Data from: Exploring the role of asexual multiplication in poplar rust epidemics: impact on diversity and genetic structure

Fungal plant pathogens, especially rust fungi (Pucciniales), are well known for their complex life cycles, which include phases of sexual and asexual reproduction. The effect of asexual multiplication on population genetic diversity has been investigated in the poplar rust fungus Melampsora larici-populina using a nested hierarchical sampling scheme. Four hierarchical levels were considered: leaf, twig, tree and site. Both cultivated and wild poplar stands were sampled at two time points at the start and end of rust epidemics. A total of 641 fungal isolates was analyzed using ten microsatellite markers. This study revealed that the genetic signature of asexual multiplication in the wild poplar stand was seen only at lower hierarchical levels (leaf and twig). The observed change in clonal structure, displaying an increase in both gene and genotypic diversity, demonstrates that, despite the fact that only asexual multiplication occurs during the epidemic phase, new genotypes contribute to host infection over time. This genetic analysis provides insights into the balance between auto- and allo-infection processes during the epidemic time course. More generally, this genetic analysis illustrates the utility of population genetics approach for elucidating the proportion of asexual reproduction in the multiplication of isolates during an epidemic, and for proper quantification of asexual dispersal in plant pathogens.

植物病原真菌，尤以锈菌（Pucciniales）为代表，以其兼具有性与无性繁殖阶段的复杂生活史而广为人知。本研究以杨栅锈菌（Melampsora larici-populina）为研究对象，采用嵌套分层抽样方案，探究了无性繁殖对种群遗传多样性的影响。本次研究设置了四层抽样层级：叶片、枝条、单株杨树以及样地。分别在锈病流行期的起始与结束两个时间节点，对人工林与野生林的杨树林分进行了采样。本研究共获取641株真菌分离株，并利用10个微卫星标记（microsatellite markers）开展遗传分析。研究结果显示，野生杨树林分中无性繁殖的遗传信号仅能在较低层级（叶片与枝条）中被检测到。本研究观察到的克隆结构变化（表现为基因多样性与基因型多样性均有所提升）表明：尽管锈病流行阶段仅存在无性繁殖，但随着时间推移，新的基因型仍会参与宿主侵染过程。此项遗传分析揭示了锈病流行进程中自体侵染与异体侵染过程间的动态平衡。从更广泛的意义上来说，本项遗传分析证实了种群遗传学方法的应用价值：其可用于阐明流行期内真菌分离株繁殖过程中无性繁殖所占比例，也可用于精准量化植物病原真菌的无性传播能力。