Abstract: A set of trisomics of Chinese cabbage was used for determining the n+1 gamete transmission rate and locating the gene controlling 2n gamete formation on corresponding chromosome. The results showed that the transmission rates of extra chromosome in different trisomics varied from 0% to 15.38% by male gametes and from 0% to 17.39% by female gametes. Of the 9 F2 populations derived from the hybridizations between each trisomic and Bp058 (2n gamete material), only Tri-4×Bp058 showed that the segregation ratio of plants without 2n gamete formation to plants with 2n gamete formation was 10.38 :1, which fitted the expected segregation ratio of the trisomics (AAa) based on the 7.37% of n+1 gamete transmission through female and 5.88% through male. And in other populations the segregation ratios varied from 2.48:1 to 3.72:1, which fitted the expected 3: 1 segregation ratio of the bisomics (Aa). These results suggested the gene controlling 2n gamete formation in Chinese cabbage Bp058 was located on the chromosome 4. Further trisomic analysis based on the chromosome segregation and the incomplete stochastic chromatid segregation indicated that the gene locus was tightly linked to the centromere.

Key words: Chinese cabbage, gene location, n+1 gamete transmission, primary trisomics, 2n gametes.