Identification Of FON Races Of Fusarium Wilt Of Watermelon In Ningxia And Localization Of Resistance Genes In FON Race 2 Of Watermelon

To identify the FON races and the locus of FON race2 disease resistance genes in watermelon,strains of Fusarium oxysporum f.sp.niveum isolated from Ningxia and watermelon germplasm were studied using molecular biology,differential hosts and GWAS methods.The results of the study include that:(1)All 84 isolates obtained from 11 commercial watermelon fields were Fusarium oxysporum,23 of which were Fusarium oxysporum f.sp.niveum.(2)Eight isolates(35%)were identified as FON race 2,three isolates(13%)were identified as FON race 3 and the rest were non-pathogenic strains,FON race 3 is the first report in China.(3)Three published marker sets(Fon-1/Fon-2,FONSIX6,FNR)failed to accurately identify FON races from Ningxia,and the molecular biology methods used to identify FON races are poorly accurate.(4)The highly invasive FON race 2 isolate was found in two fields in Yinchuan and Shizuishan counties in Ningxia.The FON race 3 isolate was co-occurring with the FON race 2 isolate,both occurring in Jinshan Village,Heilan,Yinchuan.(5)Twenty-three strains of Fusarium oxysporum f.sp.niveum obtained from commercial watermelon fields in Ningxia were dominated by FON race 2.(6)Six QTL associated with FON race 2 resistance in watermelon were identified,with four matching previously reported QTL for FON race 2 resistance located on chromosomes 1,5,8 and 11,and two new QTL located on chromosomes 3 and 7 that had not been reported and may be new sources of resistance were identified.