Transcriptional profiles of a foliar fungal endophyte (Pestalotiopsis, Ascomycota) and its endohyphal bacterium (Luteibacter, Gammaproteobacteria) in co-culture support sulfur exchange and growth regulation

• DOI: 10.1101/2021.11.24.469969
• Publication Date: 2021-11-25T23:20:10Z
• Authors: Justin P. Shaffer; Morgan E. Carter; Joseph E. Spraker; Meara Clark; Brian A. Smith; Kevin L. Hockett; David A. Baltrus; A. Elizabeth Arnold
• Keywords: Endophyte; Pestalotiopsis

ABSTRACT Symbiosis with bacteria is widespread among eukaryotes, including fungi. Bacteria that live within fungal mycelia (endohyphal bacteria) occur in many plant-associated fungi, diverse Mucoromycota and Dikarya. Pestalotiopsis sp. 9143 a filamentous ascomycete isolated originally as foliar endophyte of Platycladus orientalis (Cupressaceae). It infected naturally the endohyphal bacterium Luteibacter 9143, which influences auxin enzyme production by its host. Previous studies have used transcriptomics to examine similar symbioses between root-associated fungi such arbuscular mycorrhizal plant pathogens. However, currently there are no gene expression Ascomycota, most species-rich phylum. We developed methods for assessing when grown co-culture each was axenically. Our assays showed density greater than axenic culture, but opposite true Dual RNA-seq data demonstrate growing modulates developmental metabolic processes both fungus bacterium, potentially through changes balance organic sulfur via methionine acquisition. analyses also suggest an unexpected, potential role bacterial type VI secretion system symbiosis establishment, expanding current understanding scope dynamics fungal-bacterial symbioses. TWEET When co-culture, downregulates motility upregulates T6SS. Gene host, , impacts cell structure availability. IMPORTANCE Interactions microbes their hosts important outcomes host- environmental health. Foliar endophytes infect healthy plants can harbor facultative endosymbionts called bacteria, influence outcome plant-fungus interactions. These bacterial-fungal interactions be influential poorly understood, particularly from transcriptome perspective. Here, we report on comparative, dual study examining patterns cultured together vs. separately. findings support providing acquisition, involvement establishment. This work adds body literature characterizing interactions, focus model two lineages, Ascomycota Proteobacteria.