Host-to-Pathogen Gene Transfer Facilitated Infection of Insects by a Pathogenic Fungus

PLoS Pathogens

Raymond J. St. Leger¹  Hsiao-Ling Lu¹  Hong Zhao²  Chuan Xu²  Weiguo Fang²  Xiaoxuan Chen² 

[1] Department of Entomology, University of Maryland, College Park, Maryland, United States of America;Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, China

关键词: Insects;    Fungi;    Fungal genetics;    Metarhizium;    Sterols;    Fungal genomics;    Fungal pathogens;    Phylogenetic analysis;   

DOI  :  10.1371/journal.ppat.1004009

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Metarhizium robertsii is a plant root colonizing fungus that is also an insect pathogen. Its entomopathogenicity is a characteristic that was acquired during evolution from a plant endophyte ancestor. This transition provides a novel perspective on how new functional mechanisms important for host switching and virulence have evolved. From a random T-DNA insertion library, we obtained a pathogenicity defective mutant that resulted from the disruption of a sterol carrier gene (Mr-npc2a). Phylogenetic analysis revealed that Metarhizium acquired Mr-npc2a from an insect by horizontal gene transfer (HGT). Mr-NPC2a binds to cholesterol, an animal sterol, rather than the fungal sterol ergosterol, indicating it retains the specificity of insect NPC2 proteins. Mr-NPC2a is an intracellular protein and is exclusively expressed in the hemolymph of living insects. The disruption of Mr-npc2a reduced the amount of sterol in cell membranes of the yeast-like hyphal bodies that facilitate dispersal in the host body. These were consequently more susceptible to insect immune responses than the wild type. Transgenic expression of Mr-NPC2a increased the virulence of Beauveria bassiana, an endophytic insect-pathogenic fungus that lacks a Mr-NPC2a homolog.

【 授权许可】

CC BY