TFL1/CEN-like genes control intercalary meristem activity and phase transition in rice

Members in the TERMINAL FLOWER 1 (TFL1)/CENTRORADIALIS (CEN) gene family play important roles in controlling inflorescence architecture and phase transition in several different plant species. To investigate the biological functions of TFL1/CEN homologs in rice, we isolated and analyzed four rice TFL1/CEN-like genes, Oscen1-4. We showed that these genes have weak basal expression throughout rice development, and most have distinct expression patterns mainly in the secondary meristems as revealed by mRNA in situ hybridization analyses. The 35S::Oscen1 and 35S::Oscen2 transgenic rice plants exhibit increased numbers of internodes, shortened length and altered radial patterns in the elongated internodes, as well as delayed heading and abnormal panicle architecture. These findings suggest that the TFL1/CEN-like genes in rice play distinct roles in regulating the development of basic structures by stimulating the activities of secondary meristems in the uppermost phytomers.