Proceedings of the Third International Conference on Invasive ...

<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaChapter 1: Spartina Biology2) Non-native plants establish symbioses with nativefungi that communicate more efficiently than with nativeplants;3) Non-native plants bring fungi that switch lifestylesand are pathogenic on native plants;4) Non-native plants alter <strong>the</strong> rhizosphere such thatnative root pathogens normally present in low abundancebecome abundant and are more virulent on native plants than<strong>the</strong> non-native species.To begin testing <strong>the</strong> symbiotic communicationhypo<strong>the</strong>sis we have begun to assess <strong>the</strong> fungal endophytes inseveral native and invasive plant species in Puget Sound andnative habitats <strong>of</strong> <strong>the</strong> invasive species. The list <strong>of</strong> plantspecies we are analyzing includes Spartina anglica, S.alterniflora and S. patens. A minimum <strong>of</strong> three populationsfor each plant species was analyzed and at least 10 plants/perpopulation were sampled. All <strong>of</strong> <strong>the</strong> Spartina plantsanalyzed (N=100) contained class 2 endophytes whichappear to be native fungi based on a biogeographic study(Rodriguez et al. in preparation). These endophytes arecurrently being taxonomically defined by sequence analysis<strong>of</strong> nuclear ribosomal DNA and classical morphologicalmethods. The host range <strong>of</strong> <strong>the</strong> endophytes is also beingassessed and culture conditions identified for fungalconidiation. In addition, we have developed methods togerminate Spartina seeds devoid <strong>of</strong> endophytic fungi and arebeginning to perform comparative studies to evaluatesymbiotic and non-symbiotic plants. In 2005-2007 weperformed greenhouse experiments to understand <strong>the</strong>symbiotic dynamics <strong>of</strong> Spartina anglica in <strong>the</strong> presence andabsence <strong>of</strong> abiotic stress. These studies indicated thatSpartina, like native coastal plants, establish associationswith endophytes that confer salt tolerance Rodriguez et al.2008; Rodriguez et al., in preparation). Therefore, wesurmise that endophytes play an important role in <strong>the</strong>invasion <strong>of</strong> coastal areas by Spartina species. Studies areunderway to determine if endophytes contribute to <strong>the</strong>invasion processes in non-coastal habitats that imposedifferent degrees <strong>of</strong> abiotic stress.ACKNOWLEDGMENTSWe would like to thank <strong>the</strong> organizers <strong>of</strong> <strong>the</strong><strong>International</strong> Spartina <strong>Conference</strong> for <strong>the</strong> opportunity topresent <strong>the</strong>se hypo<strong>the</strong>ses and submit this manuscript. Wewould like to thank Edward Pr<strong>of</strong>fitt, David Heimer andRoger Fuller for assistance in collecting Spartina samples.This work was funded in part by grants from <strong>the</strong> U.S.Geological Survey and <strong>the</strong> National Science Foundation.REFERENCESArnold, E.A., L.C. Mejia, D. Kyllo, E. Rojas, Z. Maynard,N. Robbins, and E.A. Herre. 2003. 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