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

Enhanced photosynthesis and biomass have been achieved in C3 plants by over-expressing NADP dependent malate dehydrogenase (SmNADP-mdh), a C4 pathway gene from Suaeda monoica. Over-expression of the SmNADPmdh 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) CO2 (eCO2). Chlorophyll a fluorescence analysis showed improved pool size, electron transfer, water-splitting activity, photosynthetic performance indexes and efficient working of PSII at eCO2 in transgenic tobacco over-expressing SmNADP-mdh. The higher expression of antioxidant defence genes indicated better scavenging and lesser accumulation of ROS at eCO2. Results suggest the potential of a single-cell C4 halophytic NADP-mdh gene in the development of smart agriculture to improve the photosynthetic efficiency and biomass yield in C3 plants.

Automated summary

Over-expression of the C4 pathway gene SmNADP-mdh can enhance photosynthesis and biomass in C3 plants. Transgenic tobacco with over-expression of SmNADP-mdh showed improved growth and metabolic efficiency, as well as better accumulation of sugars and starch under elevated CO2 concentration. The over-expression of the gene also increased the antioxidant capacity and photosynthetic performance of the transgenic tobacco.