This document provides an overview of defense mechanisms in plants and patterns of pollination. It discusses structural, chemical, and protein-based defenses plants use against pathogens like fungi, bacteria, and viruses. It also outlines different pollination types including abiotic (wind, water), biotic (insects, birds, bats), and artificial pollination used in hybridization. The document contains detailed information on specific defense structures, chemicals, and the characteristics of different pollination methods. It aims to explain the complex interactions between plants and pathogens or pollinators.
About 20,000 species.
Eukaryotic cell and contain all the membrane bound organelles.
Thallus is green due to the presence of green pigment chlorophyll.
Chlorophyll is contained in chloroplast.
Pyrenoids embedded in chloroplast.
Cytoplasm contains vacuoles.
Motile cell of primitive forms contains eye spot or stigma.
Reserve carbohydrates are in the form of starch.
Cell wall invariably contains cellulose.
Produce motile reproductive bodies generally with two or four flagella.
Most are aquatic but some are subarial.
Several species of ulvales and siphonales are marine.
Some strains of chlorella are thermophilic.
Species of chlamydomonas and some chlorococcales occur in snow.
Coloechaete nitellarum is endophytic.
Cephaleuros is parasitic – cause ‘red rust of tea’.
Live epizoically on or endozoically within the bodies of lower animals – chlorella is found in hydra; chlorella beneath the scales of fish; characium on the antennae of mosquito.
Green algae in assosciation with the fungi constitute lichens.
About 20,000 species.
Eukaryotic cell and contain all the membrane bound organelles.
Thallus is green due to the presence of green pigment chlorophyll.
Chlorophyll is contained in chloroplast.
Pyrenoids embedded in chloroplast.
Cytoplasm contains vacuoles.
Motile cell of primitive forms contains eye spot or stigma.
Reserve carbohydrates are in the form of starch.
Cell wall invariably contains cellulose.
Produce motile reproductive bodies generally with two or four flagella.
Most are aquatic but some are subarial.
Several species of ulvales and siphonales are marine.
Some strains of chlorella are thermophilic.
Species of chlamydomonas and some chlorococcales occur in snow.
Coloechaete nitellarum is endophytic.
Cephaleuros is parasitic – cause ‘red rust of tea’.
Live epizoically on or endozoically within the bodies of lower animals – chlorella is found in hydra; chlorella beneath the scales of fish; characium on the antennae of mosquito.
Green algae in assosciation with the fungi constitute lichens.
Equisetum popularly known a the ‘horse-tail’ or ‘scouring rush’.
It is now represented by nearly 30 species which are seen world wide except in Australia and New Zealand.
Some species prefer damp and shady places while others grow in marshes, ponds or stream banks
Some are found in xerophytic habitats
Equisetum popularly known a the ‘horse-tail’ or ‘scouring rush’.
It is now represented by nearly 30 species which are seen world wide except in Australia and New Zealand.
Some species prefer damp and shady places while others grow in marshes, ponds or stream banks
Some are found in xerophytic habitats
Detailed description on the mode of actions of various phytoalexins, mechanisms involved phtyoalexin formation, various types of phytoalexins, its functions
a detailed description of structural and biochemical mechanisms and importance of phytoalexins in plants and different types of phytoalexins produced the plants and its functions and importance in plant defense mechanism
HELLO Guyzz....Here I upload ppt on DEFENCE MECHANISM IN PLANTS.The content is brief accurate and so you can understand easily,Have a look and plz give your valuable comments.
In plants some structures are already present to defend the attack while in others, the structures to defend the host develops after the infection. In this way, structural defense can be characterized as
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
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spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
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Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
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Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
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Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
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Defense Mechanism & Pollination pattern in plants ppt
1. A PRESENTATION ON
“ DEFENSE MECHANISM” & "POLLINATION
PATTERN” IN PLANTS
Presented By :
Sunil Kumar Sahoo
Enrolment No-CUSB1703132020
SECOND Semester,
Msc Life science (L.Sc.-552)
2. DEFENSE MECHANISM IN PLANTS
INTRODUCTION –
- Plants represent a rich source of nutrients for many organisms including fungi,
bacteria, virus, nematodes, insects, and vertebrates.
