Double roles of light-harvesting chlorophyll a/b binding protein TaLhc2 in wheat stress tolerance and photosynthesis

Abstract

Light-harvesting chlorophyll a/b binding proteins are encoded by nucleus genes and widely involve in capturing light energy, transferring energy, and responding to various stresses. However, their roles in wheat photosynthesis and stress tolerance are largely unknown. Here, Triticum aestivumlight-harvesting chlorophyll a/b binding protein TaLhc2 was identified. It showed subcellular localization in chloroplast, contained light responsive cis-elements, and highly expressed in green tissues and down-regulated by multiple stresses. TaLhc2 promoted the colonization of hemi-biotrophic pathogen; further analysis showed that TaLhc2 strengthened BAX-induced cell death, enhanced the ROS accumulation, and up-regulated pathogenesis-related genes; those results suggested that TaLhc2 has adverse influence on host immunity and function as a susceptible gene, thus host decreased its expression when faced with pathogen infection. RT-qPCR results showed that TaLhc2 was down-regulated by drought and salt stresses, while TaLhc2 improved the ROS accumulation under the two stresses, suggesting TaLhc2 may participate in wheat responding to abiotic stress. Additionally, TaLhc2 can increase the content of total chlorophyll and carotenoid by 1.3 % and 2.9 %, increase the net photosynthetic rate by 18 %, thus promote plant photosynthesis. Conclusively, we preliminarily deciphered the function of TaLhc2 in biotic/abiotic stresses and photosynthesis, which laid foundation for its usage in wheat breeding.

Keywords: Photosynthesis; ROS accumulation; Susceptible gene.