Data from: Comparative genomics of pathogenic and non-pathogenic beetle-vectored fungi in the genus Geosmithia

Geosmithia morbida is an emerging fungal pathogen which serves as a model for examining the evolutionary processes behind pathogenicity because it is one of two known pathogens within a genus of mostly saprophytic, beetle-associated, fungi. This pathogen causes thousand cankers disease in black walnut trees and is vectored into the host via the walnut twig beetle. G. morbida was first detected in western US and currently threatens the timber industry concentrated in eastern US. We sequenced the genomes of G. morbida in a previous study and two non-pathogenic Geosmithia species in this work and compared these species to other fungal pathogens and nonpathogens to identify genes under positive selection in Geosmithia morbida that may be associated with pathogenicity. Geosmithia morbida possesses one of the smallest genomes among the fungal species observed in this study, and one of the smallest fungal pathogen genomes to date. The enzymatic profile in this pathogen is very similar to its non-pathogenic relatives. Our findings indicate that genome reduction or retention of a smaller genome may be an important adaptative force during the evolution of a specialized lifestyle in fungal species that occupy a specific niche, such as beetle vectored tree pathogens. We also present potential genes under selection in G. morbida that could be important for adaptation to a pathogenic lifestyle.

致病柔丝霉（Geosmithia morbida）是一种新兴真菌病原体，可作为探究致病性背后演化机制的模式物种——因其隶属于多数为腐生、与甲虫共生的真菌属，且是该属已知的两种病原体之一。该病原体可引发黑胡桃罹患千疮病，并通过胡桃小蠹（walnut twig beetle）媒介侵染寄主。致病柔丝霉最早于美国西部被检出，目前已对集中分布于美国东部的木材产业构成威胁。本团队在前期研究中完成了致病柔丝霉的基因组测序，并在本研究中对两株非致病性柔丝霉属物种进行了基因组测序；随后将上述物种与其他真菌病原体及非病原体进行比较分析，以鉴定致病柔丝霉中可能与致病性相关的受正向选择作用的基因。致病柔丝霉拥有本研究观测范围内真菌物种中最小的基因组之一，同时也是迄今已知最小的真菌病原体基因组之一。该病原体的酶学特征谱与其非致病性近缘物种高度相似。本研究结果表明，基因组缩减或保留小型基因组，可能是占据特定生态位的真菌物种（如甲虫媒介的树木病原体）演化出特化生活方式过程中的关键适应性驱动力。本研究还鉴定出致病柔丝霉中受选择作用的潜在基因，这些基因或对其适应致病性生活方式具有重要意义。