicides. Entomopathogenic nematodes in the genera Steinernema and Heterorhabditis are beneficial for controlling some
This document provides an overview of nematodes and methods for managing plant-parasitic nematodes in a sustainable way. It begins with an introduction that defines nematodes and describes their prevalence in soil. It then discusses the major plant-parasitic nematode genera and their effects on plants. The rest of the document covers symptoms of nematode damage, sampling techniques, and alternative control methods like preventing spread, managing soil biology, crop rotations, cover crops, botanical nematicides, biocontrols, plant resistance, and other cultural practices.
NEMATOLOGY-DEFINITION, HISTORY AND ECONOMIC IMPORTANCE.pptxnaseeruddinshah2
Nematology is the study of nematodes, which are roundworms that exist worldwide in all environments. Nematodes constitute the largest group of animals and are mostly found in soil. Many nematode species are important parasites of plants and animals, causing significant economic losses. It is estimated that plant parasitic nematodes cause over $78 billion in annual crop losses worldwide through reduced growth, stunting, and yield reductions in major crops like wheat, rice, and potatoes. The root-knot nematode, cyst nematodes, and lesion nematodes are among the most economically important and damaging plant parasitic nematodes globally and in India.
This document discusses potential methods for controlling lethal yellowing disease (LYD) in coconut palms, which is caused by phytoplasma bacteria and spread by insect vectors. It first provides background on LYD and describes current control challenges like the inability to culture phytoplasma. Then it discusses several potential control approaches, including:
1. Using the CRISPR/Cas9 gene editing system or entomopathogenic fungi to control the disease-causing phytoplasma bacteria or their insect vectors.
2. Breeding resistant coconut varieties, though current breeding efforts are outpaced by rising disease incidence.
3. Integrated pest management using traditional vector control plus novel techniques like manipulating symb
Entomopathogenic nematodes and protozoans— mode of action.pptbashirlone123
Protozoans and entomopathogenic nematodes can be used as biological insecticides. Protozoans like Nosema locustae infect and kill grasshoppers, reducing their populations. Two genera of nematodes, Steinernematidae and Heterorhabditdae, infect a wide range of soil-dwelling insects. They carry bacteria that kill the insect, allowing the nematodes to feed and reproduce before finding new hosts. Nematodes must be formulated and applied carefully to ensure they remain viable in soil and infect target pests.
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Controlling the Root-knot Nematodes (RKNs) Hamid Abbasi Moghaddam*and Mohammad Salari**
1. ISSN No. (Print): 0975-1130
ISSN No. (Online): 2249-3239
Controlling the Root-knot Nematodes (RKNs)
Hamid Abbasi Moghaddam*and Mohammad Salari**
*M.Sc. Student, Department of Plant Protection, Faculty of Agriculture, University of Zabol, IRAN
**Associate Professor, Department of Plant Protection, College of Agriculture, University of Zabol, IRAN
(Corresponding author: Hamid Abbasi Moghaddam)
(Received 28 August, 2015, Accepted 29 November, 2015)
(Published by Research Trend, Website: www.researchtrend.net)
ABSTRACT: Root-knot nematodes (RKNs) are ubiquitous parasites with an amazing capacity to interact
with a very large variety of plant species. They are sedentary endoparasitic nematodes that depend on the
induction of a permanent feeding site in living roots to complete their life cycle. RKNs interfere with the
genetic programmes of their hosts to transform root vascular cells into giant cells (GCs) through the injection
of nematode effectors from their oesophageal glands. Dramatic rearrangements in GCs cytoskeleton,
alteration of cell cycle mechanisms, such as mitosis and endoreduplication, readjustment of enzymes involved
in carbohydrate synthesis and degradation are among those processes modified in GCs. GCs act as sinks to
provide nutrients for life cycle completion from J2 larvae to adult females. The female produces an egg
offspring protected by a gelatinous matrix and the free-living stage, J2, hatch from these eggs, completing the
nematode life cycle. The understanding of the processes subjacent to GC differentiation and maintenance, as
well as a deeper knowledge of RKN mode of parasitism, will provide tools for new control methods of these
devastating agricultural pests.
Key words: Root-knot nematodes, GCs, parasites,
INTRODUCTION
Root-knot nematodes, Meloidogyne spp., (RKNs) are a
serious threat to agriculture in tropical and subtropical
and temperate regions wherever agriculture is practiced
(Moens et al., 2009). The most damaging species of
root-knot nematode, Meloidogyne incognita has been
found associated with tomato crops in developing
countries including Pakistan (Khan et al., 2000).
