Understanding the mechanisms involved in pathogen adaptation to quantitative resistance in plants has a key role to play in establishing durable strategies for resistance deployment, especially in perennial crops. The erosion of quantitative resistance has been recently suspected in Cuba and the Dominican Republic for a major fungal pathogen of such a crop: Pseudocercospora fijiensis, causing black leaf streak disease on banana. This study set out to test whether such erosion has resulted from an adaptation of P. fijiensis populations, and to determine whether or not the adaptation is local. Almost 600 P. fijiensis isolates from Cuba and the Dominican Republic were sampled using a paired‐population sampling design on resistant and susceptible banana varieties. A low genetic structure of the P. fijiensis populations was detected in each country using 16 microsatellite markers. Cross‐inoculation experiments using isolates from susceptible and resistant cultivars were carried out, measuring a quantitative trait (the diseased leaf area) related to pathogen fitness on three varieties. A further analysis based on those data suggested the existence of a local pattern of adaptation to resistant cultivars in both of the study countries, due to the existence of specific (or genotype by genotype) host–pathogen interactions. However, neither cost nor benefit effects for adapted populations were found on the widely used “Cavendish” banana group. These results highlight the need to study specific host–pathogen interactions and pathogen adaptation on a wide range of quantitative resistance phenotypes in banana, in order to develop durable strategies for resistance deployment.

中文翻译：

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多年生作物主要病原体对定量宿主抗性的局部适应模式


了解植物中病原体对定量抗性的适应机制对于制定持久的抗性部署策略具有关键作用，特别是在多年生作物中。最近，在古巴和多米尼加共和国，人们怀疑这种作物的一种主要真菌病原体：斐济拟尾孢菌（Pseudocercospora fijiensis ）对数量抗性的侵蚀，导致香蕉黑叶斑病。这项研究旨在测试这种侵蚀是否是由于斐济虾种群的适应造成的，并确定这种适应是否是局部的。采用配对群体抽样设计，对抗性和易感香蕉品种从古巴和多米尼加共和国分离出近 600 个P. fijiensis菌株进行了取样。使用 16 个微卫星标记检测到每个国家P. fijiensis种群的低遗传结构。使用敏感品种和抗性品种的分离株进行交叉接种实验，测量三个品种与病原体适应性相关的数量性状（患病叶面积）。基于这些数据的进一步分析表明，由于存在特定的（或基因型的基因型）宿主-病原体相互作用，这两个研究国家都存在对抗性品种的局部适应模式。然而，在广泛使用的“卡​​文迪什”香蕉群中，没有发现对适应人群的成本和效益影响。这些结果强调需要研究香蕉中各种定量抗性表型的特定宿主-病原体相互作用和病原体适应，以便制定持久的抗性部署策略。