- Plant lacking an immune system comparable to animals.
- Plants have developed a stunning array of structural, chemical, and protein based
defenses designed to detect invading organisms and stop them before they are
able to cause extensive damage.
- Each plant species is affected by approximately 100 different kinds of fungi,
bacteria, mollicutes, viruses and nematodes.
4. I) STRUCTURAL DEFENSE MECHANISM
-The surface of the plant or host is first line of defense against the pathogen.
-The pathogen must adhere to the surface and penetrate, if it is to cause
infection.
Structural defense mechanism are mainly two type:-
1. Pre-existing structural defense mechanism
2. Post-infectional or induced structural defense mechanism
Pre-existing structural defense
1.Wax
2.Thick cuticle
3.Thickness and toughness of the outer wall of epidermal cells
4.Stomata
5.Sclerenchyma cells
6.Lenticel
5. i)Induced structural defense –
1. Cellular defense structure
-Hyphal sheathing
2. Histological defense structure
- Formation of cork layer
-Formation of abscission layer
- Formation of tyloses
-Deposition of gums
A) PRE-EXISTING STRUCTURAL DEFENSE –
It includes:
- Amount and quality of wax and cuticle.
-Shapes, size and locations of natural openings (stomata and lenticels).
- Presence of thick walled cells in the tissues of the plant that hinder the advance
of pathogen.
6. Wax-
It is the mixture of long chain of apolar lipid.
-It forming a protective coating on plant leaves
and fruit.
-Synthesized by epidermis.
- Extremely hydrophobic.
Cuticle & Epidermal cell –
-Ex: Disease resistance in Barberry species infected with Puccinia graminis tritici has been
attributed to the tough outer epidermal cells with a thick cuticle.
-In linseed, cuticle acts as a barrier against Melampsora lini.
-Silicification and lignifications of epidermal cells offers protection against Pyricularia
oryzae and Streptomyces scabies in paddy and potato, respectively.
7. B)POST-INFECTIONAL/INDUCED STRUCTURAL DEFENSE MECHANISM-
-Most pathogen manage to penetrate their hosts through wounds and natural opening and to
produce various degree of infection.
- Pathogen penetration through the host surface induced the structural defense mechanism in
the host cells.
These may be regarded as:-
-Histological defense barriers (cork layer, abscission layers and tyloses formation)
-Cellular defense structures (hyphal sheathing).
HISTOLOGICAL DEFENSE STRUCTURES-
Cork layer :-
- Infection by fungi, bacteria, some viruses and nematodes induce plants to form several layers of
cork cells beyond the point of infection.
- These cork cells inhibits the further invasion by the pathogen beyond the initial lesion and also
blocks the spread of toxin substances secreted by the pathogen.
Abscission layers:-
-An abscission layer consists of a gap formed between infected and healthy cells of leaf
surrounding the locus of infection.
- Due to the disintegration of middle lamella of parenchymatous tissue.
- Gradually, infected area shrivels, dies, and sloughs off, carrying with it the pathogen
-Abscission layers are formed on young active leaves of stone fruits infected by fungi, bacteria or
viruse
8. TYLOSES-
- Tyloses are the overgrowths of the protoplast of adjacent living parenchymatous cells,
which protrude into xylem vessels through pits.
-Tyloses have cellulosic walls.
-It formed quickly ahead of the pathogen and may clog the xylem vessels completely
blocking the further advance of the pathogen in resistant varieties.
Ex: Tyloses form in xylem vessels of most plants under invasion by most of the vascular wilt
pathogens.
GUM DEPOSITION-
-Various types of gums are produced by many plants around lesions after infection by
pathogen or injury.
