Inheritance of Leaf Rust Resistance in Durum Wheat

Abstract

The inheritance of resistance to leaf rust (Puccinia recondita L. sp. tritici) in durum wheat (Triticum turgidum L.) is poorly understood. Eight leaf rust‐resistant durum cultivars of diverse origin were crossed and backcrossed to a susceptible line, RL6089, to determine the inheritance of resistance and to provide useful information for durum wheat breeders. Seedlings of the F2, F2, and BCF2 generations were tested with Race 15 in the greenhouse. Lines carrying single genes for resistance were developed from the backcrosses and tested with six races of leaf rust: 1, 15, 58, 100, 104, and 161. Diallel crosses among the resistant parents were made and F2 seedlings tested with Race 15 to determine if any of the parents carry genes for resistance in common. The data showed that ‘Stewart 63’ and ‘Medora’ each carry one dominant and one recessive gene, ‘Quilafen’ carries one dominant gene, and ‘Wakooma’, ‘Lloyd’, ‘Pelissier’, and ‘Golden Ball’ each carry a single recessive gene. ‘Vie’ carries a dominant gene and possibly a recessive gene. All of the diallel crosses segregated susceptible plants, indicating that the parents carry different genes for resistance. A comparison of the reaction to the six races of the derived single‐gene lines and near‐isogenic lines of ‘Thatcher’ carrying specific Lr genes revealed that the dominant gene carried by Stewart 63 may be Lr16 and the dominant gene in Quilafen may be Lr17. The seven other genes have probably not been previously identified. Most of the genes should be of value in durum wheat breeding.