Rice OsIAA6 interacts with OsARF1 and regulates leaf inclination

Leaf inclination, a component of crop architecture, influences photosynthetic efficiency and planting den-sity. Various factors, particularly the phytohormones auxin and brassinosteroids (BRs), function in regu-lating lamina joint bending, and understanding of the genetic control of leaf inclination will help to elucidate the relevant regulatory network. Screening a rice T-DNA insertion population revealed a mutant that was insensitive to auxin and displayed an enlarged leaf angle due to increased cell length on the adaxial side of the lamina joint. Genetic analysis revealed that the increased leaf inclination was caused by T-DNA insertion in the promoter region of OsIAA6, resulting in elevated OsIAA6 expression. Further study showed that OsIAA6 interacts with OsARF1 to suppress auxin signaling and regulates leaf inclina-tion. OsIAA6 mediates the BR effects on lamina joint development, and OsBZR1, the key transcription fac-tor in BR signaling, binds directly to the promoter of OsIAA6 to stimulate its transcription. These results indicate the roles of the OsIAA6-OsARF1 module in regulating rice leaf inclination and suggest the syn-ergistic effects of the phytohormones auxin and BR. (c) 2022 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Leaf inclination, an important component of crop architecture, is regulated by the phytohormones auxin and brassinosteroids. This study reveals the genetic control of leaf inclination and the synergistic effects of auxin and brassinosteroids in rice.