Proteomics and molecular biology of abiotic stress response and tolerance
Control of gene expression during development or adaptation to an environment involves perception and integration of cellular and environmental signals, the regulators. Whereas the roles of proteins as gene regulatory factors are well established, the functions of regulatory RNA molecules in development are just beginning to emerge. Among these regulatory RNAs, MicroRNAs (miRNAs) have generated considerable excitement recently. A growing body of evidence suggests that these ∼21-nucleotide (nt) noncoding RNA molecules play crucial roles as regulators of gene expression in eukaryotes. The regulatory proteins, nevertheless, also regulate their expression.
As proteins mediate all the metabolic activities of living organism, it is likely that the concerned genes would have a distinctly different expression patter in the plant under contrasting environmental situation. Similarly, two cultivars contrast for stress tolerance or yield potential would have set of differentially expressing genes influencing the trait. Identification of the differentially expressed genes for a trait may throw information on the biochemical basis of phenotype displayed. Study of expression pattern of the differentially expressing genes for a environmental trait across plant species contrast for the trait would further shortlist the genes associated with the trait. The work is also being extended to crop cultivars sensitive and tolerant to salinity. Among the crop cultivars, rice provides extensive variability for both yield potential and abiotic stress tolerance. Besides, its panicle architecture is such that the crop yield is reflected in terms of spatial positioning of spikelets in the position. Hence, the plant provides opportunity to look into differential expression of genes for a trait, particularly yield or stress-induced loss of yield, in the same plant.
With regard to survival of plants or yield potential of crop plants under an environmental condition or cultivar-specific yield potential of crop plants, the following pertinent questions thus surface: 1) whether the trait is governed by one or more effectors or isoform-specific effector and how the effectors are regulated, 2) if isoform-specific effector(s), how the expression the individual isoforms is regulated, 3) what is the nature of the environmental signal that activates the regulatory network. These questions are being looked into through genomics and proteomics approaches under the following heads:
a) Identification and functional characterization of the key effectors and regulators making a plant salt tolerant and those leading to poor grain filling in rice
b) Understanding transcriptional regulation of effectors and regulators and their link to environmental signals.
c) QTL identification for yield and abiotic stress tolerance.
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