Nematicides such as methyl bromide are widely used to
control nematodes but many have been phased out of
use and withdrawn from the international market
because of human health and environmental concerns
(Moens et al., 2009). Biological control agents (BCAs)
such as Trichoderma harzianum Rifai (Sharon et al.,
2001; Khattak, 2008) have shown some promise for use
against RKNs on tomato, but this BCA is not
commercially available to many growers in countries
such as Pakistan (Khattak, 2008). They also show
varied lifestyles (with representatives from free-living
to parasitic species) and food resources (plants,
bacteria, animals and fungi) (Perry & Moens, 2011).
There are nematodes detrimental to agriculture,
parasites of animal and humans, but also beneficial
species, such as the entomopathogenic nematodes used
in crop protection as insect control agents (Lacey &
Georgis, 2012; Ravichandra, 2008), as well as free-
living nematodes involved in soil nutrient turnover. So
far, more than 25.000 spp. have been included in the
phylum (Zhang, 2013) but this number is constantly
increasing as new species are discovered or redescribed
(Elling, 2013). Classic taxonomy proposed two classes,
based on morphological and anatomical characters
(Chromadorea and Adenophorea),which diverged over
550 million years ago. Recently, a more comprehensive
phylogenetic classification based mainly on molecular
analysis of small subunit of ribosomal DNA
(ssUrDNA) was proposed: Chromadorea and Enoplea
(De Ley & Blaxter, 2002; De Ley & Blaxter, 2004;
VanMegen et al., 2009). As an indirect consequence of
infection, aboveground plant parts are altered, showing
a reduced growth, leaf chlorosis, poor yield and wilting.
Crop losses, are sometimes underestimated because
plant symptoms after the infection are unspecific and
can be erroneously identified as resulting from
nutritional deficiencies or abiotic stress. Most plant
parasitic nematodes suffer four moults throughout their
development from the juvenile stage (stages 1e4, J1eJ4)
until reaching the adult stage. Transition from J1 to J2
usually takes place within the egg, and after this first
moult the egg hatches releasing the J2, which represents
for the majority of the species the infective stage (Perry
& Moens, 2011). J2 larvae are mostly microscopic
(from 250 mm to 12 mm in length) and live in soils
without feeding until they find a suitable host. Then, J2
invade and feed on living plants through a protrusible
oral stylet that they use to puncture cells and to feed
from them. Throughout their developmental stages,
nematodes usually maintain a vermiform, worm-like
shape. However, in several nematode species, such as
Meloidogyne spp., Heterodera spp., Rotylenchus spp.
and Tylenchulus spp., adult females adopt a swollen,
pear-like or kidney-like shape (Decraemer & Hunt,
2013). Plant parasitic nematodes are classified
according to their lifestyle and feeding habits.
Biological Forum – An International Journal 7(2): 914-922(2015)
2. Moghaddam and Salari 915
Those that penetrate the host root to feed from different
inner cell types are classified as endoparasites, whereas
the nematodes that feed externally by inserting their
mouth stylets into root cells from the root surface are
called ectoparasites. They are further sub classified into
sedentary, when they have a sessile stage, or migratory
(Decraemer & Hunt, 2013). Examples of genera
included in all these categories are found among the
major agriculturally relevant nematode species. For
instance, the sedentary ectoparasite Tylenchulus
semipenetrans (citrus nematode) is responsible for
losses in citrus and olive trees and, to a lesser extent,
grapevines. The lance and the needle nematodes
(Hoplolaimus spp. and Longidorus spp. respectively)
are migratory ectoparasites that cause considerable
losses in turf grasses and lawns, corn crops and grape
vineyards. Migratory ectoparasitic nematodes are
particularly relevant, as some act as virus vectors (e.g.
Xiphinema spp., a grapevine pathogen). Among the
endoparasitic nematodes, there are migratory species
(e.g. Pratylenchus spp., a major problem in fruit trees)
and sedentary ones, which constitute a most relevant
group in agriculture. Sedentary endoparasitic
nematodes show the most sophisticated parasitism
behaviour; they develop an intimate relationship within
their hosts, inducing highly specialized 'pseudo-organs'
to provide them with a continuous source of food. This
group is represented by the root-knot nematode (RKN;
Meloidogyne spp.) and the cyst nematodes (e.g.
