Resistance screening of cabbage to black rot and inheritance pattern analysis

Cabbage (Brassica oleracea var. capitata), a member of the genus Brassica, is a significant economic crop worldwide. Black rot (BR) caused by Xanthomonas campestris pv. campestris (Xcc) severely threatens cabbage yield. Therefore, there is an urgent need to breed resistant varieties. To screen resistant germplasms, 171 cabbage inbred lines were inoculated, of which only three were highly resistant materials, namely, ‘M202’, ‘MY’, and ‘YC280’. The biomass of Xcc in highly resistant ‘MY’ and highly susceptible ‘LY’ cabbage lines at different periods after inoculation revealed that 24–72 h after inoculation was the critical period for bacterial proliferation. Inheritance analysis of ‘MY’, ‘LY’ and their constructed populations (P₁, P₂, F₁, B₁, B₂, and F₂) fit the MX2–ADI–ADI model, suggesting that the genetic control of BR resistance in MY was controlled by two pairs of additive-dominant-superior major genes plus additive-dominant-superior polygenes. The major gene heritabilities of B₁, B₂, and F₂ were 33.52 %, 46.66 %, and 52.78 %, respectively. These results increased the number of resources about the BR resistance of cabbage germplasms, elucidated the critical proliferation period and resistance inheritance of this pathogen, and provided a theoretical basis for the breeding of BR-resistant plants, which could expedite the cabbage breeding process.