STACKING OF UPSTREAM REGULATORY GENES TO CONFER ABIOTIC STRESS TOLERANCE IN RICE (Oryza sativa L.)
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Date
2015-12-03
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Rice cultivation under aerobic condition has phenomenal relevance in terms of saving
water. But reduced water availability and high VPD affecting crop growth and
productivity. Thus it is important to improve adaptation of rice under aerobic condition
by improving water relations and cellular level tolerance (CLT) mechanisms. Improving
CLT to sustain cell metabolic activities has relevance under stress and among several
CLT mechanisms, protein synthesis and stability are crucial. From this context, an
attempt has been made to validate three regulatory genes i.e. Pg47 (Pennisetum glaucum
47, a RNA helicase), OseIF4E (Oryza sativa translational initiation factor 4E) and
PgHSF4 (Pennisetum glaucum heat shock factor 4) involved in protein synthesis and
protection in a model system tobacco. Transgenics expressing single and multigene
cassette showed higher tolerance to diverse stresses viz. salinity, ER, heavy metal,
drought and osmotic stress, besides showing enhanced expression of few stress
responsive genes compared to wild type under stress. However, lines expressing
multigene cassette showed superior phenotype and tolerance over lines expressing single
genes with significantly higher protein content and lesser malondialdehyde level. This
demonstrated the significance of co-expressing more than one stress specific
genes/TFs over single gene. To improve adaptation of rice under semi-irrigated aerobic
conditions rice transgenics co-expressing multigene cassette were developed in the
background of AC39020 genotype having superior water relations. True transformants
were identified based on glyphosate tolerance. The transgenics showed improved
tolerance to salinity, ER and heavy metal stress apart from drought stress. Under
drought stress, many promising transgenic lines showed reduced spikelet sterility and
higher yield compared to wild type. The study provides proof of concept that
maintaining efficient translation and protein protection improves CLT and transgenic
is a potential option to combine or pyramid the relevant traits to improve field level
tolerance.
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