Heterodera and Globodera spp.), receiving their names
from the characteristic structures formed in the roots
after their infection: the galls or knots and the syncytia.
Recently, phylogeny methods based on ssUrDNA (van
Megen et al., 2009) support the idea that the similar
parasitism behaviour of root-knot and cyst nematodes
has been acquired by convergent evolution between
both groups rather than the existence of a common
ancestor (Castagnone-Sereno, Danchin, Perfus-
Barbeoch, & Abad, 2013; Castagnone-Sereno, Skantar,
& Robertson, 2011; Perry & Moens, 2011).
Plant damage caused by plant parasitic nematodes is
mostly due to the reduced availability of water and
nutrients because of nematode feeding and disturbance
of root anatomy. Nematode-produced wounding also
predispose the plant to other soil pathogens attack, what
is sometimes favoured by pathogenic bacteria or fungi
carried by the nematode itself (Back, Jones & Goto,
2011). For example, wilt fungus Fusarium oxysporum
can interact with RKNs in complex diseases, affecting
tomato, cabbage or watermelon (Bergeson, Van Gundy,
& Thomason, 1970;) and Ralstonia solanacearum
bacteria can increase tomato wilt when RKNs are
present (Valdez, 1978). For cyst nematodes, complex
diseases are found mainly in potato and soybean crops
(Back et al., 2002).
GENERAL ASPECTS OF ROOT-KNOT
NEMATODES (RKNs)
Meloidogyne is a genus formed by more than 90 species
(Jones et al., 2013), some of them including several
races (Eisenback & Triantaphyllou, 1991; Ravichandra,
2008). Only a few species are referred as major
agricultural pests, as they were considered the most
abundant and damaging: Meloidogyne incognita,
Meloidogyne javanica, Meloidogyne arenaria from
Mediterranean and tropical areas, and the temperate
species Meloidogyne hapla. Additionally, species
previously considered minor agricultural pests as
Meloidogyne enterolobii, Meloidogyne paranaensis or
Meloidogyne exigua (from tropical and subtropical
regions), and Meloidogyne fallax, Meloidogyne minor
or Meloidogyne chitwoodi (from temperate regions) are
emergent parasites that receiveincreasing attention
(Elling, 2013; Moens, Perry, & Starr, 2009) as they are
raising as important agriculture threats. Some of them,
such as M. chitwoodi, M. enterolobii or M. fallax, have
been included in the 2013 quarantine pest list from the
European and Mediterranean Plant Protection
Organization. As previously indicated, RKNs are
extremely polyphagous parasites. Meloidogyne spp.
such as M. incognita, M. javanica, M. hapla, M.
arenaria, M. enterolobii, M. fallax or M. chitwoodi
show a broad host range, being able to parasitize
vegetable crops, fruit trees and ornamental plants,
whereas other species show a more restricted host
range, as M. minor (grasses, potato and tomato) or
Meloidogyne hispanica (peach, sugar beet, tomato). In
accordance to this, species with narrower host ranges
show more restricted geographical localizations, but as
their host range widens, they show a global distribution
(Triantaphyllou, 1985).
Control strategies in agriculture cover the use of
chemicals (nematicides and fumigants), biological
control with nematode antagonists, physical methods,
such as solarization and fallowing, cultural methods as
crop rotation, as well as the use of resistant plants. The
use of chemicals is gradually vanishing due to their
toxicity and environmental contamination potential.
The frequently used methyl bromide, a broad spectrum
and economically viable pesticide, has been banned in
the European Union since 2010 (Kearn, Ludlow,
Dillon, O'Connor, & Holden-Dye, 2014) and other
countries are reducing its use. Organophosphate- and
carbamate-based nematicides are also restricted. Those
belonging to the fluoroalkenyl thioether group are
effective against RKN showing a lower impact on the
environment as compared to organophosphate- and
carbamate-based nematicides and new nematicides
derived from biologically active compounds such as
those found in garlic are being developed (Kearn et al.,
2014).
3. Moghaddam and Salari 916
However, effective chemical pesticides against these
complex eukaryotes will mostly be potentially harmful
for other organisms. Biological control has resulted in
a low effective strategy unless applied in combination
with other techniques (Viaene, Coyne, & Kerry, 2006).
The use of nematode antagonists that can be predators,
parasites or pathogens such as the fungi Verticillium
spp. and Fusarium spp., or the bacteria Pasteuria
penetrans, is at its initial days. Despite being an
ecofriendly strategy, few commercial products
containing viable organism for biological control are
available (Stanton & Stirling, 1997; Timper, 2011).
