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，尤其是锈菌（Pucciniales），以其兼具有性与无性繁殖阶段的复杂生活史而闻名。针对无性繁殖对种群遗传多样性的影响，本研究以落叶松-杨栅锈菌（Melampsora larici-populina）为研究对象，采用嵌套分层抽样方案开展相关实验。该方案设置四层分层抽样单元：叶片、枝条、植株与样地。在锈病流行初期与末期两个时间节点，对栽培及野生杨树林分进行取样。最终通过10个微卫星标记（microsatellite markers）对共计641株真菌分离物进行遗传分析。
研究结果表明，野生杨树林分中无性繁殖的遗传特征仅在较低层级的抽样单元（叶片与枝条）中可被观测到。本研究观测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，这证实：尽管锈病流行期内仅发生无性繁殖，但随着病程推进，新基因型仍会参与寄主侵染过程。
该遗传分析揭示了流行病程中自侵染与异侵染过程间的平衡机制。从更广泛的视角来看，本研究的遗传分析阐明了种群遗传学方法在解析流行期内病原分离物繁殖过程中无性繁殖占比，以及准确定量植物病原物无性扩散方面的应用价值。