Differential antioxidative responses to dehydration-induced oxidative stress in core set of foxtail millet cultivars [Setaria italica (L.)]
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Foxtail millet (Setaria italica L.) known as a relatively drought-tolerant crop across the world is grown in arid and semi-arid regions. To the best of our knowledge, no systematic study on drought tolerance screening of foxtail millet germplasm being a drought-tolerant crop has been reported so far. To explore genetic diversity of drought-induced oxidative stress tolerance in foxtail millet, we employed lipid peroxidation measure to assess membrane integrity under stress as biochemical marker to screen 107 cultivars and classified the genotypes as highly tolerant, tolerant, sensitive, and highly sensitive. From this comprehensive screening, four cultivars showing differential response to dehydration tolerance were selected to understand the physiological and biochemical basis of tolerance mechanisms. The dehydration-tolerant cultivars (IC-403579 and Prasad) showed considerably lower levels of lipid peroxidation and electrolyte leakage as compared with dehydration-sensitive cultivars (IC-480117 and Lepakshi), indicating better cell membrane integrity in tolerant cultivars. Correspondingly, tolerant genotypes maintained higher activity of catalase (EC 184.108.40.206), ascorbate peroxidase (APX; EC 220.127.116.11), and glutathione reductase (GR; EC 18.104.22.168) across different time-course period of polyethylene glycol (PEG) treatments in comparison to sensitive ones. The above biochemical results were further validated through quantitative real-time PCR analysis of APX and GR, whose transcripts were substantially induced by PEG treatments in tolerant cultivars. These results suggest that tolerant cultivars possess wider array of antioxidant machinery with efficient ascorbate–glutathione pathway to cope with drought-induced oxidative stress.
KeywordsSetaria italica Dehydration Relative water content (RWC) Lipid peroxidation (LP) Electrolytic leakage (EL) Reactive oxygen species (ROS) Antioxidative enzymes Quantitative real-time PCR (qRT-PCR)
We are grateful to the Director, National Institute of Plant Genome Research (NIPGR) for providing facilities and to University Grants Commission (U.G.C.), Govt. of India for providing UGC-SRF to Ms Charu Lata. We gratefully acknowledge the financial support from the Department of Biotechnology, Government of India (BT/IN/FRG/04/MP/2008), and IB-BMBF, Germany (IND 07/037), for carrying out the present study under the Indo-German bilateral program. We are also thankful to National Bureau of Plant Genetic Resources, Hyderabad, India, for providing the seed material.
Conflict of interest
The authors declare that they have no conflict of interest.
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