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 cat-alytic activity,carbohydrate metabolism,and other functions.Both miR1861 and miR397 were upregu-lated 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 syn-thesis and phytohormone biosynthesis are regulated by differentially expressed miRNAs in inferior spi-kelets 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 applica-tion in agriculture to increase rice yields by genetic approaches.

Zhenning Teng;Yinke Chen;Youqing Yuan;Yaqiong Peng;Yake Yi;Huihui Yu;Zhenxie Yi;Jianchang Yang;Yan Peng;Meijuan Duan;Jianhua Zhang;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;Changjun High School of Changsha,Changsha 410128,Hunan,China;Key Laboratory of Crop Genetics and Physiology of Jiangsu Province,Yangzhou University,Yangzhou 225009,Jiangsu,China;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

作物学报（英文版）

[1]Zhenning Teng;Yinke Chen;Youqing Yuan;Yaqiong Peng;Yake Yi;Huihui Yu;Zhenxie Yi;Jianchang Yang;Yan Peng;Meijuan Duan;Jianhua Zhang;Nenghui Ye-.Identification of microRNAs regulating grain filling of rice inferior spikelets in response to moderate soil drying post-anthesis)[J].作物学报（英文版）,2022(04):962-971

miR1861,OsSBDCP1,OsLAC,miR1432,OsACOT,kelets

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