Development of Or-gene-based co-dominant markers and their utilization in marker-assisted breeding for ß-carotene...

β-Carotene biofortified crops are the most effective and sustainable components in food-based approaches to tackle vitamin A deficiencies in public. Orange cauliflower (Or gene) is one such options; however, co-dominant marker(s) are an essential requirement to deal with a semi-dominant Or gene for foreground selection in marker-assisted breeding. Thus, the present study aimed to develop and validate co-dominant marker(s) for the Or gene and deploy them for rapid recovery of homozygous OrOr progenies in three different maturity groups of Indian cauliflower. Consequently, three crosses from the early (PA/PKVA-1_HM), mid-early (DC 325/PKVA-1_HM) and mid-late maturity (DC 244/PKVA-1_HM) groups were advanced to F₂, F_2:3, BC₂F₁ and BC₁F₂. The segregation pattern of these populations demonstrated the impact of a single semi-dominant Or gene on petiole base pigmentation and curd colour at maturity. The homozygous OrOr genotype was linked to curd deformity. However, these traits were stage-dependent. Two candidate gene markers, namely CFOr-123 and CFOr-346, were designed utilizing the Or-gene BAC sequencing data. These markers were validated in F₂ population and proved useful in distinguishing homozygous and heterozygous individuals in F₂ and BC₁F₂. Carotenoid content was highest in DC 244/ PKVA-1_HM followed by DC 325/ PKVA-1_HM and PA/ PKVA-1_HM. A total of 16 promising homozygous F_2:3 progenies were developed in tropical cauliflower backgrounds coupled with two Or-gene-based co-dominant markers, which are crucial in managing the ß-carotene biofortification programme of cauliflower.