Plant phenolics are secondary metabolites that encompass several classes structurally diverse of natural products biogenetically arising from the shikimate-phenylpropanoids-flavonoids pathways. Plants need phenolic compounds for pigmentation, growth, reproduction, resistance to pathogens and for many other functions. Therefore, they represent adaptive characters that have been subjected to natural selection during evolution. Plants synthesize a greater array of secondary compounds than animals because they cannot rely on physical mobility to escape their predators and have therefore evolved a chemical defence against such predators. This article, after a short review of plant phenols and polyphenols as UV sunscreens, signal compounds, pigments, internal physiological regulators or chemical messengers, examines some findings in chemical ecology concerning the role of phenolics in the resistance mechanisms of plants against fungal pathogens and phytophagous insects.
Metabolites, Secondary metabolites are derived from primary metabolites, Why secondary metabolites, Phenolics, Terpenoids, Alkaloids, Special nitrogen metabolites, Cuticular compounds .The major classes of these found in plants
secondary metabolites of plant by K. K. SAHU SirKAUSHAL SAHU
METABOLITES : Introduction . . .
The chemical compounds produced by plants are collectively called as phytochemicals.
Primary metabolites – participating in nutrition and metabolic processes inside the plant.
Secondary metabolites – those chemical compounds that do not participate in metabolism of plants but influencing the
ecological interactions between the plant and its environment.
The presentation gives overview of production of secondary metabolites using callus culture as well as tissue culture techniques. Various batch and continuous culturing process are described on the basis of secondary metabolite to be synthesised.
Phenyl propanoid pathway by kk sahu sirKAUSHAL SAHU
SYNOPSIS
INTRODUCTION
HISTORY
DEFINITION
PRIMARY VS SECONDARY PLANT METABOLISM
SECONDARY METABOLITES
PHENOLIC COMPOUND
PHENYLPROPANOID PATHWAY METABOLITES
PHENYLPROPANOID BIOSYNTHESIS
BIOCHEMICAL PATHWAYS TO PHENOLIC CLASSES
SOME IMPORTANT PRODUCTS OF PHENYLPROPANOID PATHWAY
LIGNANS AND LIGNINS
FLAVONOIDS
METABOLIC ENGINEERING OF PHENYLPROPANOID PRODUCTION
BIOTECHNOLOGICAL APPLICATIONS
CONCLUSION
REFERENCES
plant pathogen interaction
different types of pathogens
gene for gene hypothesis
direct receptor model
Elicitor receptor model
suppersor repressor model
gaurd hypothesis
Somaclonal Variation in Plant tissue culture - Variation in somaclones (somatic cells of plants)
Somaclonal variation # Basis of somaclonal variation # General feature of Somaclonal variations # Types and causes of somaclonal variation # Isolation procedure of somaclones via without in-vitro method and with in-vitro method with their limitations and advantages # Detection of isolated somaclonal variation # Application (with examples respectively related to crop improvement) # Advantages and disadvantages of somaclonal variations.
https://www.youtube.com/watch?v=IZwrkgADM3I
Also watch, Gametoclonal variation slides to understand, how to changes occur in gametoclones of plants.
https://www.slideshare.net/SharmasClasses/gametoclonal-variation
Secondary Metabolism is a term for pathways for small molecule and products of metabolism that are not absolutely required for the survival of the organism.
A secondary metabolite has an important ecological function.
Examples include antibiotics, mycotoxins etc.
A process where an embryo is derived from a single somatic cell or group of somatic cells. Somatic embryos (SEs) are formed from plant cells that are not normally involved in embryo formation.
Embryos formed by somatic embryogenesis are called Embryoids.
The process was discovered for the first time in Daucas carota L. (carrot) by Steward (1958), Reinert (1959).
Pharmacognosy
Final year B.Pharm
University of Mumbai
Phenylpropanoids are a diverse group of natural products composed of thousands of different compounds, synthesized from the primary metabolites, phenylalanine or tyrosine amino acids, through a series of enzymatic reactions. ... 4-Coumaryl Co-A serves as the common precursor to flavonoid and phenolic acids biosynthesis.
Metabolites, Secondary metabolites are derived from primary metabolites, Why secondary metabolites, Phenolics, Terpenoids, Alkaloids, Special nitrogen metabolites, Cuticular compounds .The major classes of these found in plants
secondary metabolites of plant by K. K. SAHU SirKAUSHAL SAHU
METABOLITES : Introduction . . .
