The NADP-malate dehydrogenase (SmNADP-mdh), a C4 pathway gene from Suaeda monoica enhanced photosynthesis and biomass yield in C3 plants

Abstract

Enhanced photosynthesis and biomass have been achieved in C 3 plants by over-expressing NADP dependent malate dehydrogenase ( SmNADP-mdh ), a C 4 pathway gene from Suaeda monoica . Over-expression of the SmNADP-mdh improved seed germination, seedling growth and accumulation of pigments, sugar, starch and C H N S elements in transgenic tobacco under in vitro conditions. Transgenic tobacco exhibited higher NADP-MDH activity, membrane stability index, photosynthesis efficiency, improved stomatal conductance, carboxylation efficiency, photosystem II (PSII) operating efficiency, electron transfer rate, photochemical quenching and better accumulation of sugar and starch at elevated (1200 ppm) CO 2 (eCO 2 ). Chlorophyll a fluorescence analysis showed improved pool size, electron transfer, water-splitting activity, photosynthetic performance indexes and efficient working of PSII at eCO 2 in transgenic tobacco over-expressing SmNADP-mdh . The higher expression of antioxidant defence genes indicated better scavenging and lesser accumulation of ROS at eCO 2 . Results suggest the potential of a single-cell C 4 halophytic NADP-mdh gene in the development of smart agriculture to improve the photosynthetic efficiency and biomass yield in C 3 plants. • The SmNADP-mdh transgenic tobacco exhibited higher NADP-mdh activity. • SmNADP-mdh gene improved seed germination and seedling growth. • Transgenic tobacco exhibited higher sugar contents under in vitro conditions. • Transgenic tobacco showed higher photosynthesis and carboxylation efficiency. • Transgenic tobacco showed higher contents of pigments and sugar at eCO 2 .