Epichloë Fungal Endophytes Influence Seed-Associated Bacterial Communities

Abstract

Seeds commonly harbour diverse bacterial communities that can enhance the fitness of future plants. The bacterial microbiota associated with mother plant’s foliar tissues is one of the main sources of bacteria for seeds. Therefore, any ecological factor influencing the mother plant’s microbiota may also affect the diversity of the seed’s bacterial community. Grasses form associations with beneficial vertically transmitted fungal endophytes of genus Epichloë. The interaction of plants with Epichloë endophytes and insect herbivores can influence the plant foliar microbiota. However, it is unknown whether these interactions (alone or in concert) can affect the assembly of bacterial communities in the produced seed. We subjected Lolium multiflorum plants with and without its common endophyte Epichloë occultans (E+, E-, respectively) to an herbivory treatment with Rhopalosiphum padi aphids and assessed the diversity and composition of the bacterial communities in the produced seed. The presence of Epichloë endophytes influenced the seed bacterial microbiota by increasing the diversity and affecting the composition of the communities. The relative abundances of the bacterial taxa were more similarly distributed in communities associated with E+ than E- seeds with the latter being dominated by just a few bacterial groups. Contrary to our expectations, seed bacterial communities were not affected by the aphid herbivory experienced by mother plants. We speculate that the enhanced seed/seedling performance documented for Epichloë-host associations may be explained, at least in part, by the Epichloë-mediated increment in the seed-bacterial diversity, and that this phenomenon may be applicable to other plant-endophyte associations.

Effect of Epichloë gansuensis Endophyte on Seed-Borne Microbes and Seed Metabolites in Achnatherum inebrians

“…Results revealed that seed-borne bacterial communities were mostly dominated by phyla such as Proteobacteria , Actinobacteria , Firmicutes , and Bacteroidetes , and the core genera were Pseudomonas , Bacillus , Sphingomonas , and Allorhizobium . These results were similar to those of the study by Bastías et al, which looked at Lolium multiflorum seeds infected by Epichloë occultans ( 41 ). Previous studies reported that seed-borne fungal communities were dominated by Ascomycota and Basidiomycota ( 42 – 44 ), and those results were in line with the present study.…”

“…Bastías et al not only demonstrated that Epichloë endophytes affected the composition and diversity of the seed microbiota, but they also considered that the bacterial microbes associated with leaf tissues of mother plants are the main source of bacteria for seeds ( 41 ). There were many studies that proved that Epichloë endophytes changed the foliar microbiome community of host plants; for example, the presence of Epichloë coenophiala in tall fescue ( Festuca arundinacea ) modified the leaf-associated fungal communities and the presence of Epichloë festucae var.…”

Epichloë Endophytes Shape the Foliar Endophytic Fungal Microbiome and Alter the Auxin and Salicylic Acid Phytohormone Levels in Two Meadow Fescue Cultivars

“…Although some studies suggested that Epichloë endophytes protect the plant against fungal intruders, such as the ergot fungus in plant seeds, others demonstrated an increased seed infection with ergot fungi on Epichloë -symbiotic plants [ 34 , 35 ]. Furthermore, it has been shown that Epichloë -symbiotic grass seeds show a higher endophytic bacterial diversity compared with Epichloë -free seeds, hence demonstrating their ability to interact with other endophytic microbes [ 36 ]. In leaf tissue, on the other hand, Epichloë endophytes have shown different trends in shaping microbial communities.…”

Single Seed Near-Infrared Hyperspectral Imaging for Classification of Perennial Ryegrass Seed

“…It is known that the resident endophyte alters the physiology of the host seed [ 27 , 28 , 29 , 30 ]. For example, metabolite composition associated with sugars (i.e., mannitol, ribitol and trehalose), antioxidants (i.e., tocochromanols and glutathione) and alkaloid content (peramine, ergovaline and lolitrem B) are altered in Epichloë endophyte-infected seed, which may account for the wider absorbance range in the spectra of E+ compared to E− seed ( Figure 2 ).…”