Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Duell, Eric [1], Baskin, Bailey [1], Fishbein, Mark [2], Wilson, Gail [1].

Interspecific variation in relative mycorrhizal responsiveness: an Asclepias case study.

Arbuscular mycorrhizal (AM) fungi are a common symbiont of most terrestrial vascular plant species and play a large role in influencing plant community structure and ecosystem processes. Plant responses to AM fungi can vary widely across functional groups with functionally similar species often displaying similar responses to AM symbioses. While plant functional group may explain much of the variation in mycorrhizal associations of plants within a community, variation in responses within genera has been observed and may be explained in part by phylogenetic relatedness. Milkweeds (Asclepias) are a diverse genus of plants in the milkweed and dogbane family (Apocynaceae), with 130 of the estimated 400 species found in North America. Milkweed research has increased dramatically over the past two decades, due in part to its importance as the primary food source of monarch larvae. However, relatively little research exists examining the relationship between AM fungi and milkweeds. Understanding the responsiveness, or dependence, of milkweed species on this symbiosis may be vital to successful restoration efforts that include these species. Our research was conducted at greenhouse facilities at Oklahoma State University, Stillwater, OK. Thirty-one species of milkweed found across the United States were selected to assess the relative mycorrhizal responsiveness (rMR). All seedlings were grown in sterile soil collected from native prairie sites, and half of the plants were inoculated with 20 g-1 of whole prairie soil with intact microbial communities. End of season biomass of mycorrhizal and non-mycorrhizal plants was used to calculate rMR. rMR of selected milkweeds varied greatly between species, ranging from 36 to 97%. This was unexpected, based on previous research assessing the variation in responsiveness within genera. However, thirty of thirty-one species of milkweed produced significantly greater (p ≤ 0.05) biomass when grown on media inoculated with whole prairie soil. This suggests that while there is remarkable variation in the degree of responsiveness within the genus, most species receive benefits from the association with AM fungi. Our study is the first to assess rMR of a large number of milkweed species, most of which are known to be consumed by monarch larvae. We found that mycorrhizal colonization of the roots was not correlated to rMR. Evaluation of the phylogenetic component of variation in rMR data suggests that relatedness is an important determinant of responsiveness to AM fungi. Our research indicates the genus Asclepias is broadly responsive to AM fungi, however, interspecific variation is apparent.

1 - Oklahoma State University, Natural Resource Ecology and Management, 008C Agriculture Hall, Stillwater, OK, 74078, United States
2 - Oklahoma State University, Dept Of Plant Biology, Ecology & Evolution, 301 Physical Science, Stillwater, OK, 74078, United States


Presentation Type: Oral Paper
Number: 0011
Abstract ID:448
Candidate for Awards:None

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