Submitted to: The Allium Improvement Newsletter
Publication Type: Research notes
Publication Acceptance Date: 4/9/2002
Publication Date: 4/30/2002
Citation: Havey, M.J., Cramer, C.S. 2002. Nuclear resotration of male fertility confirms that a source of onion cytoplasmic male sterility from 'nasik white' is s-cytoplasmic. The Allium Improvement Newsletter. Interpretive Summary:
Technical Abstract: There are two known sources of cytoplasmic-genic male sterility (CMS) used to produce hybrid onion (Allium cepa L.) seed, S and T cytoplasms. Male-sterility has been observed in numerous other onion populations, indicating that additional sources of CMS may exist. A potentially new source of CMS was isolated from the Indian OP population 'Nasik White' and was claimed to be different from S cytoplasm because dominant alleles at the known nuclear male-fertility restoration locus (Ms) for S cytoplasm did not restore male fertility for the 'Nasik White' CMS. We previously demonstrated that 'Nasik White' source of CMS was identical to S cytoplasm for all polymorphisms in the chloroplast and mitochondrial genomes. In this study, we crossed male-sterile 'Nasik White' CMS plants with male-fertile plants known to be homozygous dominant at the Ms locus. For all known 'Nasik White' CMS plants, the testcross progenies were male fertile, demonstrating that the 'Nasik White' souce of CMS is identical to S cytoplasm. As a result, S and T cytoplasms remain the only two sources of CMS naturally existing in and extracted from onion populations.