Chinese cabbage clubroot resistance genotyping and evaluation of combining ability

Chinese cabbage is a multivitamin vegetable crop and it is in constant demand due to its taste and dietary qualities, as well as the ability to harvest this crop twice a year due to the short growing season. There are less than 70 cultivars and hybrids in the State Register of Russia, many of them are susceptible to clubroot caused by soil pathogen P.brassicae Wor. In Russia, consumer demand needs to be met with new competitive hybrids that are resistant to major diseases such as clubroot. The aim of the study to evaluate the collection of inbred Chinese cabbage lines with clubroot resistance and to select promising hybrid combinations for further creation of F1 hybrids of the crop.
Field trials were carried out in the summer-autumn period of the year 2021. Twenty five Chinese cabbage inbred lines (B.rapa ssp. pekinensis) and 154 hybrid combinations from crossing these lines were used as plant material. To achieve the goal, the following methods were applied: evaluation of combining ability (GCA and SCA) in the system of crossings of two groups of genotypes; clubroot disease test; molecular genotyping using molecular markers of clubroot resistance genes. As a result of a Chinese cabbage hybrids field trials, 14 were identified that exceed the standards in terms of “mass of head” by at least 20%. Three CR inbred lines K7, K19 and P1d4 with high values of GCA were identified, which are recommended for development of a new hybrid combinations. Based on the data of molecular genotyping of the clubroot resistance genes CRa, CRb, and CRA05 and the disease resistance of Chinese cabbage lines, the genetic collection of lines was differentiated by clubroot resistance genes. This will make it possible to use them as resistance donors when pyramiding resistance genes.

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