-Generally these gums are exudated by plant under stressed condition.
9. II)BIOCHEMICAL DEFENSE MECHANISM-
Pre-existing chemical defense –
1. Inhibitors-
-Released by plant in it’s environment.
-Present in plant cells before infection.
2.Phenolics-
-Tannins
- Glucanases
-Dienes
-Chitinase
Induced chemical defense –
Hypersensitivity response (HR)
Production of Antimicrobial substances
-Phytoalexins
-Plantibodies
10. INHIBITORS RELEASED BY THE PLANT IN IT’S ENVIRONMENT –
-Plants exude a variety of substances through the surface of their aboveground parts as well
as through the surface of their roots.
-Inhibitory substances directly affect micro-organisms or encourage certain groups to
dominate the environment which may act as antagonists to pathogens.
Ex 1: Root exudates of marigold contain α-terthinyl which is inhibitory to nematodes.
Ex 2: In Cicer arietinum (chickpea), the Ascochyta blight resistant varieties have more
glandular hairs which have maleic acid which inhibit spore germination.
Ex 3:Red scales of red onion contain the phenolic compounds, protocatechuic acid and
catechol.
11. INHIBITORS PRESENT IN PLANT CELLS BEFORE INFECTION-
-It is becoming increasingly apparent that some plants are resistant to disease caused by
certain pathogens of an inhibitory compound present in the cell before infection.
-It stored in vacuoles of plant cells.
Phenolics – onion (catechol and protocatechuic acid ).
Tannins, and some fatty acid-like compound such as dienes,which are present in high
concentrations in cells of young fruits, leaves or seeds. These compounds are potent
inhibitors of many hydrolytic enzymes.
Ex: Chlorogenic acid in potato inhibits common scab bacteria, Streptomyces scabies,and to
wilt pathogen, Verticillium alboatrum
Saponins:-
- It have antifungal membranolytic activity. Ex: Tomatine in tomato and Avenacin in oats.
Lactins:-
- They are protiens. Bind specifically to certain sugars and occur in large concentrations in
many types of seeds, cause “lysis” and growth inhibition of many fungi.
Hydrolytic enzymes:-
-“Glucanases” and “chitinases” enzymes.
-It may cause breakdown of pathogen cellwall.
12. INDUCED CHEMICAL DEFENSE –
Phytoalexins:- (Phyton = plant; alexin = to ward off)
-Muller and Borger (1940) first used the term phytoalexins for fungistatic
compounds produced by plants in response to injury (mechanical or
chemical) or infection.
- Phytoalexens are toxic antimicrobial substances.
- It produced in appreciable amounts in plants only after stimulation by
phytopathogenic micro-organisms or by chemical or mechanical injury.
-Phytoalexins are not produced during compatable reaction.
Characteristics of phytoalexins:-
- Fungitoxic and bacteriostatic at low concentrations.
-Produced in host plants in response to stimulus (elicitors) and metabolic
products.
-Absent in healthy plants.
- Remain close to the site of infection.
-Produced in quantities proportionate to the size of inoculum.
- Produced in response to the weak or
13. CONCLUSION –
-Both the host and pathogen evolve in nature side by side.
-Disease development depends upon successful host-pathogen interaction.
- Susceptibility and resistance of a host against various pathogens is
predominantly decided by the gene.
-Different types of chemical and structural defense mechanism provide plant
defenses response to the pathogens.
-Defense mechanism will not work ,when compatible reaction occurs between
host and pathogen.
14. POLLINATION PATTERN IN PLANTS
• The transfer of pollen grains from an anther to the stigma in
angiosperms or from the microsporangium to the micropyle in
gymnosperms is called as pollination.
• Two types of pollination are generally found like
1. Self-pollination
2. Cross-pollination
15. ABIOTIC AGENCIES-
i)ANEMOPHILY-
- It is a mode of cross pollination or transfer of pollen grains through the agency
of wind.
