S. sclerotiorum is the causal agent of the white mould disease on common bean crops, one of the most threatening fungal diseases occurring across major bean production regions. Currently, there are no commercial cultivars with high levels of genetic resistance to white mould. The aim of this study was to analyse the population structure of 109 isolates of S. sclerotiorum from six dry bean fields in the main production area of Argentina using nine microsatellite loci. A total of 30 multilocus haplotypes (MLHs) were identified, of which 18 MLHs were unique. The remaining 12 MLHs were constituted by 83% of the isolates, six MLHs of which (composed of 75 isolates) were shared at least between two locations. Population genetic structure analysis and discriminant analysis of principal components (DAPC) identified two genetic clusters (subpopulations). The genetic cluster 1 (GC 1) was composed of 21 isolates and 15 MLHs. Similarly, the genetic cluster 2 (GC 2) was composed of 23 isolates and 15 MLHs. These two genetic clusters were observed in most locations sampled. Low levels of genetic differentiation (Φ_ST = 0.198; P < 0.0001) followed by high levels of gene flow (N_m > 1) between genetic clusters were observed. Linkage disequilibrium analysis showed that one of the two genetic subpopulations was under linkage equilibrium (P > 0.001), which is consistent with recombinant populations. These results suggest the occurrence of both modes of reproductive behaviour, clonal and recombining, compromising the durability of management strategies for white mould disease in common bean cultivars.

核盘菌是常见豆类作物白霉病的病原体，是主要豆类产区发生的最具威胁性的真菌病害之一。目前，没有对白霉病具有高水平遗传抗性的商业栽培品种。本研究的目的是分析 109 株核盘菌的种群结构使用九个微卫星位点从阿根廷主产区的六个干豆田中提取。共鉴定出 30 个多位点单倍型 (MLH)，其中 18 个 MLH 是唯一的。其余 12 个 MLH 由 83% 的分离株组成，其中 6 个 MLH（由 75 个分离株组成）至少在两个位置之间共享。种群遗传结构分析和主成分判别分析 (DAPC) 确定了两个遗传簇（亚种群）。遗传簇 1 (GC 1) 由 21 个分离株和 15 个 MLH 组成。同样，遗传簇 2 (GC 2) 由 23 个分离株和 15 个 MLH 组成。在大多数采样位置都观察到了这两个遗传簇。低水平的遗传分化（Φ _ST  = 0.198；P < 0.0001) 随后 观察到基因簇之间的高水平基因流 ( N _m > 1)。连锁不平衡分析表明，两个遗传亚群之一处于连锁平衡（P  > 0.001），这与重组种群一致。这些结果表明，克隆和重组两种生殖行为模式都发生了，这损害了普通豆类品种白霉病管理策略的持久性。