The dark septate endophyte Phialocephala sphaeroides confers growth fitness benefits and mitigates pathogenic effects of Heterobasidion on Norway spruce

作者：Zilan Wen, Eeva Terhonen, Fred O. Asiegbu · 发表于：Tree Physiology · 年份：2021 · DOI：10.1093/treephys/tpab147 · 被引用次数：30 · 研究领域：Mycorrhizal Fungi and Plant Interactions、Plant-Microbe Interactions and Immunity、Plant Pathogens and Fungal Diseases

Forest trees frequently interact with a diverse range of microorganisms including dark septate endophytes (DSEs) and fungal pathogens. Plant defense responses to either individual pathogens or endophytes have been widely studied, but very little is known on the effect of coinfection on host defenses. To study the impact of coinfection or tripartite interaction on plant growth and host defenses, Norway spruce (Picea abies (L.) Karst) seedlings were inoculated with a DSE Phialocephala sphaeroides or with a root pathogen Heterobasidion parviporum Niemela & Korhonen or coinfected with both fungi. The results showed that the DSE promoted the root growth of spruce seedlings. Control seedlings without any inoculum were subjected to sequencing and used as a baseline for identification of differentially expressed genes (DEGs). RNA-seq analysis of seedlings inoculated with P. sphaeroides, infected with H. parviporum or coinfected with both fungi resulted in a total of 5269 DEGs. The majority of DEGs were found in P. sphaeroides-inoculated seedlings. Lignin biosynthesis pathways were generally activated during fungal infections. The pattern was distinct with endophyte inoculation. The majority of the genes in the flavonoid biosynthesis pathway were generally suppressed during fungal infections. A specific transcriptional response to P. sphaeroides inoculation was the increased transcripts of genes involved in jasmonic acid biosynthesis, mitogen-activated protein kinases signaling pathwa...