ABSTRACT

The genus Gaeumannomyces (Magnaporthaceae, Magnaporthales, Sordariomycetes, Ascomycota) includes root-infecting pathogens, saprobes, and endophytes. Morphological, biological, and phylogenetic analyses were employed to identify fungal isolates derived from turfgrass roots colonized with ectotrophic, dark runner hyphae. Phylogenetic trees for partial sequences of the 18S nuc rDNA, ITS1-5.8S-ITS2 nuc rDNA internal transcribed spacer, and 28S nuc rDNA regions and of the minichromosome maintenance complex 7 (MCM7), largest subunit of RNA polymerase II (RPB1), and translation elongation factor 1-alpha (TEF1) genes were obtained via maximum likelihood and Bayesian methods. Our isolates consistently formed a distinct and highly supported clade within Gaeumannomyces. Common and distinctive biological and morphological characters reinforced these findings. Additionally, we conducted pathogenicity evaluations and demonstrated the ability of this fungus to colonize roots of ultradwarf bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davey), its native host, via ectotrophic, dark runner hyphae, causing disease symptoms including root discoloration and reduced root and shoot mass. Altogether, our discoveries enabled recognition and description of a new species, Gaeumannomyces nanograminis, associated with rotted roots of ultradwarf bermudagrass.

摘要

Gaeumannomyces属（Magnaporthaceae、Magnaporthales、Sordariomycetes、Ascomycota）包括根感染病原体、腐生菌和内生菌。形态学、生物学和系统发育分析被用来鉴定来自定植了外养型暗转轮菌丝的草坪草根部的真菌分离物。18S nuc rDNA、ITS1-5.8S-ITS2 nuc rDNA 内部转录间隔区和 28S nuc rDNA 区域和微染色体维持复合物 7 ( MCM7 )、RNA 聚合酶 II ( RPB1 ) 的最大亚基的部分序列的系统发育树，以及翻译延伸因子 1-alpha ( TEF1) 基因是通过最大似然和贝叶斯方法获得的。我们的分离株始终在Gaeumannomyces内形成一个独特且高度支持的进化枝。共同和独特的生物学和形态特征加强了这些发现。此外，我们还进行了致病性评估，并证明了这种真菌能够通过外养的暗流道菌丝定植其原生宿主超矮化狗牙根（Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davey）的根部，从而引起疾病症状包括根变色和根和芽质量减少。总而言之，我们的发现使我们能够识别和描述一个新物种Gaeumannomyces nanograminis，与超矮化狗牙根的腐烂根有关。