INHERITANCE OF ADULT-PLANT RESISTANCE TO LEAF RUST IN 6 DURUM-WHEAT CULTIVARS

Leaf rust [Puccinia recondita Rob. ex Desm. f. sp. tritici D.M. Henderson] was widespread in Canada and the USA in 1986 and some Canadian cultivars were less resistant than expected. Studies on the inheritance of leaf rust resistance were begun to provide information of use to durum wheat breeders. The inheritance of adult plant resistance to race 15 of leaf rust was investigated in six durum wheat (Triticum turgidum L. var. durum) cultivars, Lloyd, Medora, Pelissier, Quilafen, Stewart 63, and Wakooma, which had been previously shown to carry genes for seedling resistance. Each cultivar had been crossed and backcrossed to a susceptible line, RL6089. Four of the F2 populations and 29 or 30 F2 families from each of the six backcrosses were tested with race 15 in a field nursery. The results were compared with those for the same material tested at the seedling stage in a greenhouse. The combined data showed that each of the genes for seedling resistance was effective at the adult plant stage in the field. The segregation of the BC1F2 progenies indicated that Lloyd carries a dominant gene and Pelissier a recessive gene, that are effective only in adult plants. Thus, all of the seedling resistance genes are of potential value to durum wheat breeders and Lloyd and Pelissier carry additional genes for adult plant resistance that should also be useful.