With the intensification of global warming, the frequency and intensity of high-temperature events have increased significantly, and their negative impacts on agricultural production have become increasingly prominent. As a thermophilic crop, rice is highly sensitive to temperature changes during growth and development. Heat stress not only disrupts the stability of the photosynthetic system and reduces carbon assimilation efficiency, but also causes abnormal anther development and decreased pollen viability, ultimately leading to reduced seed-setting rate and sharp yield loss, which seriously threatens national food security. Therefore, dissecting the molecular mechanisms underlying rice thermotolerance and enhancing crop thermotolerance through genetic improvement of key components in the photosynthetic system has become an important research direction to ensure high and stable rice yields under complex environmental conditions.
Recently, the team led by Academician Qian Qian from the China National Rice Research Institute published an online research article in Science Bulletin entitled “Regulation of photosynthesis and ROS homeostasis by Fd1 and FNR1 confers thermotolerant yield stability in rice”. This study elucidated the molecular mechanism by which the photosynthetic electron transport protein Fd1 and its interacting protein FNR1 enhance thermotolerant yield stability in rice under heat stress by stabilizing photosynthesis and reducing reactive oxygen species (ROS) accumulation. It provides important theoretical and technical support for breeding new rice varieties with high thermotolerance, superior quality, and stable yield.
Previous studies by the research team have confirmed that ferredoxin 1 (Fd1) is a core component in rice photosynthetic electron transport and directly participates in carbon assimilation. Loss of function of this gene results in severe seedling lethality in rice. Based on these findings, the team further conducted in-depth research on the Fd1 and revealed its key role and molecular mechanism in regulating rice thermotolerance: under heat stress, the expression of endogenous photosynthetic genes such as Fd1 is repressed, leading to reduced photosynthetic efficiency and restrained assimilation. Overexpression of Fd1 or FNR1 can maintain the expression of photosynthetic genes and stabilize photosynthetic electron transport, thereby retaining relatively stable carbon assimilation flux. Meanwhile, overexpression lines significantly upregulate the expression of genes related to the water-water cycle (WWC), reduce ROS accumulation in anthers, thus protecting pollen viability, improving seed-setting rate, and ensuring thermotolerant yield stability in rice.
To verify the thermotolerant and yield-stable phenotypes conferred by these genes, the research team conducted systematic multi-location field trials and greenhouse experiments over consecutive years in Hangzhou, Wuhan, Chongqing, and Lingshui, effectively bridging basic research under controlled conditions with production practice under complex field conditions. The positive regulatory roles of Fd1/FNR1 in rice thermotolerance and yield stability were further validated in the indica super hybrid restorer line Huazhan and the widely planted japonica rice variety Xiushui 134, laying a foundation for the broad application of this achievement.
Furthermore, to obtain novel germplasm with high Fd1 expression and free of transgenic components, the team employed a promoter saturation tiling editing strategy and screened new thermotolerant and yield-stable germplasm with high Fd1 expression. This work provides deployable germplasm resources and a constructive strategy for thermotolerant rice breeding, which is of great significance for stabilizing rice yield under heat stress and promoting molecular breeding for rice thermotolerance.
This work was supported by the National Natural Science Foundation of China, National Key Research and Development Program of China, Hainan Province Key Research and Development Program, Biological Breeding-National Science and Technology Major Project, The Innovation Platform for Academicians of Hainan Province, The Agricultural science and Technology Innovation Program, and Academician Workstation of National Nanfan Research Institute (Sanya), CAAS, The support from Ministry of Agriculture and Rural Affairs of the People's Republic of China.
The gene-editing strategy employed in this study was implemented with valuable assistance from Chun Wang at the China National Rice Research Institute, and Yong Zhang and Xu Tang at Southwest University. Key guidance and support were provided by Kejian Wang, Guanfu Fu, Yuexing Wang, Jian Zhang, Yijian Mao, and Baohua Feng from the China National Rice Research Institute; Xiong Yao and Xiaoyan Yang from Chongqing Academy of Agricultural Sciences; Yidan Ouyang from Huazhong Agricultural University; Nan Wang from Southwest University; and Lixin Zhang and Xiumei Xu from Henan University.
Science Bulletin