GENETIC ANALYSIS OF FERTILITY RESTORATION SYSTEMS AND CYTOPLASMIC TYPES IN ONION (ALLIUM CEPA) GENOTYPES USING DNA MARKERS

Comparing the yield of open-pollinated varieties (OPVs) and hybrids, signifies the importance of hybrid breeding. Hybrid development in onion relies on cytoplasmic genic male sterility (CGMS) system. But identification and maintenance of cytoplasmic genic male sterile (A) and maintainer (B) lines in biennial crop takes four to eight years through conventional breeding approach. However, DNA marker-based characterization of cytotype and restoration of fertility (Rf) gene reduces the time span to speed up hybrid development process. Present study was designed for morphological and molecular characterization of cytotype and Rf locus. For this purpose, twenty-one onion genotypes were characterized for bulb weight, bulb diameter, number of rings, plant height, and neck diameter during field experimentation. Likewise, four DNA markers i.e., 5Cob marker, OrfA501, orf725MFKR1 and orf725MFKR2 were used for cytotype and three markers i.e., AcSKP1FU, AcSKP1SU and AcPMS1 for Rf locus characterization. Molecular characterization classified genotypes into three groups: group 1 (including Phulkara, White-Pearl, Sultan, Yellow-S3, Desi-Red-S4, MirpurKhas-S3, Nasarpuri-S4, VRIO-02, Desi-Red, VRIO-10, VRI-06, Golden-ORB and T.E.G.) suited for deriving B lines; group 2 (featuring White-Pearl-V, 1122, Sultan-F1, HNO300A and Kessar) with potential for A line derivation; and group 3 (comprising of Hike and Glory) suitable for both A and B line derivation. These findings will help in faster derivation of A and B lines, consequently accelerating onion hybrid development.