Identification of gamyb-4 and Analysis of the Regulatory Role of GAMYB in Rice Anther Development

In higher plants, male reproductive development is a complex biological process that includes cell division and differentiation, cell to cell communication etc., while the mechanism underlying plant male reproductive development remains less understood. GAMYB encodes a gibberellins acid （GA） inducible transcription factor that is required for the early anther development in rice （Oryza sativa L.）. Here, we report the isolation and characterization of a new allele gamyb-4 with a C base deletion in the second exon （-I-2308）, causing a frame shift and premature translational termination. Histological analysis showed that gamyb-4 developed abnormal enlarged tapetum and could not undergo normal meiosis. To understand the regulatory role of GAMYB, we carried out quantitative reverse transcription-polymerase chain reaction analysis and comparison of microarray data. These results revealed that the expression of TDR （TAPETUM DEGENERATION RETARDATION）, a tapetal cell death regulator, was downregulated in gamyb-4 and udtl （undeveloped tapetuml）. While the GAMYB expression was not obviously changed in tdr and udtl-1, and no apparent expression fold change of UDT1 in tdr and gamyb-4, suggesting that TDR may act downstream of GAMYB and UDT1, and GAMYB and UDT1 work in parallel to regulate rice early anther development. This work is helpful in understanding the regulatory network in rice anther development.