The alteration in the architecture of a T‐DNA insertion rice mutant osmtd1 is caused by up‐regulation of MicroRNA156f

Plant architecture is an important factor for crop production. Some members of microRNA156 ( miR156 ) and their target genes SQUAMOSA Promoter‐Binding Protein‐Like ( SPL ) were identified to play essential roles in the establishment of plant architecture. However, the roles and regulation of miR156 is not well understood yet. Here, we identified a T‐DNA insertion mutant Osmtd1 ( Oryza sativa multi‐tillering and dwarf mutant). Osmtd1 produced more tillers and displayed short stature phenotype. We determined that the dramatic morphological changes were caused by a single T‐DNA insertion in Osmtd1 . Further analysis revealed that the T‐DNA insertion was located in the gene Os08g34258 encoding a putative inhibitor I family protein. Os08g34258 was knocked out and OsmiR156f was significantly upregulated in Osmtd1 . Overexpression of Os08g34258 in Osmtd1 complemented the defects of the mutant architecture, while overexpression of OsmiR156f in wild‐type rice phenocopied Osmtd1 . We showed that the expression of OsSPL3 , OsSPL12 , and OsSPL14 were significantly downregulated in Osmtd1 or OsmiR156f overexpressed lines, indicating that OsSPL3 , OsSPL12 , and OsSPL14 were possibly direct target genes of OsmiR156f . Our results suggested that OsmiR156f controlled plant architecture by mediating plant stature and tiller outgrowth and may be regulated by an unknown protease inhibitor I family protein.