Proceedings of the Third International Conference on Invasive ...

Chapter 1: Spartina Biology<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaRESULTSDistichlis spicata was identified as <strong>the</strong> first non-Spartina host to G3 C. purpurea. In addition, all isolatesoriginating from Spartina densiflora, S. foliosa, S.alterniflora, and S. anglica were identified as belonging toG3 based on genetic analysis. G1 and G3 isolates containedan EcoRI restriction site within <strong>the</strong> 5.8S rDNA, while G2isolates lacked this site, consistent with distinctions among<strong>the</strong>se groups described by Pazoutová et al. (2000). UsingRAPD and AFLP markers, between-group diversity wasextraordinarily high with only less than 5 % <strong>of</strong> markersshared by all members <strong>of</strong> G1, G2 and G3. Within-groupsimilarity for G3 isolates was approximately 40%.DISCUSSIONThe maritime group <strong>of</strong> C. purpurea (G3) has beendistinguished from o<strong>the</strong>r intraspecific groups in this speciesby having an EcoRI site in <strong>the</strong> 5.8S ribosomal DNA, and aunique banding pattern based on RAPD analysis <strong>of</strong> nuclearDNA. Based on <strong>the</strong>se characters, and AFLP analysis, <strong>the</strong>field collections examined in this study from Spartina spp.and Distichlis spicata are representative <strong>of</strong> <strong>the</strong> maritimegroup. The results <strong>of</strong> this study revealed G3 C. purpurea onthree new species, S. foliosa, S. densiflora, and D. spicata.In addition, this study has identified salt marsh (G3) C.purpurea on S. alterniflora where it is invasive: in <strong>the</strong> SanFrancisco Bay, CA and Willapa Bay, WA. Spartinaalterniflora was intentionally introduced into <strong>the</strong> SanFrancisco Bay as seed in <strong>the</strong> 1970s; S. alterniflora wasunintentionally introduced to Willapa Bay, Washington overa century ago (Stiller and Denton 1995; Civille et al. 2005).The impacts <strong>of</strong> C. purpurea on S. foliosa populations are notknown but <strong>the</strong>re is evidence that <strong>the</strong> pathogen can reduceseed production in this species (A. Fisher, 2007). In WillapaBay, <strong>the</strong> impacts <strong>of</strong> C. purpurea on seed production are notknown. However, rates <strong>of</strong> infection are so low, that even if<strong>the</strong> pathogen reduces seed production on individualinfloresences, C. purpurea is unlikely to be a significantfactor for S. alterniflora fecundity.Spartina anglica, host to maritime C. purpurea on <strong>the</strong>coast <strong>of</strong> <strong>the</strong> United Kingdom and now identified as a host inIreland, has a hybrid origin, being derived from native S.maritima and introduced S. alterniflora (Raybould et al.1991). The first incidence <strong>of</strong> C. purpurea on S. anglica andS. townsendii, <strong>the</strong> sterile F1 hybrid <strong>of</strong> S. maritima and S.alterniflora, was reported in Ireland in 1975 (Boyle 1976).While unsure <strong>of</strong> its origin, Boyle argued that this and aherbarium specimen <strong>of</strong> C. purpurea on S. anglica collectedin 1971 were <strong>the</strong> first definitive reports <strong>of</strong> C. purpurea onsalt marsh Spartina spp. in Great Britain and Ireland.Distichlis spicata has been previously identified as ahost to C. purpurea (Sprague 1950), and is currently <strong>the</strong>only known host to G3 outside <strong>the</strong> genus Spartina. Perhapsnot surprisingly, Distichlis and Spartina are closely relatedgenera, belonging to <strong>the</strong> same subfamily (Chloridoideae)Table 1. Origin and host plant <strong>of</strong> C. purpurea isolates.a GroupOriginHostIDBřezno, Czech Republic Dactylis glomerata G1Altamont, AL, USA F. arundinacea G1Lauderdale, AL, USAFestucaarundinaceaG1L’Anse aux meadows,Newfoundland, CanadaLeymus mollis G1Zubri, Czech Republic Poa pratensis G1MacDoel, CA, USA Secale cereale G1Aberdeen, ID, USA Secale cereale G1Hohenheim, Germany Secale cereale G1Phillipsreuth, Germany Dactylis spp. G2Vlčí Pole u Bousova,Czech RepublicMolinia coerulea G2Willapa River, WA, USA Distichlis spicata G3Palix River, WA, USA S. alterniflora G3Dolphin Island, AL, USA S. alterniflora G3Point Reyes NS, CA,USAS. alterniflora G3St. Augustine, FL, USA S. alterniflora G3Marsh Landing, GA, USA S. alterniflora G3Flax River, NY, USA S. alterniflora G3Rhode Island, USA S. alterniflora G3Southriver, NJ, USA S. alterniflora G3Marchwood, UK S. alterniflora G3Dublin, Ireland S. anglica G3Argentina Celpa Marsh,ArgentinaS. densiflora G3Bolinas Lagoon, CA,USAS. foliosa G3Palo Alto, CA, USA S. foliosa G3Mountain View, CA, USA S. foliosa G3San Mateo, CA, USA S. foliosa G3Point Reyes NS, CA,USAS foliosaG3and tribe (Cynodonteae) (Peterson et al. 2001). This suggestsa phylogenetic correspondence between host and pathogen.The range <strong>of</strong> D. spicata includes <strong>the</strong> Atlantic Coast <strong>of</strong> NorthAmerica, <strong>the</strong> Gulf Coast states, Cuba, and <strong>the</strong> Pacific Coast<strong>of</strong> North America, from British Columbia south to Mexico,and South America (Hitchcock 1971). Distichlis spicata istypically found in salt marshes and seashores on moist andalkaline soils, and borders some S. alterniflora marshes inWillapa Bay, WA.In Argentina, G3 C. purpurea was collected from S.densiflora. Spartina densiflora is native to <strong>the</strong> Atlantic andPacific coasts <strong>of</strong> sou<strong>the</strong>rn South America (Mobberley 1956).Based on alkaloid pr<strong>of</strong>ile, Samuelson and Gjerstad (1966)proposed that C. purpurea from Spartina spp. in coastal-44-