White mould or stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is a devastating fungal disease found in major potato cultivation areas worldwide. The aim of this study was to characterize genetic diversity in the S. sclerotiorum population from the main potato producing regions of India by means of morphological (mycelial growth, colony colour, number and distribution pattern of sclerotia) and molecular characteristics, as well as to evaluate the virulence of S. sclerotiorum isolates in potato for the first time. Among the S. sclerotiorum population analyzed, high phenotypic and genotypic diversity were observed. Using all the morphological characteristics, a dendrogram was constructed based on Gower's similarity coefficient that distributed all the isolates into three clusters at the 0.62 similarity coefficient. Carpogenic germination of apothecia revealed that larger sclerotia produced a greater number of apothecia while smaller sclerotia produced fewer apothecia. Pathogenicity test results revealed that out of 25 isolates, seven were highly aggressive, 14 were moderate and four had low aggressiveness, whilst isolates from Punjab were more pathogenic than those of Uttar Pradesh. Phylogenetic analysis of universal rice primer polymorphism showed high genetic variability within the isolates that grouped all the isolates in three evolutionary lineages in the resulting dendrogram and showed partial relationship with geographical locations of the isolates. Further, the findings suggest the occurrence of higher heterogeneity and genetic diversity among the S. sclerotiorum isolates that indicates the existence of both clonal and sexual reproduction in the pathogen population of potato producing areas in India.

中文翻译：

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基于感染马铃薯（Solanum tuberosum L.）的核盘菌种群的形态病理学和分子变异性的遗传多样性研究

由 Sclerotinia sclerotiorum (Lib.) de Bary 引起的白霉病或茎腐病是一种在全球主要马铃薯种植区发现的毁灭性真菌病害。本研究的目的是通过形态学（菌丝生长、菌落颜色、菌核的数量和分布模式）和分子特征来表征印度主要马铃薯产区的核盘菌种群的遗传多样性，以及首次评估了马铃薯中核盘菌分离株的毒力。在分析的核盘菌种群中，观察到高表型和基因型多样性。使用所有形态特征，基于 Gower 相似系数构建树状图，将所有分离株以 0.62 相似系数分为三个簇。菌核的生菌萌发表明，较大的菌核产生更多的菌核，而较小的菌核产生的菌核较少。致病性测试结果显示，在 25 株分离株中，7 株具有高度侵袭性，14 株为中等侵袭性，4 株具有低侵袭性，而旁遮普省的分离株比北方邦的株致病性更强。通用水稻引物多态性的系统发育分析显示分离株内的高遗传变异性，在所得树状图中将所有分离株分为三个进化谱系，并显示出与分离株地理位置的部分关系。此外，研究结果表明 S. 之间存在更高的异质性和遗传多样性。