The chemical compounds produced by plants are collectively called as phytochemicals.
Primary metabolites – participating in nutrition and metabolic processes inside the plant.
Secondary metabolites – those chemical compounds that do not participate in metabolism of plants but influencing the
ecological interactions between the plant and its environment.
The presentation gives overview of production of secondary metabolites using callus culture as well as tissue culture techniques. Various batch and continuous culturing process are described on the basis of secondary metabolite to be synthesised.
Phenyl propanoid pathway by kk sahu sirKAUSHAL SAHU
SYNOPSIS
INTRODUCTION
HISTORY
DEFINITION
PRIMARY VS SECONDARY PLANT METABOLISM
SECONDARY METABOLITES
PHENOLIC COMPOUND
PHENYLPROPANOID PATHWAY METABOLITES
PHENYLPROPANOID BIOSYNTHESIS
BIOCHEMICAL PATHWAYS TO PHENOLIC CLASSES
SOME IMPORTANT PRODUCTS OF PHENYLPROPANOID PATHWAY
LIGNANS AND LIGNINS
FLAVONOIDS
METABOLIC ENGINEERING OF PHENYLPROPANOID PRODUCTION
BIOTECHNOLOGICAL APPLICATIONS
CONCLUSION
REFERENCES
plant pathogen interaction
different types of pathogens
gene for gene hypothesis
direct receptor model
Elicitor receptor model
suppersor repressor model
gaurd hypothesis
Somaclonal Variation in Plant tissue culture - Variation in somaclones (somatic cells of plants)
Somaclonal variation # Basis of somaclonal variation # General feature of Somaclonal variations # Types and causes of somaclonal variation # Isolation procedure of somaclones via without in-vitro method and with in-vitro method with their limitations and advantages # Detection of isolated somaclonal variation # Application (with examples respectively related to crop improvement) # Advantages and disadvantages of somaclonal variations.
https://www.youtube.com/watch?v=IZwrkgADM3I
Also watch, Gametoclonal variation slides to understand, how to changes occur in gametoclones of plants.
https://www.slideshare.net/SharmasClasses/gametoclonal-variation
Secondary Metabolism is a term for pathways for small molecule and products of metabolism that are not absolutely required for the survival of the organism.
A secondary metabolite has an important ecological function.
Examples include antibiotics, mycotoxins etc.
A process where an embryo is derived from a single somatic cell or group of somatic cells. Somatic embryos (SEs) are formed from plant cells that are not normally involved in embryo formation.
Embryos formed by somatic embryogenesis are called Embryoids.
The process was discovered for the first time in Daucas carota L. (carrot) by Steward (1958), Reinert (1959).
Pharmacognosy
Final year B.Pharm
University of Mumbai
Phenylpropanoids are a diverse group of natural products composed of thousands of different compounds, synthesized from the primary metabolites, phenylalanine or tyrosine amino acids, through a series of enzymatic reactions. ... 4-Coumaryl Co-A serves as the common precursor to flavonoid and phenolic acids biosynthesis.
A preliminary study on the effects of ozone on induction of resistance in Cic...iosrjce
The potential for ozone to damage vegetation has been known for over 30 years, but it is only over
the last decade that its impacts have become of concern in India and other countries. It is now clearly
established that ozone, at the ambient concentrations can cause a range of effects including visible leaf injury,
growth and yield reductions, and altered sensitivity to biotic and abiotic stresses. Research in recent years has
advanced our understanding of the mechanisms underlying ozone effects on agricultural crops, and to a lesser
extent on trees and native plant species. A study was conducted to evaluate the consequence of application of
ozone for a diminutive period repeatedly on germinated seedlings of Cicer arietinum and Trigonella foenum.
The seedlings were exposed to different concentrations of ozone (5 ppm and 10 ppm) for different time intervals
(5 min, 10 min, 15 min and 20 min) per day for three days. Ozone exposed and untreated (control) plants were
used for biochemical analysis. These include chlorophyll content, total phenol content and phenylalanine
ammonia-lyase assay (PAL). This study has revealed that increase in the ozone concentration and exposure time
enhances the production of soluble phenol contents, PAL activity and reduces the chlorophyll content compared
to control, seedlings.
