Lack of vernalization requirement in Chinese kale was due to the deletion of BoFLC as well as low expression of its paralogs

Non-vernalization in Chinese Kale, a vegetable with bolting stem harvested and consumed, is an import agronomic trait. However, the genetic and molecular mechanisms underlying non-vernalization in Chinese Kale remain unclear. To better understand the genetic control of flowering time in Chinese kale, a Chinese kale (a non-vernalization crop) was crossed with a kale (a vernalization crop). In the F2 population, flowering time was analyzed using Bulked Segregant RNA-seq (BSR-seq)34. We showed that the phenotypic segregation of early and late flowering was controlled by several QTLs. Based on the genetic results, we constructed an F2:3 family in which the phenotypic segregation of early flowering and late flowering was controlled by a single major QTL. This major QTL was then cloned using map-based cloning procedures. The causal mutation was identified and the impact of the causal mutation were studied in detail. This study provides insight in our understanding of vernalization. Our results will facilitate studies on the genetic and molecular mechanisms of flowering time in other important Brassica crops, and the identified polymorphic gene can be used in breeding programs of B. oleracea crops.