Lack of sexspecific differences in mycorrhizal as

Authors: Jonathan B González Gretel L Clarke Alison K Brody

Publish Date: 2015/05/15

Volume: 216, Issue: 7, Pages: 951-962

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Abstract

For decades evolutionary plant biologists have been interested in how females reap a fitness advantage and are thus maintained in gynodioecious plants Recent attention has focused on the role of multispecies interactions in the maintenance of females wherein the role of arbuscular mycorrhizal fungi AMF is virtually unknown AMF form symbiotic associations with plants often resulting in enhanced nutrient acquisition and tolerance to biotic and abiotic stress Depending on the degree to which females and hermaphrodites rely on their AMF partners AMF could differentially affect plant tolerance to stress We conducted a field experiment to examine 1 if females and hermaphrodites of the gynodioecious herb Polemonium foliosissimum differentially associate with AMF and 2 if there was a difference in AMF colonization between the sexes after imposing stress by simulating herbivore damage First we compared mycorrhizal colonization between the sexes under ambient ie undamaged field conditions Then for a second set of plants we simulated herbivory by clipping plants and compared mycorrhizal colonization leaf phosphorus concentration P and fruit and seed production between clipped and control plants Mycorrhizal colonization did not differ between sexes under ambient field conditions or under the stress imposed by clipping Clipping did however influence both percent root length and vesicle colonization in a plantsizedependent manner Overall colonization and vesicle number increased with plant size for clipped plants but decreased with size for nonclipped plants Leaf P did not differ between the sexes nor was influenced by clipping and leaf P was not associated with mycorrhizal colonization Furthermore neither fruit set nor seed production was associated with mycorrhizal colonization Our findings suggest that the sexes of P foliosissimum do not differentially associate with nor differentially garner benefit from mycorrhizal fungi However a complete accounting of the costs and benefits of AMF for gynodioecious species must encompass the full lifehistory of the plantSpecial thanks to the staff and scientists at RMBL and members of the Brody and Gotelli Labs We thank Joe Morton and Renee Petipas for helpful comments during the design of the study We thank Jeanne Harris and Jim Vigoreaux and two anonymous reviewers for constructive criticism of earlier versions of this manuscript and Alan Howard and Ruth Mickey for help with the statistical analysis JBG was supported by a National Science Foundation REU grant to RMBL DBI 0753774 a University of Vermont College of Agriculture and Life Sciences FUSE grant and an Honors College grant

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