Auxin Transporter OsPIN1b, a Novel Regulator of Leaf Inclination in Rice ( L.)

Leaf inclination is one of the most important components of the ideal architecture, which effects yield gain. Leaf inclination was shown that is mainly regulated by brassinosteroid (BR) and auxin signaling. Here, we reveal a novel regulator of leaf inclination, auxin transporter OsPIN1b. Two CRISPR-Cas9 homozygous mutants, and with smaller leaf inclination compared to the wild-type, (WT/NIP), while overexpression lines, and have opposite phenotype. Further cell biological observation showed that in the adaxial region, has significant bulge compared to WT/NIP and , indicating that the increase in the adaxial cell division results in the enlarging of the leaf inclination in . The OsPIN1b was localized on the plasma membrane, and the free IAA contents in the lamina joint of mutants were significantly increased while they were decreased in lines, suggesting that OsPIN1b might action an auxin transporter such as AtPIN1 to alter IAA content and leaf inclination. Furthermore, the expression was induced by exogenous epibrassinolide (24-eBL) and IAA, and mutants are insensitive to BR or IAA treatment, indicating that the effecting leaf inclination is regulated by . This study contributes a new gene resource for molecular design breeding of rice architecture.