Molecular Marker Characterization of Cytoplasm and Restorer of Male Sterility (Ms) Locus in Commercially Grown Onions in India

Cytoplasmic-genic male-sterility system has been extensively employed for the production of onion hybrids. Molecular marker assisted characterization of the cytotypes types and genotyping at the restorer-of male-fertility ( Ms) locus is important for accelerated breeding of onion hybrids. Indian onion breeding has focussed more on open pollinated varieties than hybrids. To accelerate the breeding efforts, marker assisted selection plays a pivotal role. The aim of this study was to characterise the breeding lines, varieties, hybrids and exotic accessions for cytotype and Ms locus. Both the cytotype markers, accD and MKFR were able to distinguish cytoplasm. But for initial characterisation, employment of both the markers is advised since accD marker does not distinguish between N and T cytoplasm. Sequence studies proved that N and T cytoplasm are identical. Out of the two Ms locus markers, AcPMS1 was more reliable than AcSKP1. For determination of cytotype, a bulk of 5 plants can be used but Ms locus cannot be determined using bulk strategy. Indian onions have a predominance of normal (N) cytoplasm and homozygous recessive ( msms ) locus which might be beneficial for hybrid development. These findings will assist Indian onion breeders to develop MAS strategies for accelerating hybrid development programme for release of varieties with high productivity and uniformity