Candidate gene analysis distinguishes regulatory mechanisms for phenological transitions in Indian and Snowball cauliflower

The present study analysed expression of 13 candidate genes in relation to different developmental transitions (vegetative–curding–flowering) in Indian and snowball cauliflwer using quantitative real-time PCR (qRT-PCR). Expression levels of FRUITFULL-c (BoFUL-c), FLOWERING LOCUS T (BoFT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), and LEAFY(BoFLY) increased from seedling to full curd stages in all varieties. VERNALIZATION2 (BoVRN2) and APETALA2 (BoAP2) genes showed a contrasting trend in Pusa Meghna (Indian type) and Pusa Snowball Kt-25 (Snowball type). High expression of BoVRN3, BoVIN2, and BoAP2 in Pusa Snowball Kt-25 fitted well with its vernalisation requirement. The increasing expression of BoFT, SOC1, and BoVIN3 while decreasing trend in BoLFY, REPRODUCTIVE MERISTEM (BoREM1), CAULIFLOWER (BoCAL), and BoFUL-d during seedling–curd initiation–full curd stages in Pusa Shukti (mid-late) matches with Pusa Snowball Kt-25, highlighting their genetic closeness. Hierarchical clustering of these 13 candidate genes grouped all the genes into two major clusters: one had the CAULIFLOWER CURD EXPRESSION 1 (CCE1), BoLFY, BoREM1, BoFUL-c, BoFUL-d, LEAFY Homologous (BoFH), and BoCAL genes while the rest of the genes constituted a second cluster. A significant interaction effect was observed in four candidate varieties and two growing situations (i.e. normal and lower temperature range) for curding-related phenological traits. The information will be helpful in understanding the curding behaviour.