Location: Range and Livestock ResearchTitle: Plant functional traits and phylogenetic relatedness explain variation in associations with root fungal endophytes in an extreme arid environment Author
Submitted to: Mycorrhiza
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2014
Publication Date: 7/6/2014
Publication URL: http://handle.nal.usda.gov/10113/60232
Citation: Lugo, M.A., Reinhart, K.O., Menoyo, E., Crespo, E., Urcelay, C. 2014. Plant functional traits and phylogenetic relatedness explain variation in associations with root fungal endophytes in an extreme arid environment. Mycorrhiza. 25:85-95. Interpretive Summary: • Problem- Root fungal endophytes may improve the drought tolerance of plants in arid and semi-arid regions. Determination of patterns among plants would enable better prediction of which plants associate with root endophytes and aid interpreting their likely functional importance. However, relatively little is known about root endophytes in these regions, especially an arid region in Argentina. • Accomplishment- This study determined plants associated with endophytes less frequently than expected. We also observed various cases where root endophyte associations were related to plant functional type, plant family, and plant phylogenetic (evolutionary) similarity. • Theoretical implications- These findings suggest that climatic extremes may create situations where expected associations/benefits of root endophytes are unlikely. • Management implications- Our findings suggest plants in some arid regions rely more on morphological and physiological adaptations to drought than on root endophytes to ameliorate drought stress.
Technical Abstract: Since root endophytes may ameliorate drought stress, understanding which plants associate with endophytes is important, especially in arid ecosystems. Here we characterized the root endophytes of 42 plants from an arid region of Argentina. We related colonization by arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSEs) to plant functional type (PFT), plant family, and plant phylogenetic relatedness. Associations with endophytes were less common than expected. We found that PFT, plant family, and plant phylogeny explained relatively large amounts of the variation in associations with root endophytes. Different types of bromeliads exhibited divergent associations with either AMF (terrestrial) or DSEs (epiphytic). Phylogenetic analysis of AMF data revealed similar results for this clade but detected divergent association with DSE across the order Poales (Bromeliaceae and Poaceae). Comparisons of PFTs also revealed that succulents had surprisingly low levels of endophyte associations. Comparisons of PFTs often helped to resolve greater levels of differences among groupings of taxa than other comparisons. Phylogenetic differences generally identified similar patterns of divergence among Bromeliaceae taxa as PFT comparisons of terrestrial vs. epiphytic bromeliads. Phylogenetic analyzes also detected trait conservatism for AMF among five taxa in the suborder Portulacineae and for DSEs among eight taxa in the subclass Rosidae. In many cases, different comparisons (i.e. PFT vs. phylogenetic) revealed complementary findings. Overall, low to moderate levels of endophyte associations were observed; we suggest that plant traits like succulence may obviate the requirement of associations with endophytes in extremely arid environments.