Roles of zinc in alleviating environmental stress on plant photosynthesis: challenges and future outlook

Considering the current scenarios with regard to increasing global population and climate changes, it is obligatory to enhance agricultural productivity and develop stress-resilient crops. Photosynthesis is the key carbon source for improving plant growth and development. In this way, improving the photosynthesis process by limiting the severe impacts of environmental stress factors is a crucial step to improve crop yields and ensure food security. Several molecular approaches and agronomic practices have been employed or suggested to stimulate the photosynthesis process. Among them, the exogenous supplementation of zinc (Zn) is an ideal candidate to alleviate the deleterious impacts of abiotic stresses by improving the key photosynthetic limiting variables such as stomatal conductance, net photosynthetic rate, light harvesting pigments or chlorophyll fluorescence, photochemical or photosynthetic efficiency, RuBisCo activity, and thylakoid membrane electron transport. Moreover, Zn regulates numerous metabolic processes by activating protein synthesis, photosynthetic traits, auxin biosynthesis, and lipid metabolism. Herein, we have reviewed the potential mechanistic basis utilized by Zn in improving the plant photosynthesis process as well as adaptation to adverse environment conditions such as high or low temperature, drought or flooding, salinity, elevated CO2, and heavy metals. Thus, the final target of this chapter is to achieve the Zn-mediated optimization of photosynthesis status in different plant species under environmental stress conditions. Moreover, we have highlighted the research gaps, potential challenges, and possibilities regarding advance and future research.