在细胞质雄性不育植物中，线粒体与细胞核的协调是决定育性的关键。通过酵母单杂交筛选，我们鉴定了一个在大液泡期，不育小孢子中高度表达的转录因子 ZmDREB1.7，并激活了 CMS 基因 orf355在线粒体中的表达。
该基因是 ZmDREB1.7启动子的弱等位基因，由于缺失 UPR 基因的关键序列，部分恢复了玉米 CMS-S 的雄性育性。
ZmDREB1.7的表达在抗霉素 a 治疗后迅速增加，但在 pro 等位基因存在时这种反应减弱。
我们进一步发现，线粒体中 orf355的表达激活了线粒体逆行信号，从而诱导了 ZmDREB1.7的表达。
这些研究结果表明，在雄性不育决定中，核调节因子和线粒体 CMS 基因之间存在正反馈转录调控，为研究植物细胞核-线粒体之间的通讯提供了依据。
Activation of Mitochondrial orf355 Gene Expression by A Nuclear-Encoded DREB Transcription Factor Causes Cytoplasmic Male Sterility in Maize
1State Key Laboratory of Plant Cell and Chromosome Engineering, Innovative Academy of Seed Design, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
2 University of Chinese Academy of Sciences, Beijing 100864, China
3Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Maize Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China
Abstract:
Coordination between mitochondria and nucleus is crucial for fertility determination in cytoplasmic male sterility (CMS) plant. Using yeast one-hybrid screening, we identified a transcription factor ZmDREB1.7 that is highly expressed in sterile microspores at the large vacuole stage and activates CMS gene orf355 expression in mitochondria. Δpro, a weak allele of ZmDREB1.7 promoter due to the loss of key UPR motif, partially restores male fertility of CMS-S maize. ZmDREB1.7 expression increases rapidly in response to antimycin A treatment, but this response is attenuated in the present of Δpro allele. We further show that expression of orf355 in mitochondria activates mitochondrial retrograde signal, which in turn induces ZmDREB1.7 expression. These findings demonstrate a positive feedback transcriptional regulation between nuclear regulator and mitochondrial CMS gene in male sterility determination and provide insight into nucleus-mitochondria communication in plants.
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