AN INTRODUCTION TOPLANT SECONDARY METABOLITES :ITS APPLICATIONSSupriya Sankranthi
This presentation is about different types of secondary metabolites produced by the plants and thier applications in different fields like medicine,drugs,cosmetics and perfumery,plant defense,role in ecological balance,textile industries.
Pigments or Biological Pigments can be simply defined as Biochromes or Pigments. These are the substances that are produced by living organisms and have a color that results from the color absorption techniques.
Defensins: Antimicrobial peptide for the host plant resistancesnehaljikamade
Since the beginning of the 90s lots of cationic plant, cysteine-rich antimicrobial peptides (AMP) have been studied. However, Broekaert et al. (1995) only coined the term “plant defensin,” after comparison of a new class of plant antifungal peptides with known insect defensins. From there, many plant defensins have been reported and studies on this class of peptides encompass its activity toward microorganisms and molecular features of the mechanism of action against bacteria and fungi. Plant defensins also have been tested as biotechnological tools to improve crop production through fungi resistance generation in organisms genetically modified (OGM). Its low effective concentration towards fungi, ranging from 0.1 to 10 μM and its safety to mammals and birds makes them a better choice, in place of chemicals, to control fungi infection on crop fields. Herein, is a review of the history of plant defensins since their discovery at the beginning of 90s, following the advances on its structure conformation and mechanism of action towards microorganisms is reported. This review also points out some important topics, including: (i) the most studied plant defensins and their fungal targets; (ii) the molecular features of plant defensins and their relation with antifungal activity; (iii) the possibility of using plant defensin(s) genes to generate fungi resistant GM crops and biofungicides; and (iv) a brief discussion about the absence of products in the market containing plant antifungal defensins.
RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression, typically by causing the destruction of specific mRNA molecules. Historically, it was known by other names, including co-suppression, post-transcriptional gene silencing (PTGS), and quelling. Only after these apparently unrelated processes were fully understood did it become clear that they all described the RNAi phenomenon. Andrew Fire and Craig C. Mello shared the 2006 Nobel Prize in Physiology or Medicine for their work on RNA interference in the nematode worm Caenorhabditis elegans, which they published in 1998. Since the discovery of RNAi and its regulatory potentials, it has become evident that RNAi has immense potential in suppression of desired genes. RNAi is now known as precise, efficient, stable and better than antisense technology for gene suppression. Two types of small ribonucleic acid (RNA) molecules – microRNA (miRNA) and small interfering RNA (siRNA) – are central to RNA interference. RNAs are the direct products of genes, and these small RNAs can bind to other specific messenger RNA (mRNA) molecules and either increase or decrease their activity, for example by preventing an mRNA from producing a protein. RNA interference has an important role in defending cells against parasitic nucleotide sequences – viruses and transposons. It also influences development.
The simplest virions consist of two basic components: nucleic acid (single- or double-stranded RNA or DNA) and a protein coat, the capsid, which functions as a shell to protect the viral genome from nucleases and which during infection attaches the virion to specific receptors exposed on the prospective host cell.
Rhizobia are symbiotic diazotrophs (prokaryotic organisms that carry out dinitrogen fixation) that form a symbiotic association with legumes. This association is symbiotic in that both the plant and rhizobia benefit. The plant supplies the rhizobia with energy in the form of amino acids and the rhizobia fix nitrogen from the atmosphere for plant uptake. The reduction of atmospheric dinitrogen into ammonia is the second most important biological process on earth after photosynthesis (Sylvia, 2005). The actual process of dinitrogen fixation can only be carried out by diazotrophs that contain the enzyme dinitrogenase. Nitrogen is the most critical nutrient needed to support plant growth. Unfortunately, atmospheric dinitrogen (78% of air we breathe) is extremely stable due to triple bonds which can only be broken by energy intensive ways. These include electrical N2 fixation by lightning where oxides of N come to ground with rain, the Haber-Bosch process in industrial fertilizer production, and biological N2 fixation in legumes by bacterial symbionts such as Rhizobium etli. Biological fixation of nitrogen was the leading form of annual nitrogen input until the last decade of the 20th century (Russelle, 2008). It is gaining attention once again as sustainability becomes a central focus to feed a world population of over 7 billion people.
