Diversity of Colletotrichum species associated with torch ginger anthracnose

Anthracnose caused by Colletotrichum species is one of the most important diseases of torch ginger. The disease leads to loss of aesthetic and commercial value of torch ginger stems. This study aimed to characterize Colletotrichum species associated with torch ginger anthracnose in the production areas of Pernambuco and Ceará. A total of 48 Colletotrichum isolates were identified using molecular techniques. Pathogenicity tests were performed on torch ginger with representative isolates. Phylogenetic analyses based on seven loci—DNA lyase (APN2), intergenic spacer between DNA lyase and the mating-type locus MAT1-2-1 (APN2/MAT-IGS), calmodulin (CAL), intergenic spacer between glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and a hypothetical protein (GAP2-IGS), glutamine synthetase (GS), and β-tubulin (TUB2)—revealed that they belong to five known Colletotrichum species, namely, C. chrysophilum, C. fructicola, C. siamense, C. theobromicola, and C. tropicale, and three newly discovered species, described here as C. atlanticum, C. floscerae, and C. zingibericola. Of these, C. atlanticum was the most dominant. Pathogenicity assays showed that all isolates were pathogenic to torch ginger bracts. All species are reported for the first time associated with torch ginger in Brazil. The present study contributes to the current understanding of the diversity of Colletotrichum species associated with anthracnose on torch ginger and demonstrates the importance of accurate species identification for effective disease management strategies.由炭疽菌属（Colletotrichum）物种引发的炭疽病是火炬姜生产中最为严重的病害之一，该病害会导致火炬姜茎秆的观赏价值与商业价值受损。本研究旨在对巴西伯南布哥州与塞阿拉州主产区中，与火炬姜炭疽病相关的炭疽菌属物种开展物种鉴定与特征解析。研究共收集48株炭疽菌分离物，并借助分子生物学技术完成物种鉴定。选取代表性分离物接种火炬姜以开展致病性测定。基于7个基因位点——DNA裂解酶（APN2）、DNA裂解酶与交配型位点MAT1-2-1之间的基因间区（APN2/MAT-IGS）、钙调蛋白（CAL）、甘油醛-3-磷酸脱氢酶（GAPDH）与假设蛋白之间的基因间区（GAP2-IGS）、谷氨酰胺合成酶（GS）以及β-微管蛋白（TUB2）——开展系统发育分析，结果表明这些分离物隶属于5个已知炭疽菌属物种：金色炭疽菌（C. chrysophilum）、果生炭疽菌（C. fructicola）、暹罗炭疽菌（C. siamense）、可可生炭疽菌（C. theobromicola）与热带炭疽菌（C. tropicale），以及3个本研究首次定名的新物种：大西洋炭疽菌（C. atlanticum）、C. floscerae与姜生炭疽菌（C. zingibericola）。其中大西洋炭疽菌为优势种群。致病性检测结果显示，所有供试分离物均能侵染火炬姜苞片。本研究首次在巴西报道了所有与火炬姜炭疽病相关的上述炭疽菌物种。本研究深化了学界对火炬姜炭疽病相关炭疽菌属物种多样性的认知，并证实了精准物种鉴定对制定高效病害防控策略的重要价值。