The Functional Analysis Of OsTDF1 Reveals The Conserved Genetic Pathway For Tapetum Development Between Rice And Arabidopsis

Anther is the male reproductive organs of plants which is the place for pollen development. The study of anther and pollen development has important theoretical significance. Because male sterility of plant is widely used to improve hybrid seed production, the study has also the value of application. During anther development, the tapetum provides materials for pollen wall formation and nutrition for pollen development. In Arabidopsis, several transcription factors have been identified to form a genetic pathway(DYT1-TDF1-AMS-MS188-MS1) for tapetal development and functions. TDF is a member of R2R3 MYB family essential for early tapetum development in Arabidopsis. Here, we report the characterization of the orthologue of Arabidopsis TDF1 in rice, OsTDF1(Os3g18480). OsTDF1 shares 42% and 69% amino acid sequence identity with TDF1 and its putative MYB domain in the N-terminal region. RT-PCR and in situ hybridization analysis shows OsTDF1 is high specifically expressed in tapetal cells of rice anther. The expression of OsTDF1 in tdf1 can restore its fertility suggesting that it can fulfill the normal function of TDF1 in Arabidopsis. The ostdf1 knockout mutant exhibits male sterile phenotype. Its tapetal cell exhibit vacuolated and hypertrophic phenotype which is similar with that in Arabidopsis tdf1. TUNEL assay showed that the PCD progress is defective in tapetal development. These results showed that OsTDF1 acts as an essential regulator for early tapetal devleopment. The quantitive RT-PCR analysis revealed OsTDF1 acts downstream of UDT1 and upstream of TDR, EAT1, OsMYB103 and PTC1 in the rice tapetal development, suggested that the tapetal genetic pathway is generally conserved between rice and Arabidopsis.