Soil organic matter has long been recognized as one of the most important components in maintaining soil fertility, soil quality, and agricultural sustainability. The soil zone strongly influenced by plant roots, the rhizosphere, plays an important role in regulating soil organic matter decomposition and nutrient cycling. Processes that are largely controlled or directly influenced by roots are often referred to as rhizosphere processes. These processes may include exudation of soluble compounds, water uptake, nutrient mobilization by roots and microorganisms, rhizosphere-mediated soil organic matter decomposition, and the subsequent release of CO2 through respiration. Rhizosphere processes are major gateways for nutrients and water. At the global scale, rhizosphere processes utilize approximately 50% of the energy fixed by photosynthesis in terrestrial ecosystems, contribute roughly 50% of the total CO2 emitted from terrestrial ecosystems, and mediate virtually all aspects of nutrient cycling. Therefore, plant roots and their rhizosphere interactions are at the center of many ecosystem processes. However, the linkage between rhizosphere processes and soil organic matter decomposition is not well understood. Because of the lack of appropriate methods, rates of soil organic matter decomposition are commonly assessed by incubating soil samples in the absence of vegetation and live roots with an implicit assumption that rhizosphere processes have little impact on the results. Our recent studies have overwhelmingly proved that this implicit assumption is often invalid, because the rate of soil organic matter decomposition can be accelerated by as much as 380% or inhibited by as much as 50% by the presence of live roots. The rhizosphere effect on soil organic matter decomposition is often large in magnitude and significant in mediating plant-soil interactions.
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into various chemical forms as it circulates among the atmosphere and terrestrial and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is nitrogen, making it the largest pool of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems. The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
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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.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
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
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
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.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...
Sandesh renew doc ppt
1.
2. “Role of Phenols in plant defense”
Major Guide
Dr. R. W. Ingle
Associate Professor
Department of Plant Pathology
PGI, Dr. P.D.K.V., Akola
Seminar Incharge
Dr. S. S. Mane
Professor & Head of
Department
Department of Plant Pathology
PGI, Dr. P.D.K.V., Akola
Speaker
Mr. S. V. Pawar
Ph. D (Ag.) Plant Pathology
Department of Plant Pathology
PGI, Dr. P.D.K.V., Akola
3. CONTENTS
Introduction
What are phenolics?
Biosynthesis of phenols
Classification of phenolics
Functions of phenolics
Role of phenols in plant defense
Case Study
Conclusion
4. Introduction
Phenolic compounds are the most widely distributed secondary
metabolites, ubiquitously present in the plant kingdom.
They are of great interest for plants, animals and humans. Many of
their functions in plants are related to structure, protection, adaptation
to environment, and interaction with various biotic and abiotic factors.
The first step of the defense mechanism in plants involves a rapid
accumulation of phenols at the infection site (Matern and
Kneusal,1988).
The role of phenolic compounds in defense is related to their
antibiotic, antinutritional or unpalatable properties. Phenolic
compounds have been shown to play a role in both active and passive
forms of defence.
5. Environmentally induced as well as genetically controlled.
This represents one mean of self-protection.
Most classes of phenolic compounds have been shown to be
involved in defense, and these include simple hydroxybenzoic acid,
free and conjugated hydroxycinnamic acids, coumarins, flavonoids
and stilbenes etc.
Depending on the plant species, the types of phenol that are
implicated in defense differ greatly.
This high diversity of phenolics could represent a genuine system
used by plants against multivariable environmental constraints for
their survival and growth including relationships between the plant
and their neighbouring organisms.
6. Major pathways of secondary-metabolite biosynthesis and their interrelationships with primary metabolism
Source: Taiz and Zeiger (2010)
7. SECONDARY METABOLITES
Terpenes
Terpenes derived from
the C5 precursor
Isopentenyl diphosphate
(IPP)
Monoterpenes
Sesquiterpene
Diterpenes
Triterpenes,steroids,
saponines
Phenolics
Phenolics-shikimate
pathway or malonate /
acetate pathway
Flavanoids
Polyacetylene
Polyketides
Phenylpropanoids
Nitrogen containing
compounds
Alkaloids-derived from
amino acids
Alkaloids
Non protein amino
acids
Amines
Cyanogenic glycosides
8. What are phenolic compounds?
The terms ‘phenol’ and ‘polyphenol’ can be defined chemically as
substances that possess an aromatic ring bearing one (phenol) or
more (polyphenol) hydroxyl substituents.
