Physiological Mechanisms Of Overexpression Of Maize GLK Genes In Improving Photosynthesis And Reducing Photoinhibition In Rice

Food security is threatened by the growing population and accelerating climate change worldwidely.As one of the most important major food stape,the yield increase in recent years had hit a ceiling by optimization on breeding and cultivating practice.Photosynthesis is the basis and a major determination of crop yield.Photosynthetic efficiency has been considered as an effective approach for improvement of crop yield potential under agricultural field conditions.Photoinhibition caused by excessive radiance leads to a decrease in the photosynthetic efficiency and affects field production to a great extent.Nuclear-encoded GOLDEN2-LIKE(GLK)transcription factors regulate some of the earliest steps by activating target genes encoding chloroplast-localized and photosynthesis-related proteins.Here we show that constitutive expression of maize GLK genes in rice leads to enhanced levels of chlorophylls and pigment-protein antenna complexes,and that these increases lead to improved light harvesting efficiency via photosystem ? in field-grown plants.Increased levels of xanthophylls further buffer the negative effects of photoinhibition under high or fluctuating light conditions by facilitating greater dissipation of excess absorbed energy as heat.Significantly,the enhanced photosynthetic capacity of field-grown transgenic plants resulted in increased carbohydrate levels and a 30-40%increase in both vegetative biomass and grain yield.ZmG2 gene exhibited better performance compared with ZmGLK1,especially under high light conditions.This research revealed the new function and regulation mechanism of GLK genes in coordinately regulating photosynthesis effciency and yield improvement,which would provide important theoretical basis and feasible way in agricultural production.