Gγ-protein GS3 function downstream of OsmiR396/GS2 module to regulate grain size in rice

Abstract Rice is one of the main crops in the world which provides food for more than one half world population. Grain size is tightly associated with grain weight, one of the three components determining yield in rice. Quite a few grain size determining quantitative trait loci (QTLs) have been identified, and several grain size-regulating signaling pathways been formed. Here, we showed that in the MIM396 plants, expression of GS3 gene was influenced. Through various biochemical assays, we proved that the miR396/GS2 module could directly regulate the Gg-protein GS3 to regulate grain size. Moreover, tight genetic association existed between miR396/GS2 and GS3. Moreover, other G-protein factors might also be connected with miR396/GS2 module, and thus factors from different pathways form a network to regulate grain size. Therefore, elucidation of these crosstalk would not only further our understanding of the molecular mechanism of grain size regulation, but also help guide modern crop breeding.