Research on the Variation of Populus deltoides×P. cathayana F2 Generation against Alternaria alternata

The study was carried out using three generations,with the F1 produced by interspecific hybridiations between a resistant Populus deltoides female and a susceptible P. cathayana male. F1 inbreeding made the F2 generation. The susceptibility of parents, F1 and F2 to Alternaria alternata was tested both in the nursery and laboratory. The results show that the clones that were scored as being Ⅰ,Ⅱ, and Ⅲ in the nursery were also scored as Ⅰ,Ⅱ, and Ⅲ(Ⅰ: 0,Ⅱ: ≤15%,Ⅲ: 15%) in the laboratory. F2 segregated in a 1:2:1 ratio for the resistance to A. alternata (Fr.) Keissler. The data suggest that the resistance be detemined by a single recessive gene for P. deltoides. The study is the basis for future identifying molecular markers linking to the locus against A. alternata by Bulked Sergeant Analysis (BSA) and molecular markers.