Identification of male sterile (T, S) of fertility (N) cytoplasm by PCR-based molecular markers to access maintainer lines in onion

Purpose: Modern onion breeding is almost completely based on the production of hybrid seed. This project was performed to evaluate the effectiveness of marker-assisted selection (MAS) in identification of the cytoplasmic types and Ms locus in 123 onion accessions. Research method: Three cytoplasmic markers cob, accD and MK were used to identify the sterility (S) from the fertility (N) cytoplasm and four nuclear molecular markers (OPT, PsaO, Jnurf-13 and AcSKP1) were used for genotyping of Ms alleles. Findings: The results showed that the two accD and cob markers were quite similar in the detection of the type of cytoplasm with 100% male sterility for male sterile lines and 100% fertility for maintainer lines. The MK marker was able to distinguish T-type cytoplasm as well. Based on the results, the frequency of fertility (N) was much more than the frequency of sterility (S and T) cytoplasm found to be 90% in Dorche (pop.1), 100% in Dorche (pop.2) and Kashan based on marker cob and accD and with MK marker, was found to be 80%, 90% and 82% in Dorche (pop.1), Dorche (pop.2) and Kashan, respectively. Limitations: In this study, nuclear markers were not successful due to not finding linkage disequilibrium with the Ms locus, suggested more markers to be evaluated. Originality/Value: Molecuar markers were very suitable for the indentification of S or N lines. Cytotype (N/S) determination of plants by usingmolecular markers (cob, accD and MK), could easily reduce the population size required for the production of onion hybrid seeds.