The multiple roles of OsmiR535 in modulating plant height, panicle branching and grain shape.

The miR156/miR529-SPL module acts a vital role in regulating plant growth and development. Though miR535 shows very high sequence identity to miR156 and miR529, it is still unknown whether miR535 could control plant growth and development. In this study, we performed the evolutionary analyses of miR535s in land plants and found that miR535s were less conserved than miR156s during evolution. In rice, miR535 expressed at a very low level during the vegetative growth but highly accumulated in young panicles, which is similar with OsmiR529, but opposite to OsmiR156. Expectedly, OsmiR535 overexpression in rice reduced plant height by decreasing the 1st and 2nd internode length. Furthermore, OsmiR535 overexpression imposed great influence in panicle architecture, such as more but shorter panicles, and fewer primary/secondary panicle branches. Moreover, OsmiR535 overexpression increased the grain length, but did not affect grain width. Through quantitative real-time PCR analyses, we further revealed that OsmiR535 overexpression repressed the expression of OsSPL7/12/16, as well as the OsSPLs downstream panicle related genes, including OsPIN1B, OsDEP1, OsLOG and OsSLR1. Taken together, our findings suggest that OsmiR535 multiply modulates plant height, panicle architecture and grain shape possibly by regulating OsSPLs genes in rice.