Validation of abiotic stress responsive transcription factors by over expression in crop plants
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Date
2013-03-19
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University of Agricultural Sciences GKVK, Bangalore
Abstract
Drought, temperature extremes and salinity are the most common abiotic stresses, adversely
affecting plant growth and productivity. Plants activate stress signalling pathways,
biochemical and physiological processes necessary for stress adaptation upon stress
induction. Although stress tolerance is governed by multiple traits, a few traits play a major
role in adaptation. Under drought, traits linked to water mining and water conservation,
water use efficiency and cellular tolerance (CT) to desiccation are considered to be relevant.
In this study, attempts have been made to improve CT in drought hardy crop, peanut (Arachis
hypogaea, cv. TMV2) and susceptible crop, sunflower (Helianthus annuus, IB20) by coexpressing
stress-responsive transcription factors (TFs, namely, AtDREB2A, AtHB7 and
AtABF3), the major proteins associated with gene expression. Transgenic crops showed
increased tolerance to drought, salinity and oxidative stresses compared to wild type.
Simultaneous expression of three TFs induced the expression of various stress responsive
genes including detoxifying enzymes, protein kinase, RD29a, LEA and chaperons indicating
that co-expression of TFs can be a good strategy to improve stress tolerance by activating
multiple pathways.
Attempts have also been made to prospect candidate TFs from drought hardy crop, peanut,
and three different TFs, namely, AhZinc finger, AhBTF3 and AhNFYA7 were cloned from
cDNA and functionally validated under different stresses by over expression in model plant,
tobacco. AhZinc finger overexpression resulted in an increased expression of detoxifying
enzymes leading to enhanced tolerance to heavy metal stress. AhBTF3 transgenic plants
showed better phenotype under mannitol- and NaCl-induced stresses. Similarly, AhNFYA7
transgenic plants exhibited increased tolerance under DTT- and tunicamycin-induced ER
stresses. The study demonstrated that the three genes cloned have relevance in improving
cellular tolerance under stressful conditions.
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