Abstract: Epidermal hairs are specialized structures on the epidermis of plants that function in crop defense against biotic and abiotic stresses, particularly in warding off herbivores and pests. However, the regulatory mechanism governing epidermal hair formation in rice remains unclear. Here, we report that OsSCR1 (SCARECROW1) and OsSCR2 redundantly promote development of three types of rice trichomes (macro hairs, micro hairs, and glandular hairs), as shown through the reduced and increased trichomes in their knockout and overexpression lines. We demonstrate that OsSCR1 acts upstream of OsWOX3B (WUSCHEL-RELATED HOMEOBOX 3B) in that overexpression of OsWOX3B could rescue the macro hair development defects in osscr1 osscr2 double mutants, and that OsSCR1 protein activates OsWOX3B expression using luciferase activity and chromatin immunoprecipitation quantitative PCR (ChIP-qPCR) assays. In addition, OsSPL10 (SQUAMOSA PROMOTER BINDING PROTEIN-LIKE10) acts upstream of OsSCR1 and enhances its expression to promote the development of macro and micro hairs. Additionally, increasing leaf trichome density through overexpressing OsSCR2 could enhance seedling resistance to locust feeding. Collectively, our findings indicate that OsSPL10 facilitates the process of OsSCR1 inducing OsWOX3B activity to promote the formation of macro and micro hairs in rice.

Key words: epidermal hair, locust feeding, OsSCR, OsSPL10, OsWOX3B