Workman, Rachael , Cruzan, Mitchell .
Plant-fungal interactions as mediators of invasive plant competition.
Invasive plants pose worldwide economic and ecological risks. However, despite public interest and extensive research into the mechanisms supporting exotic invasion, conclusions regarding the means by which invasives become so competitively successful remain elusive. One of the lesser studied mechanisms which may support exotic invasion are the novel feedback interactions with soil biota, including arbuscular mycorrhizal fungi (AMF). AMF are obligate plant symbionts whose associations range on a continuum from mutualistic to parasitic; however, they are generally regarded as mutualists.Ideally, AMF increase nutrient and water availability for the plant, and in return, receive carbon from the host in the form of photosynthates. AMF are known to be influential in shaping community structure and competitive interactions between plants by differentially colonizing and allocating resources to their hosts. The formation of common mycelial networks (CMNs) between plants has been hypothesized as a mechanism for this preferential allocation by means of shuttling nutrients, carbon and even defense signals between connected hosts. I hypothesize that a decreased dependency on AMF(dependency being established by calculating difference in growth between plants with and without AMF inoculums) can attribute to invasive plant competitive success, and that mycorrhizal-mediated parasitism occurs between the invasives and natives by means of CMNs. I propose to explore these hypotheses with two experiments. First, I will place the invasive grass Brachypodium sylvaticum and its native competitor, Bromus carinatus, in inter- and intraspecific competitive pairings. Each pairing will be subjected to sterile and fungicidal treatments, as well as inoculated with rhizospheric field soil containing AMF communities from either an invaded or adjacent uninvaded range. Secondly, these competitive pairs will be placed in pots containing either a solid divider which will serve to block below ground competition, a mesh divider which will block root interactions but allow for CMN formation, and a control with no divider. In tandem, these two experiments have the potential to elucidate if the invasive alters its soil biota community on a small scale, if this alteration is important, and if so provide a mechanism for how an invasive might exploit native mutualisms in order to achieve competitive success.
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1 - Portland State University, Biology, 1719 SW 10th Ave, SRTC Room 246, Portland, OR, 97201
2 - Portland State University, Department Of Biology, PO BOX 751, PORTLAND, OR, 97207, USA
Presentation Type: Poster:Posters for Sections
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM