Overexpression of microRNA408 enhances photosynthesis, growth, and seed yield in diverse plants

• Published in: Journal of integrative plant biology Vol. 60; no. 4; pp. 323 - 340
• Main Authors: Pan, Jiawei, Huang, Dahui, Guo, Zhonglong, Kuang, Zheng, Zhang, He, Xie, Xinyu, Ma, Zengfeng, Gao, Shaopei, Lerdau, Manuel T., Chu, Chengcai, Li, Lei
• Format: Journal Article
• Language: English
• Published: China (Republic : 1949- ) Wiley Subscription Services, Inc 01-04-2018; State Key Laboratory of Protein and Plant Gene Research,Peking-Tsinghua Center for Life Sciences,School of Life Sciences and School of Advanced Agricultural Sciences,Peking University,Beijing 100871,China%Rice Research Institute,Guangxi Academy of Agricultural Sciences,Nanning 530007,China%State Key Laboratory of Plant Genomics and National Center for Plant Gene Research(Beijing),Institute of Genetics and Developmental Biology,Chinese Academy of Sciences,Beijing 100101,China%Department of Environmental Sciences,University of Virginia,Charlottesville,VA 22903,USA
• Subjects: Arabidopsis - genetics; Arabidopsis - growth & development; Carbon dioxide; Carbon dioxide fixation; Chloroplasts - metabolism; Crop yield; Enlargement; Gas exchange; Gene expression; Gene Expression Regulation, Plant; Genes, Plant; Genetic engineering; Grain; Irradiation; MicroRNAs - metabolism; miRNA; Nicotiana - genetics; Oryza; Oryza - genetics; Photosynthesis; Photosynthesis - genetics; Plants (botany); Plants, Genetically Modified; Plastocyanin; Plastocyanin - metabolism; Radiation; RNA, Messenger - genetics; RNA, Messenger - metabolism; Seeds - genetics; Seeds - growth & development; Spectroscopy; Tobacco; Transcription; Transgenic plants
• ISSN: 1672-9072; 1744-7909
• DOI: 10.1111/jipb.12634

The ability of a plant to produce grain, fruit, or forage depends ultimately on photosynthesis. There have been few attempts, however, to study microRNAs, which are a class of endogenous small RNAs post‐transcriptionally programming gene expression, in relation to photosynthetic traits. We focused on miR408, one of the most conserved plant miRNAs, and overexpressed it in parallel in Arabidopsis, tobacco, and rice. The transgenic plants all exhibited increased copper content in the chloroplast, elevated abundance of plastocyanin, and an induction of photosynthetic genes. By means of gas exchange and optical spectroscopy analyses, we showed that higher expression of miR408 leads to enhanced photosynthesis through improving efficiency of irradiation utilization and the capacity for carbon dioxide fixation. Consequently, miR408 hyper‐accumulating plants exhibited higher rate of vegetative growth. An enlargement of seed size was also observed in all three species overproducing miR408. Moreover, we conducted a 2‐year‐two‐location field trial and observed miR408 overexpression in rice significantly increased yield, which was primarily attributed to an elevation in grain weight. Taken together, these results demonstrate that miR408 is a positive regulator of photosynthesis and that its genetic engineering is a promising route for enhancing photosynthetic performance and yield in diverse plants.
This work shows that a conserved small RNA, miR408, promotes photosynthesis and vegetative growth in diverse plant species. In rice, over expression of miR408 leads to enlarged seed size and increased grain weight without compromising other aspects of plant growth, demonstrating the biotechnological potential of miR408 in crop improvement.