Elevated carbon dioxide reduces a common soybean leaf endophyte

Authors: CHRISTIAN, NATALIE - University Of Louisville; BASURTO, BALDEMAR - University Of Illinois; TOUSSAINT, AMBER - University Of Illinois; XU, XINYAN - University Of Illinois; Ainsworth, Elizabeth - Lisa; BUSBY, POSY - Oregon State University; HEATH, KATY - University Of Illinois

Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2021
Publication Date: 9/1/2021
Citation: Christian, N., Basurto, B., Toussaint, A., Xu, X., Ainsworth, E.A., Busby, P.E., Heath, K.D. 2021. Elevated carbon dioxide reduces a common soybean leaf endophyte. Global Change Biology. 27(17):4154-4168. https://doi.org/10.1111/gcb.15716.
DOI: https://doi.org/10.1111/gcb.15716

Interpretive Summary: All plant species are colonized by foliar endophytes, which are environmentally-acquired, asymptomatic leaf fungi and bacteria that affect plant physiology and ecology. It is unknown how global atmospheric change will alter crop foliar endophytes and what downstream effects that may have on crop productivity. This study used the Soybean Free Air Concentration Enrichment (SoyFACE) facility to test how elevate carbon dioxide concentrations affect soybean foliar endophytes. The endophyte community composition changed in elevated carbon dioxide with a dominant endophyte, Methylobacterium, decreasing in abundance. Further lab experiments showed that Methylobacterium interacted with many co-occuring fungal microbes. These studies show that global atmospheric change alters endophytic communities, which can affect plant metabolism and interactions with pathogens.

Technical Abstract: Free-air CO2 enrichment (FACE) experiments have elucidated how climate change affects plant physiology and production. However, we lack a predictive understanding of how climate change affects interactions between plants and microbial endophytes, critical mediators of plant physiology and ecology. We leveraged the SoyFACE facility to examine how elevated [CO2] affects soybean (Glycine max) leaf endophyte communities. We then assessed how the dominant endophyte Methylobacterium sp. affects the growth of co-occurring endophytic fungi in vitro. Endophyte community composition changed under elevated [CO2], including a decrease in abundance of a dominant endophyte, Methylobacterium. Methylobacterium abundance was negatively correlated with co-occurring fungal endophytes in the field and antagonistic to co-occurring fungi in vitro. In vitro effects increased in number and magnitude when Methylobacterium was more established in culture prior to fungal introduction. Finally, variation in fungal response to Methylobacterium within a single fungal operational taxonomic unit (OTU) was comparable to inter-OTU variation. By combining in situ and in vitro studies, we show that elevated [CO2] decreases the abundance of a dominant endophyte in soybean that interacts strongly with co-occurring endophytes in culture. Our findings suggest that climate change impacts endophyte interactions with and within plants, and have implications for agricultural and natural systems.