ENHANCING OXIDATIVE STRESS TOLERANCE IN AEROBIC RICE (Oryza sativa L.); VALIDATION OF ROS SCAVENGING ENZYMES BY TRANSGENIC APPROACH AND IDENTIFICATION OF OXIDATIVE STRESS SPECIFIC UPSTREAM GENES
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Date
2015-09-28
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Rice crop grown under aerobic conditions experience moisture stress between
irrigations resulting in oxidative stress, which is a major constraint to realize potential
yields. One of the most common strategy to improve tolerance to oxidative stress is by
overexpressing either single or multiple antioxidant genes by transgenic approach. The
second strategy is to overexpress the upstream regulatory genes, mainly transcription
factors (TFs) specific to oxidative stress. A novel T7 polymerase based multigene
construct consisting of 5 antioxidant genes of the Asada Halliwell pathway viz., SOD,
APX, DHAR, MDHAR and GR was developed and transformed into two selected
aerobic rice genotypes-AC39020 and KMP175 by in planta transformation technique.
Promising lines were identified based on stable integration of transgenes and response to
oxidative stress. In T4 generation 13 lines of each genotype were assessed for tolerance
to oxidative stress, moisture stress and high temperature stress along with grain yield
under moisture stress conditions. The other objective of the study was to identify TFs
associated with oxidative stress. The transcriptomic profile was assessed by microarray
analysis in two contrasting rice genotypes (AC39020-tolerant & BPT5204-susceptible)
subjected to oxidative stress. Among the 918 differentially expressed genes, 38 were TFs
and 2 were kinases. About 20 TFs were shortlisted by extensive in silico analysis which
included spatial expression profile, presence of ROS- elements, meta-analysis and coexpression
matrix. To accurately characterize the stress response of transgenics and
germplasm accessions a novel minilysimeter based phenomics facility was developed.
The facility could monitor and maintain a desired soil moisture status and precisely
control dry down rates. The facility successfully brought out the differences in growth
between the contrasting rice genotypes by maintaining both at 70 per cent FC±5 per cent
Based on the results of the pilot project, a new high through put phenomics facility was
developed with 450 minilysimeters.
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