PCR-based rapid identification of Indian onion populations possessing S-cytoplasm for isolation of CMS lines

摘要

As a novel method of identifying S and N cytoplasms in onion, a mitochondrial DNA based marker cytochrome b (cob) was used to cytoplasmically characterize Indian onion populations. The oligonucleotides amplified 414 bp DNA for S-cytotype and 180 bp for N-cytotype in open-pollinated populations, namely, Punjab Naroya, Punjab Selection, Punjab White, PRO-6, PBR-4 and P-266. Out of the 200 seedlings screened in each population, 19 in Punjab Naroya, 15 in Punjab Selection and 5 in Punjab White showed amplification of 414 bp revealing S-cytoplasmic proportion of 9.5, 7.5 and 2.5%, respectively. While PRO-6, PBR-4 and P-266 showed amplification of 180 bp only, indicating the absence of S-cytoplasm. The results suggest that Punjab Naroya, Punjab Selectionand Punjab White can be exploited for development of male sterile (A) and maintainer (B) lines, while PRO-6, PBR-4 and P-266 can be utilized to isolate maintainer and restorer (R) lines. The study establishes a rapid method of cytoplasm identification inonion, which is pre-requisite to developing CMS lines. In contrast to 4-8 years taken by conventional approach used in India, this technique identifies cytoplasm within 15 days of sowing and proves its practical efficacy for future onion F_1 breeding inthe country.