Predicting plant responses to mycorrhizal: integrating evolutionary history and plant traits

Authors: Reinhart, Kurt; WILSON, GAIL - Oklahoma State University; Rinella, Matthew - Matt

Submitted to: Ecology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2012
Publication Date: 6/1/2012
Citation: Reinhart, K.O., Wilson, G.W., Rinella, M.J. 2012. Predicting plant responses to mycorrhizal: integrating evolutionary history and plant traits. Ecology Letters. 15:689-695.

Interpretive Summary: • Problem- Mycorrhizae have been underutilized as a management tool because of the lack of understanding of how mycorrhizae benefit most plant species and lack of tools to accurately predict which plants will benefit most from mycorrhizal fungi. Better generalizations about plant-mycorrhizal interactions are needed. • Accomplishment- Subfamilies of grasses, which often represent the majority of biomass in grasslands, exhibited notable variation in their responses to mycorrhizal fungi. Tests confirmed that closely related plant species interactions with mycorrhizal fungi were more similar than predicted by chance. However, these associations were often weak and explained only some of the variation among plant species. • Theoretical implications- Variation in plant responses to mycorrhizal fungi varied by plant phylogeny. • Management implications- This study identified important phylogenetic patterns for ecologically important plant taxa and illustrates the benefit (though limited) of having plant-mycorrhizae information for closely related species to gauge the benefits of mycorrhizae on other species with unknown interactions with mycorrhizae.

Technical Abstract: The importance of mycorrhizae to most individual plant species is unknown, and responses to mycorrhizal fungi are known to vary among plant species. This complicates interpreting the extent that mycorrhizae affect plant populations, communities, and ecosystems and contributes to their underutilization as a tool in restoration and other applied fields. Here we assess the value of phylogentic relatedness as a tool for predicting plant responses to mycorrhizae. Specifically, we assess whether known responses to mycorrhizae by certain plant species are informative predictors of phylogenetically similar species with unknown responses to mycorrhizae. To perform this assessment, we constructed a phylogenetic tree for 95 tallgrass prairie species with known root colonization by arbuscular mycorrhizal fungi (AMF) and changes in growth due to AMF colonization. Plant responses to mycorrhizae and root colonization both exhibited a phylogenetic signal. One phylogenetic pattern to emerge was the variation in responses to AMF among the subfamilies of grasses (Poaceae). This finding is important for understanding the impact of AMF on plant community and ecosystem properties since many of the world’s major grasslands are dominated by a small number of grass species. Despite the observed phylogenetic signals for traits, phylogenetic relatedness was a faulty predictor of mycorrhizal effects and associations. In part, this is because several non-grass species have independently evolved to be unresponsive to AMF. Our study illustrates the complex associations among species and constraints of using phylogeny to predict how a species will interact with AMF.