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

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.

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.