Frequent introgression of European cauliflowers in the present day cultivated Indian cauliflowers and role of Indian genotypes in the evolution of tropical cauliflower

Abstract

Adaptation to higher temperature and humidity are typical characteristics of Indian cauliflower. The typical Indian cauliflowers have been used worldwide in developing cultivars with tolerance to higher temperature. Present day cultivated types of Indian cauliflowers posses other desirable traits like white and compact curd with semi-erect plant types like the European snowball types. However, there is no molecular-genetic study to define the role of present day European types in the evolution of Indian cauliflowers. We have studied forty five genotypes of cauliflowers including present day cultivars from different maturity groups of Indian cauliflowers and snowball types cultivated in India. To understand the relationship among the different cauliflowers we studied the pattern of diversity using 115 SSRs uniformly distributed throughout the Brassica oleracea genomes along with fourteen important agronomic traits of cauliflowers. It was found that the first two groups of Indian cauliflowers (Group-I and II) were completely different from the snowball types cultivated in India. They are probably originated from the Cornish types. However, the widely cultivated genotypes have undergone several cycles of selection to acquire the desirable plant types. All genotypes of snowball types were clustered together along with genotypes from European origin. The last group of Indian cauliflowers share similarity with snowball types and other European genotypes both in molecular and agronomic level. The genotypes from Taiwan and China were more similar to the Indian cauliflower genotypes which establishes the role of Indian cauliflowers in evolution of different tropical cauliflowers cultivated in different countries. Population structure analysis revealed most likely value of K = 4. Our study establishes the frequent introgression of snowball types in the evolution of Indian cauliflowers with requirement of comparatively lower temperature. The role of the Indian cauliflowers with high temperature tolerance in the evolution of present day tropical cauliflowers is also established.