Black spot is a major foliar disease of sweet basil (Ocimum basilicum) present in a typical cultivation area of northern Italy, including the Liguria and southern Piedmont regions, where this aromatic herb is an economically important crop. In this study, 15 Colletotrichum isolates obtained from sweet basil plants with symptoms of black spot sampled in this area were characterized morphologically and by nuclear DNA analysis using internal transcribed spacers (ITS) and intervening 5.8S nrDNA as well as part of the β-tubulin gene (TUB2) regions as barcode markers. Analysis revealed all but one isolate belonged to the recently described species C. ocimi of the C. destructivum species complex. Only one isolate was identified as C. destructivum sensu stricto (s.s.). In pathogenicity tests on sweet basil, both C. ocimi and C. destructivum s.s. isolates incited typical symptoms of black spot, showing that although C. ocimi prevails in this basil production area, it is not the sole causal agent of black spot in northern Italy. While no other hosts of C. ocimi are known worldwide, the close related species C. destructivum has a broad host range, suggesting a speciation process of C. ocimi within this species complex driven by adaptation to the host.

中文翻译：

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与意大利北部甜罗勒（Ocimum basilicum）的黑点相关的炭疽菌（Colletotrichum ocimi）种群的特征。

黑斑是甜罗勒（Ocimum basilicum）的一种主要叶面病，存在于意大利北部的典型种植区，包括利古里亚和皮埃蒙特南部，在该地区这种芳香草药在经济上很重要。在这项研究中，对15个从甜罗勒属植物中分离出的黑点症状的炭疽菌分离株进行了形态学表征，并使用内部转录间隔区（ITS）以及插入的5.8S nrDNA和部分β-微管蛋白通过核DNA分析。基因（TUB2）区域作为条形码标记。分析显示除一个分离株外，所有分离株均属于最近描述的毁灭梭菌物种复合体的oci。Cocici。只有一个隔离株被鉴定为C. destructivum sensustricto（ss）。在甜罗勒的致病性测试中，C。ocimi和C. destructivum ss分离物均诱发了典型的黑点症状，表明尽管C. ocimi在该罗勒产区盛行，但它并不是意大利北部黑点的唯一病因。 。尽管全世界尚无其他隐孢子虫宿主，但近缘种C. destructivum具有广泛的宿主范围，这表明该隐孢子虫在该物种复合物中的形成过程是由对宿主的适应性驱动的。