Abstract:

In order to excavate the diversity of TuMV resistant genes and make the genetic improvement strategy and measures for the prevention and control in Chinese cabbage，QTL analysis of the dominant locus was conducted in the study，which would be helpful to cultivate the broad-spectrum resistance of Chinese cabbage varieties. The F2 population was constructed from the parents‘89B’（resistant）and‘Qiangshi’（susceptible），which were the highly inbred Chinese cabbage lines. The F2 population individuals were inoculated by TuMV C4 isolate，and the segregation from F2 did not fit the expected segregation for a Mendelian model 3︰1（χ2 = 4.8 > χ0.052 = 3.84），so quantitative trait locus controlled the character，not a single gene. Choosing 40 highly resistant/susceptible individuals from F2 population，respectively，to mix the pools，and the two parents and two pools were re-sequenced. By calculation analysis of △(SNP-index) between parent and pools，two main regions were obtained（A07 chromosome：13.9–14.4 Mb and A08 chromosome：16.4–17.4 Mb）. There were 68 genes in the above two regions，and 6 out of 68 were associated with resistance in plants（Bra028499，Bra028500，Bra016311，Bra016312，Bra016313 and Bra016314）. In addition，Bra028499 and Bra028500 coded the disease-resistant proteins，and Bra016311，Bra016312，Bra016313 and Bra016314 coded TMV-resistant proteins. Bra028499，Bra028500，Bra016311 and Bra016314 contained the TIR-NBS-LRR domains. About 80% of the resistance genes cloned in plants belonged to the NBS gene families，indicating that these genes may be associated with Chinese cabbage resistance to TuMV.

Key words: Chinese cabbage, TuMV, dominant locus, QTL-seq, genetic analysis