Venturia inaequalis is a notorious fungal pathogen and show classical gene for gene interaction with its apple host. Neutral markers provide clues about history, evolutionary potential, genetic diversity and population structure of V. inaequalis. The genetic diversity and population structure of fungus indicates that the pathogen is highly diverse with the capacity to breach the scab resistance genes. In the present study, we collected 108 V. inaequalis isolates from three apple cultivars differing in Rvi1 resistance gene. Based on the AMOVA, the variation was mostly distributed among the isolates, providing evidence of non-existence of subpopulation in orchards thus founder population is difficult to arise in Kashmir apple orchards. Pair wise genetic differentiation is less due to regular occurrence of gene flow between the populations residing on different orchard as infected material is transported without stringent quarantine measures. Based on principal coordinate analysis and clustering algorithm as implemented in STRUCTURE, we observed admixture between the two subpopulations, which is quite low, suggesting the existence of pre-zygotic and post-zygotic barriers to gene flow and we cannot rule out the existence of other structures shared by accessions belonging to different varieties. Due to the continuous increase in introduction and monoculture of apple varieties, mixed orchard with different host resistance specificities are more suitable for managing the apple scab in Kashmir valley.

中文翻译：

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克什米尔山谷不同宿主抗性特异性下的半生物营养真菌 Venturia inaequalis 的种群结构

Venturia inaequalis 是一种臭名昭著的真菌病原体，显示出与其苹果宿主基因相互作用的经典基因。中性标记提供了关于 V. inaequalis 的历史、进化潜力、遗传多样性和种群结构的线索。真菌的遗传多样性和种群结构表明，病原体高度多样化，具有破坏抗疮痂病基因的能力。在本研究中，我们从三个不同 Rvi1 抗性基因的苹果栽培品种中收集了 108 个 V. inaequalis 分离株。基于AMOVA，变异主要分布在分离株之间，提供了果园中不存在亚种群的证据，因此在克什米尔苹果园中很难出现始祖种群。由于在没有严格检疫措施的情况下运输受感染材料，因此居住在不同果园的种群之间经常发生基因流动，因此成对遗传分化较少。基于 STRUCTURE 中实现的主坐标分析和聚类算法，我们观察到两个亚群之间的混合非常低，表明存在合子前和合子后基因流动障碍，我们不能排除其他亚群的存在。属于不同品种的种质共有的结构。由于苹果品种引种和单一栽培的不断增加，不同寄主抗性特异性的混合果园更适合管理克什米尔山谷的苹果黑星病。