Genetics of resistance to Mycosphaerella pinodes in Lathyrus sativus

Three Lathyrus sativus accessions were screened for their reaction to Mycosphaerella pinodes infection. Accession ATC 80878 displayed the lowest percentage stem lesion values (%SL) and was significantly more resistant to M. pinodes than ATC 80407 and ATC 80053. Accession ATC 80407 was the most susceptible, displaying the severest disease symptoms. A backcross and an F-2 population were generated using accessions ATC 80878 and ATC 80407 as the resistant and susceptible parents, respectively. The backcross and F-2 progeny segregated in a 3 : 1 and 7 : 9 ratio, respectively, for resistance/susceptibility, using the 99% confidence intervals for the means of the parental controls in each assay to determine the point of discontinuity. The segregation data from both populations fitted a Mendelian segregation model that suggested that resistance in the L. sativus accession ATC 80878 may be controlled by 2 independently segregating genes, operating in a complementary epistatic manner.