Ectopic expression of C photosynthetic pathway genes improves carbon assimilation and alleviate stress tolerance for future climate change.

Alteration in atmospheric carbon dioxide concentration and other environmental factors are the significant cues of global climate change. Environmental factors affect the most fundamental biological process including photosynthesis and different metabolic pathways. The feeding of the rapidly growing world population is another challenge which imposes pressure to improve productivity and quality of the existing crops. C plants are considered the most productive, containing lower photorespiration, and higher water-use & N-assimilation efficiencies, compared to C plants. Besides, the C-photosynthetic genes not only play an important role in carbon assimilation but also modulate abiotic stresses. In this review, fundamental three metabolic processes (C, C, and CAM) of carbon dioxide assimilation, the evolution of C-photosynthetic genes, effect of elevated CO on photosynthesis, and overexpression of C-photosynthetic genes for higher photosynthesis were discussed. Kranz-anatomy is considered an essential prerequisite for the terrestrial C carbon assimilation, but single-celled C plant species changed this well-established paradigm. C plants are insensitive to an elevated CO stress condition but performed better under stress conditions. Overexpression of essential C-photosynthetic genes such as , , and - in C plants like , tobacco, rice, wheat, and potato not only improved photosynthesis but also provided tolerance to various environmental stresses, especially drought. The review provides useful information for sustainable productivity and yield under elevated CO environment, which to be explored further for CO assimilation and also abiotic stress tolerance. Additionally, it provides a better understanding to explore C-photosynthetic gene(s) to cope with global warming and prospective adverse climatic changes.