Present status and future opportunities in onion research: A review

Abstract

Onions (Allium cepa L.) is a biennial crop of the Alliaceae family with edible portion of the bulbs is the enlarged leaf bases and compact stem. A wide range of landraces and cultivars harbouring immense genetic variation for different traits are available, species like Allium cepa, A. fistulosum and A. roylei can be utilized to develop cultivars resistant against different diseases along with desirable agronomic traits. To evaluate the genetic diversity in onion, number of molecular marker systems is available such as RFLP, RAPD, ISSR, SSR, CAPS and SNP but SSR markers have provided the greatest insights into onion diversity. Doubled haploid (DH) production is an alternative strategy for complete homozygosity and phenotypic uniformity to obtain inbred lines in onion along with this hybridization barrier between A. fistulosum and A. cepa can be overcome using A. roylei as a bridging species. Large future opportunities are there in onion research for various aspects like development of resistance varieties and hybrids to biotic and abiotic factors, improved quality standards, CMS hybrids, DH production etc.