Genetic analysis of leaf trichome density using mixed major gene plus polygene inheritance model in Brassica rapa ssp. chinensis

ABSTRACT Leaf trichome is an important trait for stress‐resistance breeding in Brassica crops, but its scientific evaluation and identification are rarely reported. To investigate the inheritance of leaf trichome in non‐heading Chinese cabbage, two inbred lines, ‘14XS23W’ (glabrous) and ‘14XS23Y’ (hirsute), were used to generate F 1 and F 2 populations for joint analysis using a mixed major genes plus polygene inheritance model. The density of adaxial leaf trichomes was controlled by two pairs of additive‐dominance‐epistasis major genes plus additive‐dominance polygenes. The broad‐sense heritabilities of the major genes were 93.8% and 85.51%, respectively, for greenhouse and open‐field conditions. However, the density of the abaxial leaf trichome was controlled by two pairs of additive‐dominance‐epistasis major genes plus additive dominance‐epistasis polygenes. The broad‐sense heritabilities of the major genes were 91.45% and 72.20%, while the polygenes were 0% and 14.5%, respectively, for greenhouse and open field environments. These results indicated that trichome density in non‐heading Chinese cabbage was primarily controlled by two pairs of major genes with high heritability, implying that this trait is suitable for rapid selection in early generations.