Comparative analysis of ROS-scavenging gene families in finger millet, rice, sorghum, and foxtail millet revealed potential targets for antioxidant activity and drought tolerance improvement

摘要

Antioxidants play a key role in maintaining cell activity in plants and animals by scavenging reactive oxygen species. Hence, it is very important to understand genes associated with antioxidant activity for improving the varieties. In this study, we compared structural and functional aspects of antioxidant genes viz., APX, DHAR, MDHAR, GR, and SOD of two contrasting genotypes viz. GP-1 (low Ca2+) and GP-45 (high Ca2+) of finger millet with other cereal crops such as rice, sorghum, and foxtail millet. The structural analysis shows that all genes are conserved and shares almost the same domains such as ascorbate peroxidase, glutathione dehydrogenase, glutathione reductase, Fe, and Cu-Zn superoxide dismutase domains which play a significant role in antioxidant activity and drought tolerance. These genes were mainly localized in chloroplast and cytoplasm which prove that both are the major ROS-scavenging sites. Furthermore, several putative cis-acting regulatory elements such as AuxRE, DRE, GARE, G-box, GATA-box, MBS, MYBR, and W-box are also studied and found that these genes are involved in defense mechanisms which allow responses against drought stress. Antioxidant activity of these genes was compared using expression analysis in terms of FPKM values and found that the genes of low Ca2+ genotype are highly expressed compared to the genes of high Ca2+ genotype and the genes of rice, sorghum, and foxtail millet. These results revealed that a low Ca2+ genotype of finger millet has higher antioxidant activity in comparison to high Ca2+ genotype and other cereal crops. Based on the results, we hypothesize that these candidate genes could be a target to develop highly antioxidative potential and drought tolerant genotypes of other cereal crops through appropriate breeding approaches.