MOLECULAR CHARACTERISATION OF THE VARIABILITY IN CELLULAR LEVEL TOLERANCE IN RICE (Oryza sativa L.). AN ANALYSIS BASED ON METABOLOMICS APPROACH
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Date
2016-10-20
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Aerobic cultivation can save up to 60 per cent of irrigation water in
comparison with lowland rice, concomitant yield loss of upto 40 per cent
is often noticed in aerobic cultivation, which is caused primarily due to
an increased spikelet sterility. Better root systems coupled with higher
cellular level tolerance (CLT) can significantly improve spikelet fertility
under semi-irrigated aerobic condition. Cellular level tolerance (CLT)
associated with production of compatible solutes and metabolites that
reorganize proteins and cellular structures leading to maintenance of leaf
turgor, cellular redox balance and homeostasis. Comprehensive profiling
of solutes and metabolites in rice genotypes with varied level of drought
tolerance and spikelet fertility would pave way in understanding the
biochemical mechanisms at the cellular level and to identify genes
responsible for high CLT under drought conditions. Fingerprint of
biochemical perturbations could also be a reliable method to phenotype
CLT under stress. Metabolite-based genome-wide association study
(mGWAS) has emerged as a powerful alternative forward genetics
strategy. In this study, differentially accumulated metabolites among
drought tolerant and susceptible rice genotypes under well watered and
water stress were measured using high resolution LC-MS. Metabolites
that accumulated with significantly higher abundance in drought
tolerant rice genotype compared to susceptible genotype upon stress
induction were identified as Tolerance Related Induced (TRI) metabolites.
Such TRI metabolites mainly belonged to primary metabolites: sugars,
amino acids and secondary metabolites such as phenylproponoids,
flavonoids and alkaloids. Primary metabolites mainly involved in
synthesis of stress responsive proteins and osmoprotection and
secondary metabolites as antioxidants, Reactive Oxygen Species (ROS)
scavengers, coenzymes, UV and excess radiation screen and also as
regulatory molecules. mGEWAS analysis identified genomic regions
(QTL’s) associated with CLT and regulatory genes governing raffinose and
GABA biosynthesis under drought stress in tolerant genotype.
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