Heterologous expression of a chimeric gene, OsDST-SRDX, enhanced salt tolerance of transgenic switchgrass (Panicum...

Overexpression of OsDST-SRDX chimeric gene in switchgrass promotes plant growth and improves the salt tolerance of transgenic switchgrass by improving its antioxidative ability. Switchgrass (Panicum virgatum L.) is a forage and model feedstock plant. To avoid competing with crops in arable land utilization, improving salt tolerance of switchgrass is required to use marginal saline land for switchgrass production. To improve salt tolerance of switchgrass, a chimeric DROUGHT AND SALT TOLERANCE (DST) gene OsDST-SRDX was constructed using the Chimeric REpressor gene-Silencing Technology (CRES-T), and introduced into switchgrass genome by Agrobacterium-mediated transformation. Compared to wild-type (WT) plants, OsDST-SRDX transgenic (TG) switchgrass plants showed wider leaves and thicker stems. They performed better under salt stress, had higher relative leaf water content, lower electrolyte leakage and lower malondialdehyde (MDA) content, and accumulated less Na⁺ and more K⁺ than WT controls. The transgenic plants had also higher activities of antioxidant enzymes associated with suppressed expressing of genes in H₂O₂ homeostasis, including glutathione S-transferase (GST2, GST6), cytochrome P450, peroxidase 24 precursor, and induced expressing of CAT and SOD under salt stress to eliminate excess H₂O₂. Our results indicate that overexpression of the chimeric gene OsDST-SRDX improves salt tolerance of switchgrass, a C₄ biofuel crop.