Crop rotation with non host species or resistant
cultivars has provided good results for RKN control.
Despite few poor or non host plant species are
available, cover crops as marigolds (Tagetes spp.) or
perennial grasses (such as bahiagrass (Paspalum
notatum) and bermudagrass (Cynodon dactylon L.
Pers.)) have been effective to control populations of M.
arenaria, M. hapla, M. incognita and M. javanica
(Hooks, Wang, Ploeg, & McSorley, 2010; Netcher &
Taylor, 1979). With regard to resistant cultivars, several
genes from tomato (Mi genes; Ammiraju, Veremis,
Huang, Roberts, & Kaloshian, 2003; Rossi et al., 1998;
Veremis, van. Heusden, & Roberts,1999; Yaghoobi,
Kaloshian, Wen, & Williamson, 1995), prunus (Ma and
RMia genes; Claverie et al., 2004; Lu, Sossey-Alaoui,
Reighard, Baird, & Abbott, 1999), carrot (Mj genes; Ali
et al., 2014) and pepper (Me genes; Djian-Caporalino et
al., 2007) have been described to confer resistance to
many Meloidogyne spp. However so far only the
tomato Mi-1 gene has been cloned and successfully
transferred to commercial cultivars (Devran & S€og€ut,
2010). Mi-1 confers resistance to three Meloidogyne
spp. (M. javanica, M. incognita and M. arenaria), but
this resistance is easily overcome when soil temperature
increases (reviewed by Williamson (1998)). In addition,
the isolation of virulent Meloidogyne spp. populations
in tomato cultivars carrying the Mi-1 gene questioned
the durability of the Mi-resistance (Jacquet et al., 2005)
and prompted the suggestion of a relationship between
resistance breakdown and Mi gene dosage (Jacquet et
al., 2005). Moreover, the durability of the Me gene
seems to be influenced not only by allelic dosage but
also by the genetic background, since other genes or
quantitative trait loci may be contributing to resistance
(Djian- Caporalino et al., 2014).
All these strategies should be combined in an integrated
pest management (IPM) plan for effective control of
RKN population in the field. A detailed evaluation of
the cropping systems and accurate diagnosis of RKN
species must be performed for an IPM successful
implementation. Differences regarding host preferences
that exhibit races of a determined species (e.g. for M.
incognita all 4 races described can infect tomato cv.
Rutgers, whereas only races 3 and 4 can parasite cotton
cv. Deltapine (Hartman & Sasser, 1985; Mahdy, 2002))
should be considered. Therefore, designing an IPM is
very laborious and overall it needs to be locally
designed.
Consequently, there is still a clear need to deeply
understand the molecular basis of the RKNe plant
interaction, including the development and maintenance
of the specific feeding structures induced in the plant
host, galls and giant cells (GCs).
THE MORPHOLOGY AND REPRODUCTION OF
RKNs
RKNs display a conserved basic body plan throughout
their life stages, with morphological features used for
species identification. Briefly, J2 outermost body
structure consists of a body wall encompassing three
layers: the cuticle, the hypodermis (also known as
epidermis) and the somatic muscles. The cuticle is a
flexible, semipermeable exoskeleton with a noncellular,
multilayer structure that is newly synthesized and
secreted by the epidermis in each moult. Cuticle layers
(cortical, medial and basal layer) can vary in thickness
throughout the nematode life stages or can even be
absent as is the case of the medial layer in adult females
(Decraemer & Hunt, 2013; Eisenback, 1985). The
cuticle is a collagenous matrix covered by an outer coat
(epicuticle) mainly made of glycoproteins and other
surface-associated proteins. This coat is probably
involved in host immunity response (Decraemer &
Hunt, 2013; Eisenback, 1985). The cuticle allows solute
diffusion and water and gas exchange with the medium
to compensate the lack of either respiratory or
circulatory system. In females, cuticular morphological
features of the perineum (the region surrounding the
vulva and anus) are used for the perineal pattern
analysis, i.e. a characteristic pattern of ridges and
annulations stablish differences among RKN species.
