title: The bHLH142 Transcription Factor Coordinates with TDR1 to Modulate the Expression of EAT1 and Regulate Pollen Development in Rice.
abstract: Male sterility plays an important role in F1 hybrid seed production. We identified a male-sterile rice (Oryza sativa) mutant with impaired pollen development and a single T-DNA insertion in the transcription factor gene bHLH142. Knockout mutants of bHLH142 exhibited retarded meiosis and defects in tapetal programmed cell death. RT-PCR and in situ hybridization analyses showed that bHLH142 is specifically expressed in the anther, in the tapetum, and in meiocytes during early meiosis. Three basic helix-loop-helix transcription factors, UDT1 (bHLH164), TDR1 (bHLH5), and EAT1/DTD1 (bHLH141) are known to function in rice pollen development. bHLH142 acts downstream of UDT1 and GAMYB but upstream of TDR1 and EAT1 in pollen development. In vivo and in vitro assays demonstrated that bHLH142 and TDR1 proteins interact. Transient promoter assays demonstrated that regulation of the EAT1 promoter requires bHLH142 and TDR1. Consistent with these results, 3D protein structure modeling predicted that bHLH142 and TDR1 form a heterodimer to bind to the EAT1 promoter. EAT1 positively regulates the expression of AP37 and AP25, which induce tapetal programmed cell death. Thus, in this study, we identified bHLH142 as having a pivotal role in tapetal programmed cell death and pollen development.
authors.affiliation: Academia Sinica Biotechnology Center in Southern Taiwan, Tainan 741, Taiwan Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan sweesuak@gate.sinica.edu.tw.
authors.forename: Swee-Suak
authors.initials: SS
authors.lastname: Ko
authors.affiliation: Academia Sinica Biotechnology Center in Southern Taiwan, Tainan 741, Taiwan.
authors.forename: Min-Jeng
authors.initials: MJ
authors.lastname: Li
authors.affiliation: Institute of Bioagricultural Science, National Chiayi University, Chiayi 600, Taiwan.
authors.forename: Maurice
authors.initials: M
authors.lastname: Sun-Ben Ku
authors.affiliation: Institute of Bioagricultural Science, National Chiayi University, Chiayi 600, Taiwan.
authors.forename: Yi-Cheng
authors.initials: YC
authors.lastname: Ho
authors.affiliation: Academia Sinica Biotechnology Center in Southern Taiwan, Tainan 741, Taiwan.
authors.forename: Yi-Jyun
authors.initials: YJ
authors.lastname: Lin
authors.affiliation: Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Ming-Hsing
authors.initials: MH
authors.lastname: Chuang
authors.affiliation: Academia Sinica Biotechnology Center in Southern Taiwan, Tainan 741, Taiwan.
authors.forename: Hong-Xian
authors.initials: HX
authors.lastname: Hsing
authors.affiliation: Academia Sinica Biotechnology Center in Southern Taiwan, Tainan 741, Taiwan.
authors.forename: Yi-Chen
authors.initials: YC
authors.lastname: Lien
authors.affiliation: Academia Sinica Biotechnology Center in Southern Taiwan, Tainan 741, Taiwan.
authors.forename: Hui-Ting
authors.initials: HT
authors.lastname: Yang
authors.affiliation: Academia Sinica Biotechnology Center in Southern Taiwan, Tainan 741, Taiwan.
authors.forename: Hung-Chia
authors.initials: HC
authors.lastname: Chang
authors.affiliation: Academia Sinica Biotechnology Center in Southern Taiwan, Tainan 741, Taiwan Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Ming-Tsair
authors.initials: MT
authors.lastname: Chan