Synthesized via two different routes:
The shikimate pathway (in plants)
The acetate-mevalonate pathway (in fungi and
bacteria)
They are heterogeneous group.
Some are water soluble only in organic solvents
Some are water soluble carboxylic acids and
glycosides
Some are insoluble polymer
Many serves as defense compounds against herbivores and
pathogens
Other function in attracting pollinators and fruit dispensers
9. Occurrence of phenolics
They are usually found as esters or glycosides rather than as free
compounds.
Polyphenols (relatively hydrophilic) usually accumulate in the
central vacuoles of guard cells, epidermal cells and the
subepidermal cells of leaves and shoots.
Some are found covalently linked to the plant cell wall (lignin)
and some found in waxes (related to lipidic structures) or on the
external surfaces (cuticle) of plant organs (Lattanzio et al., 2006).
Biosynthesis of phenolic compounds occurs at various sites in
plant cells, such as the chloroplasts, the cytoplasm and the
endoplasmic reticulum membrane.
10. Biosynthesis of phenolics
Shikimic acid pathway converts simple carbohydrates into aromatic amino acids.
Not present in animals. Mostly derived from cinnamic acid formed from
phenylalanine by phenylalanine ammonia lyase (PAL) enzyme
Source: Taiz and Zeiger (2010)
11. Important enzymes
Polyphenol oxidases
Peroxidases
PAL (Phenyl
Ammonia Lyase)
• Oxidises phenols to quinones-
bactericidal and fungicidal
• Oxidative detoxification of pathogen
phytotoxins
• Increases polymerization of the
phenols into lignins- the complex
phenols
• Key enzyme for the synthesis of
phenols, phytoalexins and other
defense related chemicals.
15. Significance of phenolic compounds
UV sunscreen
Signal compounds
Pigmentation
Plant growth
Plant defense
16. UV sunscreen
Phenolic compounds act as a screen
inside the epidermal cell layer by making
adjustments to the antioxidant systems at
both cell and whole organism level.
Flavonols are involved in UV screening
due to their strong absorbance in
UV-A (325-400nm) and UV-B(280-325nm)
wavelengths.
17. Phenolics as signal compounds
Polyphenols enter the soil mainly as leachates - directly affect the
rates of decomposition and nutrient cycling.
Allelopathic effects -Examples:
1. p-Hydroxy benzoic acid , p-coumaric acid (present in leaves),
2. Quercetin, juglone (present in leaves, bark and root exudates)
3. Catechin , sorgoleone (found in rhizosphere and root exudates)
Symbiosis – Legumes & Rhizobium nodulation by flavonoid
Apigenin, luteolin
19. Phenolics as pigments
An important role of flavonoids is to serve as visual signals by
acting as pigments in fruits and flowers.
To attract animals as pollinators in flowers,
To attract animals to eat the fruits and help in seed dispersal.
Anthocyanins and anthocyanidins - red, blue and purple
colors in plants.
Chalcones and aurones are two classes of flavonoids that
contribute to yellow flower colour in a number of plants. Eg:
yellow carnation, snapdragon.
SnapdragonCarnation
20. Chrysanthemum, Pink gentian Calendula, Ipomoea Blue gentian, Evolvulus
Red cabbage Strawberry Blackcurrants
Anthocyanidins
21. Phenolics and plant growth
Cell wall integrity and shape – wall bound phenolic acids like p-
coumaric and ferulic acid acts as reservoir of phenylpropanid units for
lignin biosynthesis.
Flavanoids have role in functional pollen development in petunia
plants.
Phenolic turgorins - gallic acid and gentisic acid,
found in the pulvini in Mimosa pudica L.
- Nyctinastic leaf movement
Seed dormancy and germination
Ferulic acid inhibits germination of seeds of Raphanus sativus
Coumarinic acid found more in rapidly germinating Melilotus alba
24. Phytoanticipins
Phytoanticipins are low-molecular-weight antimicrobial
compounds that are present in plants before challenge by
microorganisms or are produced after infection solely from
preexisting constituents (VanEtten et al., 1995).
J.C.Walker, K.P. Link and H.R.Angell (1929) reported that
catechol and protocatechuic acid in pigmented onion are resistant to
Colletotrichum circinans.
Susceptible Resistant
26. Phytoalexins
Greek word - Phyto = “plant” and alexin = “to ward off”
Low-molecular-weight antimicrobial compounds that are both
synthesized by and accumulated in cells after exposure to
microorganisms.
