Pervasive Effects of Wildfire on Foliar Endophyte Communities in Montane Forest Trees

Abstract

Plants in all terrestrial ecosystems form symbioses with endophytic fungi that inhabit their healthy tissues. How these foliar endophytes respond to wildfires has not been studied previously, but is important given the increasing frequency and intensity of severe wildfires in many ecosystems, and because endophytes can influence plant growth and responses to stress. The goal of this study was to examine effects of severe wildfires on endophyte communities in forest trees, with a focus on traditionally fire-dominated, montane ecosystems in the southwestern USA. We evaluated the abundance, diversity, and composition of endophytes in foliage of Juniperus deppeana (Cupressaceae) and Quercus spp. (Fagaceae) collected contemporaneously from areas affected by recent wildfire and paired areas not affected by recent fire. Study sites spanned four mountain ranges in central and southern Arizona. Our results revealed significant effects of fires on endophyte communities, including decreases in isolation frequency, increases in diversity, and shifts in community structure and taxonomic composition among endophytes of trees affected by recent fires. Responses to fire were similar in endophytes of each host in these fire-dominated ecosystems and reflect regional fire-return intervals, with endophytes after fire representing subsets of the regional mycoflora. Together these findings contribute to an emerging perspective on the responses of diverse communities to severe fire, and highlight the importance of considering fire history when estimating endophyte diversity and community structure for focal biomes.

Fungal communities living within leaves of native Hawaiian dicots are structured by landscape-scale variables as well as by host plants

“…We tested leading hypotheses about the effects of climate, geographic distance, and host identity using this system, and for the most part, found them to be strong predictors of differences in FEF communities between samples -even when the measurements were taken at relatively coarse resolution (Table 1). We found that elevation (Zimmerman & Vitousek, 2012), host plant phylogenetic difference (Unterseher et al, 2012;Kembel & Mueller, 2014;Massimo et al, 2015;Huang et al, 2016;Vincent et al, 2016), spatial (U'Ren et al, 2012), and habitat type (Jumpponen & Jones, 2009Kato et al, 2017) hypotheses all held true to varying extents in our analysis (Figure 3). We found limited (but significant) support for the hypothesis that rainfall structures FEF communities (U'Ren et al, 2012;Zimmerman & Vitousek, 2012), and we also found that evapotranspiration, which had not been previously considered as an important variable, was a significant predictor of difference in FEF communities across the Hawaiian archipelago.…”

“…Unlike elevation, rainfall, and evapotranspiration, which have each been used to model FEF community dissimilarity by only a handful of studies, patterns of host association in FEF communities have been thoroughly documented (Unterseher et al, 2012;Kembel & Mueller, 2014;Massimo et al, 2015;Huang et al, 2016;Vincent et al, 2016;Kato et al, 2017). Thus, it is not surprising that phylogenetic difference among host plants was a statistically significant predictor of FEF community dissimilarity in our analysis (Figure 3).…”

“…In fact, the bulk of FEF research is represented by studies focusing on a specific host plant (Jumpponen & Jones, 2010;Zimmerman & Vitousek, 2012;Mejía et al, 2014;Saucedo-García et al, 2014;Oono et al, 2015;Polonio et al, 2015;Felber et al, 2016;González-Teuber, 2016;Kato et al, 2017). Studies that have surveyed FEF or other leaf-associated fungi across multiple plant species have found significant host effects (Unterseher et al, 2012;Kembel & Mueller, 2014;Massimo et al, 2015;Huang et al, 2016;Vincent et al, 2016), suggesting that host identity likely interacts with the abiotic environment to structure FEF community composition. Furthermore, many previous studies used culture-dependent methods to characterize FEF communities, which may not account for the large proportion of microorganisms (fungi included) that are difficult or impossible to isolate on artificial media.…”

A Taxonomic and Phylogenetic Investigation of Conifer Endophytes of Eastern Canada

“…and "Ascomycota sp.". Accordingly, many endophyte studies report endophyte taxa that are often unidentified to species or even genus , U'Ren et al 2012, Huang et al 2016).…”

“…These results provide insight into the complex life histories of conifer needle endophytes and present a straightforward strategy to identify unknown endophyte cultures and sequences by considering the biology and ecology of the whole fungus.INTRODUCTIONIncreasing research interest in the biodiversity and functional ecology of endophytes has stimulated extensive cultivation and sequencing efforts to investigate endophytes from a wide range of host plants worldwide. However, in such studies most representative endophyte taxa are often unidentified to species or genus, U'Ren et al 2012, Huang et al 2016). Endophytes are difficult to identify because of a lack of taxonomically informative cultural characters and a paucity of relevant reference sequences in databases such as NCBI GenBank or UNITE(Kõljalg et al 2005).…”