2018-08-08
Abstract
Key message A single recessive gene for complete resistance to powdery mildew and a major-effect QTL for partialresistance to downy mildew were co-localized in a Cucumis hystrix introgression line of cucumber.Abstract Downy mildew (DM) and powdery mildew (PM) are two major foliar diseases in cucumber. DM resistance (DMR)and PM resistance (PMR) may share common components; however, the genetic relationship between them remains unclear.IL52, a Cucumis hystrix introgression line of cucumber which has been reported to possess DMR, was recently identifiedto exhibit PMR as well. In this study, a single recessive gene pm for PMR was mapped to an approximately 468-kb regionon chromosome 5 with 155 recombinant inbred lines (RILs) and 193 F2plants derived from the cross between a susceptible
line ‘changchunmici’ and IL52. Interestingly, pm was co-localized with the major-effect DMR QTL dm5.2 confirmed bycombining linkage analysis and BSA-seq, which was consistent with the observed linkage of DMR and PMR in IL52. Further,phenotype–genotype correlation analysis of DMR and PMR in the RILs indicated that the co-localized locus pm/dm5.2confers complete resistance to PM and partial resistance to DM. Seven candidate genes for DMR were identified withindm5.2 by BSA-seq analysis, of which Csa5M622800.1, Csa5M622830.1 and Csa5M623490.1 were also the same candidategenes for PMR. A single nucleotide polymorphism that is present in the 3ˊ untranslated region (3′UTR) of Csa5M622830.1co-segregated perfectly with PMR. The GATA transcriptional factor gene Csa5M622830.1 may be a likely candidate genefor DMR and PMR. This study has provided a clear evidence for the relationship between DMR and PMR in IL52 and shedsnew light on the potential value of IL52 for cucumber DMR and PMR breeding program.
Link text : https://link.springer.com/article/10.1007%2Fs00122-018-3150-2
