Phytopathology. 1999 Jun;89(6):518-21. doi: 10.1094/PHYTO.1999.89.6.518.
ABSTRACT The common wheat cultivar Thatcher and the backcross derivative Canthatch are moderately or fully susceptible to several races of stem rust because of a suppressor on chromosome 7DL that inhibits the expression of the relevant resistance gene(s). The incorporation of leaf rust resistance gene Lr34 into 'Thatcher' is known to enhance stem rust resistance. The effect of this gene in a 'Canthatch' background and its relationship with the 7DL suppressor were determined by replacing chromosome 7D of 'Canthatch' with 7D of 'Chinese Spring', which possesses Lr34 on the short arm. 'Canthatch' nullisomic 7D was crossed with 'Chinese Spring', followed by a succession of backcrosses to the nullisomic recurrent parent. Homozygous resistant disomic and monosomic substitution lines were recovered that exhibited the same resistant reaction as that of 'Thatcher' possessing Lr34 and as that of 'Canthatch' nullisomic 7D, in which the 7DL suppressor is absent. The results indicate that, in 'Canthatch', Lr34 permits expression of resistance genes normally inhibited by the 7DL suppressor. Furthermore, it is likely that, in 'Thatcher' and 'Thatcher' back-cross derivatives, Lr34 inactivates the 7DL suppressor.
普通小麦品种 Thatcher 和其回交衍生品种 Canthatch 由于 7DL 染色体上的一个抑制子抑制了相关抗性基因的表达，因此对几种茎锈病菌株表现出中度或完全易感性。将叶锈病抗性基因 Lr34 导入 'Thatcher' 已知可以增强茎锈病抗性。本研究通过用携带 Lr34 的短臂 7D 替代 'Canthatch' 的 7D，确定了该基因在 'Canthatch' 背景下的作用及其与 7DL 抑制子的关系。'Canthatch' 缺体 7D 与 'Chinese Spring' 杂交，随后连续回交至缺体亲本。回收了纯合抗性双体和单体替换系，它们表现出与携带 Lr34 的 'Thatcher' 相同的抗性反应，以及缺失 7DL 抑制子的 'Canthatch' 缺体 7D 的抗性反应。结果表明，在 'Canthatch' 中，Lr34 允许通常被 7DL 抑制子抑制的抗性基因表达。此外，在 'Thatcher' 和 'Thatcher' 回交衍生品种中，Lr34 可能使 7DL 抑制子失活。
