Xie Hongwei, Peng Xiaojue, Qian Mingjuan, Cai Yicong, Ding Xia, Chen Qiusheng, Cai Qiying, Zhu Youlin, Yan Longan, Cai Yaohui
Jiangxi Super-rice Research and Development Center, Jiangxi Academy of Agricultural Sciences, National Engineering Laboratory for Rice, Nanchang, China.
School of Life Sciences and Institute of Life Science, Nanchang University, Nanchang, China.
Plant J. 2018 Jun 7. doi: 10.1111/tpj.13982.
D1-cytoplasmic male sterility (CMS) rice is a sporophytic cytoplasmic male-sterile rice developed from Dongxiang wild rice that exhibits a no-pollen-grain phenotype. A mitochondrial chimeric gene (orf182) was detected by mitochondrial genome sequencing and a comparative analysis. Orf182 is composed of three recombinant fragments, the largest of which is homologous to Sorghum bicolor mitochondrial sequences. In addition, orf182 was found only in wild rice species collected from China. Northern blot analysis showed that orf182 transcripts were affected by Rf genes in the isocytoplasmic restorer line DR7. Western blot analysis showed that the ORF182 product was localized in the mitochondria of the CMS line. An expression cassette containing orf182 fused to a mitochondrial transit peptide induced the maintainer line of male sterility, which lacked pollen grains in the anthers. Furthermore, the in vivo expression of orf182 also inhibited the growth of Escherichia coli, with lower respiration rate, excess accumulation of reactive oxygen species and decreased ATP levels. We conclude that the mitochondrial chimeric gene orf182 possesses a unique structure and origin differing from other identified mitochondrial CMS genes, and this gene is connected to non-pollen type of sporophytic male sterility in D1-CMS rice.
D1型细胞质雄性不育（CMS）水稻是一种从东乡野生稻培育而来的孢子体细胞质雄性不育水稻，表现为无花粉粒表型。通过线粒体基因组测序和比较分析检测到一个线粒体嵌合基因（orf182）。Orf182由三个重组片段组成，其中最大的片段与高粱线粒体序列同源。此外，orf182仅在中国收集的野生稻种中发现。Northern杂交分析表明，orf182转录本受同质恢复系DR7中Rf基因的影响。Western杂交分析表明，ORF182产物定位于CMS系的线粒体中。一个含有与线粒体转运肽融合的orf182的表达盒诱导了雄性不育保持系，其花药中缺乏花粉粒。此外，orf182的体内表达也抑制了大肠杆菌的生长，导致呼吸速率降低、活性氧过量积累和ATP水平下降。我们得出结论，线粒体嵌合基因orf182具有与其他已鉴定的线粒体CMS基因不同的独特结构和起源，并且该基因与D1-CMS水稻中非花粉型的孢子体雄性不育相关。
