Distribution of S haplotypes in commercial cultivars of Brassica rapa

Abstract

AbstractSelf‐incompatibility in Brassicaceae plants is sporophytically controlled by a single multi‐allelic locus (S locus), which contains at least three highly polymorphic genes expressed in the stigma (SLG and SRK) and in the pollen (SCR/SP11). Using polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) analysis with SXG‐specific primer pairs, the S haplotypes of F1 hybrid and open‐pollinated commercial cultivars of Brassica rapa were identified. The number of S haplotypes detected in the F1 hybrid cultivars of Chinese cabbage, komatsuna, pak‐choi, turnip, open‐pollinated cultivars of Chinese cabbage and turnip were 9, 9, 4, 11, 13 and 12, respectively. Nine of them had different PCR‐RFLP profiles from those of the S‐tester lines that determined the SLG sequences. Four SLG sequences in the F1 hybrid cultivars were determined and named S53, S54, S55 and S56, respectively. It is demonstrated that the PCR‐RFLP analysis using specific primer pairs of SLG and SRK is useful for identification of the S haplotypes, in both, S homozygous and S heterozygous plants of B. rapa. The possibility of using this method routinely in breeding programmes, and in the evaluation of F1 hybrid seed purity, is discussed.