An elite germplasm of <i>Brassica</i> leaf vegetable created by distant hybridisation of ‘Huangxinwu’ and ‘Big Yellow Flower Kale’

ABSTRACT In this study, distant hybridisation was successfully conducted between Brassica rapa var. rosularis Tsen et Lee ‘Huangxinwu’ (2n = 20, AA) and B. oleracea var. alboglabra Bailey ‘Big Yellow Flower Kale’ (2n = 18, CC). A total of three hybrids were obtained through artificial hybridisation and ovary culture. Forty asexual seedlings were obtained by propagation, and thirty were doubled. The identifications of morphological analysis, cytological observation, and SSR molecular analysis showed that one strain was a true hybrid. Allotetraploid hybrids exhibited generally an intermediate phenotype between their parents. The wrinkled leaf surface and leaf colour were more inclined toward the maternal parent, while its leaf thickness and size were more inclined toward the paternal parent. Furthermore, the allotetraploid hybrids showed obvious over‐parent heterosis in biomass and nutritional quality characteristics, including plant weight, soluble sugar, VC, and cellulose, with corresponding contents of 882.76 g, 2.84%, 107.91 mg/100 g and 1.27%. Moreover, the soluble solids and soluble protein contents of these hybrids were 5.62% and 2.56 g/100 g, respectively, which were similar to those of the high‐value parent. In general, the newly synthesised allotetraploid is an innovative germplasm of Brassica vegetables that can be used for future heterosis utilisation and nutritional quality improvement.