Phytopathology. 2002 Jun;92(6):617-23. doi: 10.1094/PHYTO.2002.92.6.617.
ABSTRACT The effects of host genotype mixtures on disease progression and pathogen evolution are not well understood in pathosystems that vary quantitatively for resistance and pathogenicity. We used four mixtures of moderately resistant and susceptible winter wheat cultivars naturally inoculated with Mycosphaerella graminicola to investigate impacts on disease progression in the field, and effects on pathogenicity as assayed by testing isolate populations sampled from the field on greenhousegrown seedlings. Over 3 years, there was a correspondence between the mixtures' disease response and the pathogenicity of isolates sampled from them. In 1998, with a severe epidemic, mixtures were 9.4% less diseased than were their component pure stands (P = 0.0045), and pathogen populations from mixtures caused 27% less disease (P = 0.085) in greenhouse assays than did populations from component pure stands. In 1999, the epidemic was mild, mixtures did not reduce disease severity (P = 0.39), and pathogen populations from mixtures and pure stands did not differ in pathogenicity (P = 0.42). In 2000, epidemic intensity was intermediate, mixture plots were 15.2% more diseased than the mean of component pure stands (P = 0.053), and populations from two of four mixtures were 152 and 156% more pathogenic than the mean of populations from component pure stands (P = 0.043 and 0.059, respectively). Mixture yields were on average 2.4 and 6.2% higher than mean component pure-stand yields in 1999 and 2000, respectively, but the differences were not statistically significant. The ability of mixtures challenged with M. graminicola to suppress disease appears to be inconsistent. In this system, host genotype mixtures evidently do not consistently confer either fitness benefits or liabilities on pathogen populations.
摘要 在抗性和致病性呈定量变化的病理系统中，宿主基因型混合物对疾病进展和病原体进化的影响尚不清楚。我们使用四个中度抗性和易感冬小麦品种的混合物，这些混合物是自然接种禾谷球腔菌的，以研究其对田间疾病进展的影响，以及在温室中对从田间采集的分离种群进行测试的致病性影响。三年来，混合物的疾病反应与从它们中采集的分离物的致病性之间存在对应关系。在 1998 年的严重流行年份，混合物的疾病发病率比其组成的纯系低 9.4%（P = 0.0045），而来自混合物的病原体种群在温室测定中的致病力比来自纯系的种群低 27%（P = 0.085）。在 1999 年，流行程度较轻，混合物没有降低疾病严重程度（P = 0.39），来自混合物和纯系的病原体种群在致病性方面没有差异（P = 0.42）。在 2000 年，流行强度居中，混合物的发病率比组成纯系的平均值高 15.2%（P = 0.053），来自四个混合物中的两个的种群比来自组成纯系的平均值的种群的致病性高 152%和 156%（P = 0.043 和 0.059）。1999 年和 2000 年，混合物的产量平均比组成纯系的平均值高 2.4%和 6.2%，但差异不显著。受到禾谷球腔菌挑战的混合物抑制疾病的能力似乎不一致。在这个系统中，宿主基因型混合物显然没有一致地为病原体种群带来适应性优势或劣势。