-Example: Coconut Palm, Date Palm, Maize, many grasses, Cannabis.
Characterstics :
-The flowers are colourless, odourless & nectarless.
- Pollen grains are light, small and winged or dusty,
dry smooth, nonsticky and unwettable.
- Stigma is hairy, feathery or branched to catch the
wind-borne pollen grains.
- Pollen grains are produced in very large number.
16. ii)HYDROPHILY-
- It is the mode of pollination or transfer of pollen grains through the agency of
water.
- Example - Zoostera , Vallisneria, Ceratophyllum,
Hydrilla ,Lemna.
Characters:
-Flowers are small and inconspicuous.
- Nectar and odour are absent.
-Pollen grains are light and unwettable
due to presence of mucliage cover.
- Stigma is long, sticky but unwettable.
17. BIOTIC AGENCIES-
i)ENTOMOPHILY-
• -The pollen grains are transferred to a mature through the agency of insects like
moths, butterflies, wasps, bees, beetles, etc.
• -Examples of insect pollinated flowers are Jasmine,Bougainvillea ,Sunflower
,Cestrum ,Amorphophallus.
Characters :
- They are showy or brightly coloured.
- Most insect pollinated flowers have a
landing platform.
-The pollen grains are spiny, heavy and
surrounded by a yellow oily sticky substance
called pollenkit.
- Stigmas are often inserted and sticky.
-Some flowers provide safe place to insects for
laying eggs, e.g., Yucca.
18. • Some flowers that mimic female bees or wasps.
• Look like females.
• Smell like females: chemical mimicry. One study
showed flower more attractive than real female.
• Example – Sexual mimic orchids
ii) ORNITHOPHILY-
-It is the mode of allogamy performed by birds. Only a few types of birds are specialised for this.
They usually have small size and long beaks.
Example : Salmalia &Erythrina (by Crows & Mynas)
Characters :
- Ornithophilous flowers are usually brightly coloured— red, orange, yellow or blue.
- The floral parts are commonly leathery.
19. iii) CHIROPTEROPHILY –
-Pollination carried out by bats is descried as chiropterophily.
-The common examples of chiropterophilous flowers are durio, kigella pinnata,
anthocephalus (kadamb), adansonia (baobab tree), bauhinia etc.
Characters :
1.The flowers are freely exposed, large and tough so that bats can hold on to them.
2. The flowers open in the evening since bats are nocturnal animal.
3. The flowers give off a strong scent like that of rotting fruits to attract bats.
4. Bats feed on nectar and pollen produced in very large amounts by these flowers.
20. POLLINATION AS MUTUALISM –
- Most flowering plants are pollinated by animals.This usually viewed as mutualism (where
both species benefit).
- Plant gets pollen transferred & Animal gets “reward”.
- The rewards may be
1. Pollen (high in protein, Also has lipids, minerals, starch)
2. Nectar (sugary fluid produced by nectar glands (nectaries) in flower)
3. Oils/Resins: some used as construction materials, “cologne” (male solitary bee uses oil
as female attractant), food for larvae (Krameria)
4. Edible petals e.g.(pineapple guava: New Zealand)
Krameria wax gland: wasp food
21. ARTIFICIAL POLLINATION -
- This technique is used for the purpose of Hybridization.
- It involves pollination of desired female parents with pollen from the desired
male parent, taking all precautions to prevent contamination of stigma with
undesired pollen.
- In unisexual plants the procedure is simple but its complicated in bisexual ones.
- 2 processes that takes place in bisexual flower : Emasculation & Bagging
22. CONCLUSION –
-Pollination is a vital process of nature that isn’t very well known, but
is extremely important in the food growing processes, and without
it, we would be in trouble.
- For the fruit seeds to develop, pollen has to be transferred
between two flowers of the same species, which then fertilizes the
flower and allows the production of healthy seeds on the plant.