Abstract Twenty three fungal endophytes isolated from desi cotton (Gossypium arboreum) were evaluated against two important pathogens of cotton Corynespora cassiicola and Fusarium solani, causal agents of leaf spot and seedling rot respectively. The internal transcribed spacer (ITS) region analysis was used for species-level identification of the fungal endophytes, wherein Curvularia (11) genus followed by Nigrospora (4) was found dominant whereas, Alternaria sp. (2) and Setosphaeria rostrata (2) were other prominent endophytes. Two isolates of Nigrospora sphaerica (CEL 5 and CEL 19) were highly efficient against C. cassiicola and inhibited mycelial growth up to 49.38% and 46.30%, respectively, whereas another isolate of N. oryzae (CEL 2) was effective against F. solani with inhibition of 43.06%. Besides, N. sphaerica (CEL 19) was found to influence the growth of test pathogens when tested for antibiosis. Through GC/ MS analysis of CEL 19 isolate, four major antimicrobial volatile organic compounds (VOCs), namely 1, 3‑diethyl benzene, 1, 4-diehtyl benzene, m-Ethylacetophenone, and p-cymene-7-ol were identified. The phylogeny tree constructed based on ITS sequences revealed two major branches and the first major branch consisted of most of the isolated fungal endophytes, whereas the second major branch consisted of only Coprinopsis cinerea and Puccinia chunjii. The 23 isolates divided into Ascomycota and Basidiomycota phyla were represented by four classes; Agaricomycetes, Eurotiomycetes, Sordariomycetes and Dothidiomycetes which were distributed into six orders. The majority of endophytes belonged to class Dothidiomycetes, followed by Sordariomycetes. There was no much difference observed between the endophytes and the reference taxa, even though it was a pathogen, indicating that pathogenicity of an organism is always not correlated with its gene sequence. Our findings suggest that N. sphaerica could be used as a potential biocontrol agent and its VOCs also have a role in suppressing the growth of plant pathogens.

中文翻译：

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从德西棉（Gossypium arboreum L.）中分离出的可培养内生真菌的拮抗潜力和系统发育

摘要 对从棉花（Gossypium arboreum）中分离出的23种内生真菌进行了评价，分别针对棉花棒状孢子菌和茄病镰刀菌这两种重要病原体，分别是叶斑病和幼苗腐烂病原。内部转录间隔区 (ITS) 区域分析用于真菌内生菌的物种水平鉴定，其中发现 Curvularia (11) 属，其次是 Nigrospora (4)，而 Alternaria sp。(2) 和 Setosphaeria rostrata (2) 是其他突出的内生菌。球形黑孢菌的两种分离物（CEL 5 和 CEL 19）对 C. cassiicola 非常有效，并分别抑制了高达 49.38% 和 46.30% 的菌丝体生长，而另一种稻瘟病菌分离物（CEL 2）则对 F. solani 有效抑制率为 43.06%。此外，N. 当进行抗生素测试时，发现球形菌 (CEL 19) 会影响测试病原体的生长。通过对 CEL 19 分离物的 GC/MS 分析，鉴定了四种主要的抗菌挥发性有机化合物 (VOC)，即 1, 3-二乙苯、1, 4-二乙基苯、间乙苯乙酮和对伞花烃-7-醇。基于 ITS 序列构建的系统发育树揭示了两个主要分支，第一个主要分支由大部分分离的真菌内生菌组成，而第二个主要分支仅由灰鬼伞和春姬菌组成。分为子囊菌门和担子菌门的23个分离株分为四个类别；伞形菌纲、链状菌纲、散粒菌纲和链球菌纲，分为六个目。大多数内生菌属于链球菌纲，其次是梭菌纲。内生菌和参考分类群之间没有观察到太大差异，即使它是病原体，表明生物的致病性总是与其基因序列无关。我们的研究结果表明，球形球孢菌可用作潜在的生物防治剂，其 VOC 还具有抑制植物病原体生长的作用。