Identification of microRNAs regulating grain filling of rice inferior spikelets in response to moderate soil drying post-anthesis
Zhenning Teng,
Yinke Chen,
Youqing Yuan,
Yaqiong Peng,
Yake Yi,
Huihui Yu,
Zhenxie Yi,
Jianchang Yang,
Yan Peng,
Meijuan Duan,
Jianhua Zhang,
Nenghui Ye
Affiliations
Zhenning Teng
College of Agriculture, Hunan Agricultural University, Changsha 410128, Hunan, China; Hunan Provincial Key Laboratory of Rice Stress Biology, Hunan Agricultural University, Changsha 410128, Hunan, China
Yinke Chen
College of Agriculture, Hunan Agricultural University, Changsha 410128, Hunan, China; Hunan Provincial Key Laboratory of Rice Stress Biology, Hunan Agricultural University, Changsha 410128, Hunan, China
Youqing Yuan
Changjun High School of Changsha, Changsha 410128, Hunan, China
Yaqiong Peng
College of Agriculture, Hunan Agricultural University, Changsha 410128, Hunan, China
Yake Yi
College of Agriculture, Hunan Agricultural University, Changsha 410128, Hunan, China
Huihui Yu
College of Agriculture, Hunan Agricultural University, Changsha 410128, Hunan, China
Zhenxie Yi
College of Agriculture, Hunan Agricultural University, Changsha 410128, Hunan, China
Jianchang Yang
Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou 225009, Jiangsu, China
Yan Peng
College of Agriculture, Hunan Agricultural University, Changsha 410128, Hunan, China
Meijuan Duan
College of Agriculture, Hunan Agricultural University, Changsha 410128, Hunan, China; Hunan Provincial Key Laboratory of Rice Stress Biology, Hunan Agricultural University, Changsha 410128, Hunan, China; Corresponding authors.
Jianhua Zhang
Department of Biology, Hong Kong Baptist University, Kowloon 999077, Hong Kong, China; School of Life Sciences and State Key Laboratory of Agrobiotechnology, the Chinese University of Hong Kong, Shatin 999077, Hong Kong, China; Corresponding authors.
Nenghui Ye
College of Agriculture, Hunan Agricultural University, Changsha 410128, Hunan, China; Hunan Provincial Key Laboratory of Rice Stress Biology, Hunan Agricultural University, Changsha 410128, Hunan, China; Department of Biology, Hong Kong Baptist University, Kowloon 999077, Hong Kong, China; Corresponding authors.
The grain filling of inferior spikelets is much less complete than that of superior spikelets in rice cultivars with large panicles and numerous spikelets and is promoted by moderate soil drying (MD) post-anthesis. A growing body of evidence has shown that microRNAs function in regulating grain development. However, little is known about the mechanism of microRNA control of grain filling of inferior spikelets in response to MD. In this study, grain filling of inferior spikelets was promoted by MD treatment in Nipponbare. Small-RNA profiling at the most active grain-filling stage was conducted in inferior spikelets under control (CK) and MD treatment. Of 521 known and 128 novel miRNAs, 38 known and 9 novel miRNAs were differentially expressed between the CK and MD treatments. Target genes of differentially expressed miRNAs were involved in multiple developmental and signaling pathways associated with catalytic activity, carbohydrate metabolism, and other functions. Both miR1861 and miR397 were upregulated by MD, leading to a decrease in OsSBDCP1 and OsLAC, two negative regulators of SSIIIa activity and BR signaling, respectively. In contrast, miR1432 abundance was reduced by MD, resulting in upregulation of OsACOT and thus an elevated content of both ABA and IAA. These results suggest that both starch synthesis and phytohormone biosynthesis are regulated by differentially expressed miRNAs in inferior spikelets in response to MD treatment. Our results suggest the molecular mechanisms by which miRNAs regulate grain filling in inferior spikelets of rice under moderate soil drying, providing potential application in agriculture to increase rice yields by genetic approaches.
