engleski

Identification of QTL associated with hop resistance to Verticillium albo-atrum

Outbreaks of the lethal strain of Verticillium wilt infecting hops cause substantial yield losses and can also render fields out of production for several years. Since chemical control is unavailable or hard to apply in field conditions, breeding hop cultivars with genetic resistance in addition to phytosanitary measures is the only way of controlling the disease. In order to elucidate the genetic control of Verticillium wilt resistance in hops, a pseudotestcross population of 144 plants was derived. The mother plant, cultivar ‘Wye Target’, carries the strongest and predicted genetic resistance while the male breeding line 2/1 is susceptible. Phenotyping of wilting symptoms was performed under control conditions using ten plants for each genotype. A genetic linkage map was constructed using various types of molecular marker but with a high number of codominant SSRs. The genetic linkage map included 203 markers, forming ten major linkage groups of the maternal and paternal maps, covering 552.98 and 441.1 cM, respectively. On a single chromosomal region of LG03 of both parental maps, one significant QTL for Verticillium wilt resistance was detected at LOD 7 for the first time in hop. The QTL accounted for 24.2 to 26.0% of the phenotypic variance. The presented genetic linkage map and identified QTL are an important first step in deciphering the genetic basis of hop Verticillium wilt resistance. This work also opens possibilities of marker development and exploitation in marker assisted selection breeding.

Humulus lupulus; Verticillium wilth; resistance; genetic mapping; pseudotestcross; QTLs; marker-assisted selection

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