Beyond the musculature, digestive, reproductive and
nervous systems are found within the RKN body. The
digestive system consists of a mouth with a retractile
stylet connected to an oesophagus (or pharynx) which
ends in an intestine and a rectum. Within the
oesophagus there is a median bulb or metacorpus
containing a metacorporal valve responsible for the
suction force necessary for nutrient uptake and for
pumping out gland secretions coming from the dorsal
and subventral glands. These glands play a main role
during parasitism, including invasion, establishment
and feeding site development. During the preparasitic
stage, the predominant glands are the two subventral
glands, involved in releasing cell wall-degrading
enzymes such as cellulases or pectinases (Davis,
Hussey, & Baum, 2004; Jaubert, Laffaire, Abad, &
Rosso, 2002). However, during the parasitic stage, once
the nematode establishes, the dorsal gland become more
active. Morphological changes of these glands reflect
their predominance during each stage, and thus the
subventral glands reach their maximum size before
invasion and begin to shrink as a nematode settles. On
the contrary, the dorsal gland maximum size is
described for the adult female stage (Hussey & Mims,
1990).
4. Moghaddam and Salari 917
The oesophageal gland secretions (dorsal and
subventral) are released in spherical granules that vary
in size, composition and morphology not only
depending on nematode developmental stage, but also
depending on nematode species (Hussey & Davis,
2004).
HOLISTIC APPROACHES TO TACKLE GCs
SPECIFIC GENE EXPRESSION
During gall and GC ontogeny a profound
reprogrammation of gene expression takes place, as
encountered in transcriptomic analysis such as
microarray (Barcala et al., 2010; Jammes et al., 2005;
Portillo et al., 2009) and massive sequencing (Ji et al.,
2013; Cabrera et al., unpublished). Precise single cell
isolation techniques as microaspiration or laser capture
microdissection combined to global transcriptomic
analysis constituted a step forward to the understanding
of the specific transcriptomic signatures of GCs
(Barcala et al., 2010; Fosu-Nyarko, Jones, & Wang,
2009; Portillo et al.,2013; Ramsay, Wang, & Jones,
2004; Wang, Potter, & Jones, 2003; Ji et al., 2013). It
allowed bypassing the complexity of the gall
transcriptome that included all the different tissues
present in this pseudo-organ, and to stablish differences
between whole gall and GC-specific transcriptomes.
Recently, RNA-sequencing approaches for miRNA
differential expression analysis increased the
complexity of this scenario (Hewezi, Howe, Maier, &
Baum, 2008; Kyndt et al., 2012; Cabrera et al.
unpublished), as miRNAs have come up as key signal
molecules, controlling and regulating many cellular
processes at transcriptional, post-transcriptional and
translational level (Yang, Xue, & An, 2007).
GIANT CELLS (GCs): FROM VASCULAR
CELLS TO NOURISHING CELLS
RKNs were described as plant pathogens from late
1880s (reviewed in Berg et al. (2008)). Initial research
described their morphology and it is not until mid-
1900s when the first studies focused on the nematode-
induced plant morphological changes (Christie, 1936;
Ravichandra, 2008). More detailed morphological
features of the feeding cells induced in the plant hosts
were already described in the 1960s by light and
electron microscopy analysis (Bird, 1961; Huang &
Maggenti, 1969). Nowadays, it still results a challenge
to elucidate those cell processes involved in the
dramatic morphological and physiological changes
induced in the initial root cells transformed into a
specialized structure for the nematode feeding, the GCs.
During this process, the first evidence of a developing
GC inside the root vascular cylinder is the appearance
of binucleate cells near the nematode head (de Almeida
Engler & Favery, 2011).
CONCLUSIONS
RKNs depend on a specifically developed cell type
from their initial root vascular cells to complete its life
cycle. Those GCs are induced and probably maintained
by nematode secretions delivered through their stylets.
Many questions regarding GC ontogeny and
functioning remain unanswered. To date, only a few
players of the complex regulatory networks taking
place during GCs development have emerged, and the
understanding of how these organisms can interact with
their hosts in such a subtle manner is fragmentary. Yet,
integrative analysis of proteomics and transcriptomics
together with genetics and molecular and cell biology
tools are facilitating its comprehension. However, the
complexity of an evolving interaction makes its
analysis a challenge, i.e. feeding site cell status is
continuously changing as it differentiates, controlled by
nematode nutritional needs. Therefore, comparisons
and inferred conclusions from the analysis of galls/GCs
at selected infection points should be taken cautiously.
Furthermore, valuable data were also obtained from the
study of nematode putative effectors and their
molecular interactions to their host targets, as well as
the downstream responses, pointing out common and
specific regulatory pathways manipulated by RKN
and/or cyst nematodes.
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