Transgenic expression of an unedited mitochondrial orfB gene product from wild abortive (WA) cytoplasm of rice (Oryza sativa L.) generates male sterility in fertile rice lines

• Published in: Planta 2015-06, Vol.241 (6), p.1463-1479
• Main Authors: Chakraborty, Anirban, Mitra, Joy, Bhattacharyya, Jagannath, Pradhan, Subrata, Sikdar, Narattam, Das, Srirupa, Chakraborty, Saikat, Kumar, Sachin, Lakhanpaul, Suman, Sen, Soumitra K
• Format: Article
• Language: English
• Subjects: adenosinetriphosphatase; Agriculture; ATP; Biomedical and Life Sciences; Cell Nucleus - metabolism; Crop production; crops; Cytoplasm - genetics; cytoplasmic male sterility; dose response; Down-Regulation; Ecology; Electron Transport; Fertility; Fertility - genetics; flowering; Flowers - genetics; Flowers - growth & development; Forestry; gene expression regulation; Gene Expression Regulation, Plant; gene overexpression; genes; Genes, Plant; genetically modified organisms; H+/K+-exchanging ATPase; H-transporting ATP synthase; heterosis; hybrids; Life Sciences; Male sterility; males; messenger RNA; mitochondria; Mitochondria - metabolism; Mitochondrial Proteins - genetics; Mitochondrial Proteins - metabolism; Mitochondrial Proton-Translocating ATPases - metabolism; Original Article; Oryza - genetics; Oryza - physiology; Oryza sativa; Plant Infertility - genetics; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Sciences; Plants, Genetically Modified; Reproductive system; rice; RNA Editing; RNA, Messenger - genetics; RNA, Messenger - metabolism; Seedlings - genetics; self-pollination; Time Factors; Transformation, Genetic; translation (genetics)
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-015-2269-5

MAIN CONCLUSION : Over-expression of the unedited mitochondrial orfB gene product generates male sterility in fertile indica rice lines in a dose-dependent manner. Cytoplasmic male sterility (CMS) and nuclear-controlled fertility restoration are widespread developmental features in plant reproductive systems. In self-pollinated crop plants, these processes often provide useful tools to exploit hybrid vigour. The wild abortive CMS has been employed in the majority of the “three-line” hybrid rice production since 1970s. In the present study, we provide experimental evidence for a positive functional relationship between the 1.1-kb unedited orfB gene transcript, and its translated product in the mitochondria with male sterility. The generation of the 1.1-kb unedited orfB gene transcripts increased during flowering, resulting in low ATP synthase activity in sterile plants. Following insertion of the unedited orfB gene into the genome of male-fertile plants, the plants became male sterile in a dose-dependent manner with concomitant reduction of ATPase activity of F₁F₀-ATP synthase (complex V). Fertility of the transgenic lines and normal activity of ATP synthase were restored by down-regulation of the unedited orfB gene expression through RNAi-mediated silencing. The genetic elements deciphered in this study could further be tested for their use in hybrid rice development.