Mating trials and genetic study of virulence in Ascochyta lentis to the lentil cultivar 'Northfield'

Ten isolates of Ascochyta lentis derived from a single conidiospore were crossed with each other in order to induce the teleomorph Didymella lentis. Mature pseudothecia and viable ascospores were produced from crosses between compatible mating types. Isolates AL27 and AL36 were determined to be MAT1-1, and isolates AL4, AL41, and USA4 to be MAT1-2. This study identified isolate RB6 to be MAT1-1, not MAT1-2 as previously reported. The inheritance of virulence in A. lentis to the lentil cultivar Northfield was studied by crossing a Northfield-attacking isolate (AL4) with an avirulent isolate (AL36). The F1 progeny segregated in a 3:1 ratio for high virulence/low virulence, suggesting that virulence of A. lentis to Northfield may be controlled by 2 independently segregating genes, operating in mutual epistasis.