Mapping And Cloning Of The Fusarium Resistance Gene In Cabbage (Brassica Oleracea Var. Capitdta)

White cabbage (Brassica oleracea var. capitata) is an important brassica crop. Since2001, cabbageFusarium wilt (CFW) caused by Fusarium oxysporum hit the cabbage growing area in northern China,causing great losses to both yield and quality of cabbages in China.CFW was firstly found in the US and then hit many other countries where cabbages were grown. InChina, CFW was newly discovered and related research has just begun. Currently, the race type of theCFW pathogen in China has never been discovered; the resistance level of the breeding materials has notbeen identified yet and the CFW resistance breeding work is just at a starting stage; molecular markerresearch about CFW resistance is rare, and studies concerning mapping and cloning of the resistance genehave not been reported yet. The study here reported evaluation of the damage situation, identification ofthe pathogen type, mapping and cloning of the resistant gene and cultivation of CFW resistant varieties.The results are as follows:1. Damaged situation evaluation and pathogen type identificationThe damaged situation by CFW in China was evaluated. In a decade, CFW has developed fromBeijing in2001to four other provinces including Hebei, Shanxi, Shaanxi and Gansu in2013. Both thedamaged area and the losses of cabbage production were increased continuously. We further isolatedpathogens from the five provinces. All the isolates were identified to be Fusarium oxysporum f. sp.conglutinans Race1, however, these strains were found to be more virulent.2. Mapping and cloning of the CFW resistance geneInDel markers were developed using the re-sequencing data of the parents from which the DHpopulation was derived. The resistance gene was mapped to a384kb region on chromosome C06usingthe DH population. The F2population derived from the same parents was used to further fine mapping ofthe gene to an84kb region. The candidate gene for resistance to CFW in cabbage was obtained andconfirmed through several ways. The result showed that the candidate gene FOC1belonged to the TIR-NBS-LRR type R gene. The candidate gene was further confirmed by analysis of variation locus of FOC1in80cabbage inbred lines.3. Screening of the resistant materials and cultivation of CFW resistant varietiesEight new inbred lines and11hybrids were identified with high resistance to CFW. Microsporeculture was conducted to obtain a total of196DH lines. Three elite DH lines were selected based on theagronomic traits evaluation and molecular marker assays. Hybrids derived from the three DH lines andother inbred lines were obtained through hand pollination and three of them were identified with bothelite agronomic traits and high resistance to CFW.In summary, the study reported here is of great significance in two aspects:Firstly, in the aspect of application, we evaluated the damage situation of CFW in China, identifiedthe pathogen type, screened for new resistant materials and hybrids and cultivated new resistant hybridsusing microspore culture and marker-assisted selection, which provides the basis for cabbage resistancebreeding as well as for CFW controlling. Secondly, in terms of basic research, we mapped and cloned the resistant gene and validated it using80cabbage inbred lines. This work paves the way for further function and mechanism analysis of theresistance gene.