ROLE OF HELICASE IN STRESS TOLERANCE: AN ANALYSIS THROUGH TRANSGENIC APPROACH IN CROPS
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Date
28-07-14
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University of Agricultural Sciences GKVK, Bangalore
Abstract
Plants are often exposed to diverse environmental cues, among which the abiotic
stressor, drought is the major factor which limits plant growth and productivity. Plants
have evolved various mechanisms and traits to maintain intrinsic cellular tolerance
and improved water relations under drought. Cellular level tolerance is achieved by
several mechanisms and amongst them protein turnover which is affected under
stress, is the most relevant trait to be improved. From this context, stress responsive
RNA helicases which sustain translation assumes significance in sustaining protein
turnover under stress. The present study was aimed to clone and characterise stress
responsive RNA helicases AhRH47 and AhRH68 from stress adapted species
groundnut. AhRH47 is involved in removal of secondary structures at leader sequence
of mRNA. Arabidopsis transgenic plants constitutively overexpressing AhRH47
showed increased protein synthesis under stress and better tolerance under salinity
and mannitol stresses, besides higher survival and biomass production under moisture
stress. A partial sequence of AhRH68 was cloned from groundnut and it showed high
expression under salinity stress. The predicted protein structure suggested that it
associates with spliceosome and plays a role in removing secondary structures in premRNA.
AhRH68 is highly homologous to p68 (Pisum sativum RNA helicase 68).
Groundnut transgenics expressing p68 showed intrinsic cellular tolerance to ethrel
induced senescence, salinity, oxidative and simulated moisture stresses. Further, in T3
generation, transgenics showed superior survival and recovery under temperature
stress, severe moisture stress and oxidative stress at whole plant level. Productivity
was one of the criteria apart from intrinsic tolerance for selection of promising lines.
The promising transgenic lines advanced to T4 generation showed 33% higher
productivity over wild type. From these findings, it suggests that selected p68
overexpressing groundnut transgenic plants are highly productive. Hence, AhRH47
and p68 RNA helicase are potential candidate genes to improve adaptation to abiotic
stress.
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