The concept of phytoalexin theory of disease resistance was first
propounded by Muller and Borger ,1940. (Potato- Phytophthora
infestans).
Phytoalexins have been reported mostly in dicotyledons and in
few monocots such as rice and oat.
Isoflavonoids are common in the Leguminosae. Stilbenes have
been detected in Vitaceae and Leguminosae
27. Phenolic compounds – Post invasion
Phenolic
compound
Plant Pathogen
Pisatin Pea Nectria haematococca
Glyceollin I Soybean Phytopthora megasperma
Avenanthramide A Oats Puccinia coronata f.sp. avenae
Luteolinidin Sorghum Colletotrichum graminicola
Pterostilbene Grapes Plasmopara viticola
Isoflavanoid Green bean Colletotrichum
lindemuthianum
28. Structural defense
• Lignin is the second most abundant
compound in plants. Deposited in secondary
walls of most plant cells.
• Highly branched polymer of
phenylpropanoid groups (C6 – C 3)n
• Often found in vessel elements, tracheids,
and stems - Primary structural role.
Secondarily as herbivore deterrent.
• Extremly resistant to microbial degradation
• Increased lignification in cell wall in
response to pathogen infection, is found
especially in the incompatible host-parasite
interaction.
• Fungal cell wall and plant cell wall are
elicitors.
29. Feeding deterrents
Toxic to many herbivores by reducing the growth and survivorship.
Tannins can bind digestion enzymes in the gut of herbivores and also
form complex polymers when bound to proteins which are difficult to
digest, thus decreasing the nutritional value of the plant material.
Antifeedant proanthocyanidin (condensed tannins) in red sorghum
deter birds from feeding on the seed
White sorghum deficient in these compounds is eaten by birds.
Red sorghum – antifeedant
proanthocyanidin
White sorghum – lack
proanthocyanidin
30. Salicylic acid
Systemic Acquired Resistance is the activation of defences in
distal, non-infected parts of the plant.
The concept of SAR was made after the discovery of D. F.
Klessig and colleagues and J. Ryals and co-workers that salicylic
acid, a relative of aspirin, is associated with SAR.
The main components of the SA-mediated pathway leading to
disease resistance appear to be constitutively expressed genes
encoding pathogenesis-related (PR) proteins.
Endogenous regulator of induced resistance directly linked to an
effective concentration of SA in the tissue
34. Changes in phenolic content and PO activity in maize leaf sheaths due to
seed treatment with Pseudomonas fluorescens and/or inoculation with
Rhizoctonia solani f.sp. sasakii Exner. ( Banded leaf and sheath blight)
Treatments
Phenolic content µg
catechol/g
fresh tissue
Peroxidase activity(change in
absorbance: OD/min./g)
Days after inoculation Days after inoculation
1 2 3 1 2 3
P. flurescens 190 193 198 1.76 1.77 1.79
P.flurescens + R. solani 230 235 240 1.81 1.83 1.86
R. solani 130 135 139 1.49 1.52 1.56
Control 120 121 123 1.23 1.23 1.24
CD (0.05) 5.71 6.02 7.21 0.11 0.02 1.10
IARI, New Delhi Sivakumar and Sharma (2003)
35. Advantages & Limitations
Advantages
Ubiquitous in plants
Highly fungitoxic
The oxidized phenolics are much more inhibitory in nature
Defense role in abiotic stress and against insect attack also
Limitations
Although several kinds of phenolics are found in plants, they
may not accumulate to fungitoxic levels during pathogenesis
Successful pathogens overcome the fungitoxic phenolics by
several methods and can cause disease
36. Conclusion
Seed treatment of biocontrol agents like P.fluorescens and T.
asperellum against fungal and bacterial pathogens due to high
production of phenolic compounds , PO, PPO activity .
Resistant genotypes of castor and potato against Fusarium
oxysporum f.sp. ricini and pectobacterium respectively showed
increased PAL activity in both pathogen inoculated and non
inoculated plants.
Cotton leaf curl burewala virus resistant cotton cultivar Ravi
showed higher accumulation of phenolic compounds on inoculation
with the virus.
Foliar application of salicylic acid reduced root knot nematode
population and number of gall formation in tomato plants.
Presoaking of tomato seeds with SA and IAA was found to be
effective for control of complete root parasite Orobanche on tomato
