Abstract:

In order to identify the clubroot resistance gene in Chinese cabbage cultivar CCR12049 and develop molecular markers, the following materials were employed: CCR12049, a high-generation inbred line with high resistance to clubroot disease, CM12081, a high-generation inbred line with high susceptibility to clubroot disease, F₁ generation resulting from the cross between CCR12049 and CM12081, and the F₂ generation segregating populations created through selfing of the F₁ generation. Through artificial inoculation identification, polyacrylamide gel electrophoresis, and sequence alignment, it was demonstrated that the disease resistance in tested materials was governed by a dominant single gene. 36 primer pairs were initially tested on both the parental lines and F₁ generation, 4 primer pairs exhibiting polymorphism were identified. Subsequent validation in the F₂ generation revealed that only one pair (cr-26) yielded amplification results consistent with the observed phenotype in the F₂ generation. Through sequencing comparison of the PCR products obtained from the two parental lines and F₁, it was observed that the sequences of the resistant parents and F₁ were identical within the range of 95 bp to 111 bp. Conversely, in the susceptible materials, a deletion of 17 bases (TCTCTATCTCTTACGCA) was identified. These findings suggest that the resistance observed in the impermeable materials may be attributed to the insertion of these 17 bases. This marker has the capability to distinguish the resistant materials and can serve as an SSR marker for the initial screening of clubroot resistance in Chinese cabbage.

Key words: Chinese cabbage, clubroot disease, simple sequence repeats (SSR) molecular marker, inheritance law, sequence alignment