seminar notes

1. Root exudation-definition
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1. Root exudation-definition
→ are the chemicals secreted into the soil by roots
2. Exudation
→ leaking of substances
3. Why do plants exude?
→ Root exudation mediates positive interactions (symbiosis) and negative interactions (allelopathy, defense against fungi and bacteria). Also mediates micronutrient uptake, detoxification, and penetration of soil by the root tip.
4. What do plants exude?
→ Different compounds like: amino acids, carbohydrates, organic acids, flavonoids, lignins, anthocyanins, sterols, proteins and enzymes
5. How do plants exude?
→ The two main mechanisms for active exudation are vesicular transport ( originates in the ER/Golgi, mediates exudation of proteins, polysaccharides and secondary metabolites and through discharging of contents-exocytosis) and through membrane-bound transporters
6. How do we study exudation?
→ Natural variation and inhibitors can be used to study exudation. (benzoxazinoid exudation in maize which attracts beneficial bacteria to maizei roots - collection—analysis
• Complex networks have a structure in which ...
different groups can be distinguished (communities), which have certain qualities in common.
• Network data can be combined with...
other information to learn more about groups and nodes
• Individual nodes may have a lot or few connections. Highly connected nodes are important for ...
network stability and spreading information.
• The number of the edges shows the ...
poisson distribution
• What is a network?→ Networks are graphical, often simplified representations (models) of complex relationships. They can be undirected (know only the nodes that are connected) or directed ( we know the way they are connected)• Community is a group of ...network nodes more densely connected to each other than to the rest of the network• Clique is a ...completely connected set of nodes.• Stress resistance can ...• Stress resistance can greatly increase yield even in optimized production systems.• PAMP (pathogens-associated molecular patterns) receptors can be ...• plant lineage or family specific.• PAMP receptors retain their signaling capacity when ..transgenically expressed.• R-genes function whentransferred with the same species or two related species attached by the same pathogen.• S-FACTOR MUTANTS ARE RESISTANT TOBIOTROPHiC PATHOGENS• Susceptibility genes are involved in controlling defense or ...in processes required by the pathogen from the host• Susceptibility factors help findnew susceptibility/resistance factorsLoss of susceptibility s genes can be ...for the plantscostly• ..... of s genes alleles may result in durable disease resistanceTargeted editing• Pathogen induced knock down of s genes may result in ...durable disease resistance.• The level of plant hormone is regulated by:the rate of biosynthesis, modification/degradation, release of conjugates (deconjugation→ release of active hormones of conjugates)• Important means of modification include (for inactivation):glycosylation, hydroxylation, esterification, conjugation with amino acids. (GHEC)• Glycosylation is catalyzed byenzymes belonging to the UGT family (UDP-glucosyl transferases)• Glucosides may represent ...a storage form of phytohormons• Glucosides may be further derivatised bymalonylation• Why is it important to develop genetic and biotechnological approaches to modulate SAM activity?→ Economic importance. Light harvesting potential, number/quality of flowers, fruits, seeds, overall biomass formation, influence on cultivation effort, biotic/abiotic stress resistance.• Coordination of meristem activity: 1) Meristem size: plants with reduced cytokinin levels have ...smaller shoot meristem and produce less leaves. (cytokinin controls shoot meristem size) Cytokinin controls the expression of the stem cell identity factor WUSCHEL. (CLAVATA genes negative regulators of shoot meristem size)• WUS/CLV → keeps the ... in balancesize• 2) Spatial control of organ formation (......): Existing primordia delivers an inhibiting signal in which new primordia cannot form. (Auxin is involved → a local auxin maximus is required for ...... Also auxin is transported by .... in a polar fashion way, contributing to organ initiation. Existing leaf primordial remove..... in their area.phyllotaxis organogenesis PIN1 transporters auxin• 3) temporal control of organ formation (...): miRNA156 controls ...... and regulate leaf formation rate.(overexpression → .......)Plastochron SPL transcription factors more leaves• AMP1 and CYP7 are enzymes which ...produce a signal, which inhibits leaf formation.(regulation of leaf formation rate) → If you mutated them → leaf formation!• Plant and animal members of the .......adopted unrelated functions.GCPII family of proteases• Hyperphyllin might act as a.... •chemical inhibitor of AMP1 and is an important tool to further characterize the function of this enzyme. (it increase leaf formation)HP represents a leading compound for a novel class of plant growth regulators to ....enhance leaf formation rate• Systemic acquired resistance (SAR) is induced in ...the systemic healthy tissues of locally infected plantsAlthough dependent on SA in dicots, SAR-like immunity in barley is associated with : (4)JA, ABA, and WRKY and ERF transcription factors (not with SA)• A possible role of transcription factors in barley SAR-like immunity will be evaluated using...CRISPR-Cas9-generated barley mutants• How do WRKYs and ERFs affect SAR-like immunity?→ Gene promoter binding sites, target genes, spatio-temporal organisaton.• Induced systemic resistance (ISR) in induced in the above-ground healthy tissues of plants in interaction with :beneficial organisms in the rhizosphere• The plant-associated microbiome contributes to ISR and most likely SAR, and is itself affected by ...inducible immunity• SA mediates resistance to ..........and is required for SAR. JA mediates resistance to necrotrophic pathogens and insects and is required for ...bio trophic pathogens ISR (Induces systematic resistance)Epigenetics describe modifications that cause changes in gene expression that are stably transmitted during .....but that do not involve differences in the underlying DNA sequence.mitosis or meiosis,In eukaryotes, most known epigenetic mechanisms are chromatin based, and may involve still poorly defined combinations of :post-translational histone modifications and histone variants, small or long non-coding RNAs, and DNA methylation.Epigenetic's examines proteins' interactions with DNA and its associated components, including histones and various modifications such as ...methylation, which alter the rate or target of transcription.• How prevalent is epigenetic inheritance in natural and domesticated populations? →Many of the differentially methylated regions DMRs, are also variable in natural populations• How stable is it across generations?→ Experimentally induced variation in DNA methylation can be inherited over many generations and affect phenotypes independently of genetic changes.• How much of the heritability of important plant traits does it explain?→ Several DMRs, acts are quantitative trait loci (QTL-EPI) and are accounting for the 60-90% of the heritability for two complex traits in plants. Flowering time and primary root length. These QTL are reproducible and can be subjected to artificial selection.• Can epigenetics variation be subject to artificial or natural selection?→ YES, the detected QTL have all the necessarily properties to become targets of natural or artificial selection.• If yes, what are its implications for plant breeding or evolutionary adaptation?Contribute to quantitative variation in flowering timeNO has a dual role as a component of the smog and ....as a signaling molecule in animals and plants• NO is a small, ubiquitous and gaseous signaling molecule involved in the regulation of a variety of physiological processes in plants such as :seed germination, root architecture, vegetative growth, flowering, fruit ripening, senescence and biotic and abiotic stress responsesNO is classified into the reactive nitrogen species (RNS) as a free radical highly reactive with several molecules :(oxygen, radical superoxide, thiol groups)NO affects proteins by two post-translational modifications (PTMs):S-nitrosylation (No binds to Cys residue) and Nitration (NO2 binds to Tyr residue)These specific PTMs modify the function of the proteins affecting theirconformation, activity, stability, subcellular localization and interaction with other proteins into the cell to regulate different processesABI5 is a master repressor of ....of seed germination... TRIGGERS ABI5 DEGRADATION TO PROMOTE SEED GERMINATIONS-NITROSYLATION