Phytopathology. 2006 Mar;96(3):264-73. doi: 10.1094/PHYTO-96-0264.
ABSTRACT Isolates of wheat leaf rust collected from durum and bread wheat cultivars in France during 1999-2002 were analyzed for virulence on 18 Thatcher lines with single genes for leaf rust resistance (Lr genes). Sampling focused on the five most widely grown bread wheat cultivars (two susceptible and three resistant) to allow statistical comparison of diversity indexes between the cultivars. Leaf rust populations from durum and bread wheats were different. The diversity of the bread wheat leaf rust pathotypes, as measured by the Shannon index, ranged from 2.43 to 2.76 over the 4 years. Diversity for wheat leaf rust resistance was limited in the host since we postulated only seven seedling resistance genes in the 35 cultivars most widely grown during 1999-2002. Leaf rust populations were strongly differentiated for virulence within bread wheat cultivars, and diversity was higher on those that were resistant, mainly due to a more even distribution of virulence phenotypes than on susceptible cultivars. The pathogen population on the susceptible cv. Soissons was largely dominated by a single pathotype (073100), whereas all other pathotypes virulent on cv. Soissons either decreased in frequency or remained at a low frequency during the period studied. Several pathotypes including the most complex one were found only on resistant cultivars, even though most of them were virulent on the susceptible cv. Soissons. Specific interactions were necessary, but not always sufficient, to account for pathotype distribution and frequencies on the cultivars, suggesting that selection for virulence to host resistance genes is balanced by other selective forces including selection for aggressiveness.
摘要 1999-2002 年期间，从法国的硬质小麦和面包小麦品种中采集的小麦叶锈菌分离物，针对具有 18 个叶锈病单基因抗性（Lr 基因）的 Thatcher 系进行了毒性分析。采样重点关注五个种植最广泛的面包小麦品种（两个感病和三个抗病），以便在品种间进行多样性指数的统计比较。硬质小麦和面包小麦的叶锈菌种群不同。4 年来，用香农指数衡量的面包小麦叶锈病生理小种的多样性范围为 2.43-2.76。由于我们假设在 1999-2002 年期间种植最广泛的 35 个品种中只有七个幼苗抗性基因，因此小麦叶锈病抗性的多样性在宿主中受到限制。叶锈菌种群在面包小麦品种内的毒性存在强烈分化，并且在抗性品种上的多样性更高，主要是由于毒性表型的分布更加均匀，而不是在感病品种上。在感病品种 Soissons 上的病原菌种群主要由一个单一的生理小种（073100）主导，而在研究期间，所有其他在 cv. Soissons 上有毒性的生理小种要么频率降低，要么保持在低频率。尽管其中大多数在感病品种 Soissons 上有毒性，但仅在抗性品种上发现了包括最复杂的生理小种在内的几种生理小种。特定的相互作用是必要的，但并不总是足以解释品种上的生理小种分布和频率，这表明对宿主抗性基因的毒性选择是由包括侵略性选择在内的其他选择压力平衡的。
