A salt-tolerant chloroplastic FBPase from Oryza coarctata confers improved photosynthesis with higher yield and multi-stress tolerance to indica rice

C-3 photosynthesis in rice is dependent on regeneration of Ribulose 1,5-bisphosphate (RuBP), the CO2 acceptor which is largely determined by the Fructose 1,6-bisphosphatase (FBPase) function in the chloroplast. Abiotic stress affects this function negatively impacting the decline in the photosynthetic potential of crop plants. In the present work the PcCFR gene, coding for a salt-tolerant chloroplastic FBPase, from Oryza coarctata (Roxb.) Tateoka, was introduced into the cultivated rice (Oryza sativa var. indica IR64). The homozygous transgenic PcCFR plants performed better than the untransformed lines in terms of overall plant growth, photosynthetic performances and grain yield under normal as well as under salt and different abiotic stress conditions. Under salinity, drought and cold stress PcCFR lines showed tolerance through emergence of new leaves, improved photosynthetic performance and overall growth rate. The cumulative results suggested that the overexpression of salt-tolerant FBPase (PcCFR) protein in the transgenic rice helps to keep the photosynthetic cycle by unabated generation of RuBP that retains better light harvesting capacity of the leaves under stress. It is presumed that this will provide an insight into the growth and development during abiotic stress by inducing an interaction among different sugars derived from photosynthetic carbon metabolism as well. Key message The transgenic IR64 plants, over-expressing a salt-tolerant chloroplastic FBPase from Porteresia coarctata, showed multi-stress tolerance, improved plant phenotype, electron transport rate, transpiration rate, photosynthetic efficiency and grain yield under salinity.