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Abstract Detail


Symbioses: Plant, Animal, and Microbe Interactions

Beaulieu, Wesley T [1], Panaccione, Daniel G [2], Miller, Richard E [3], Clay, Keith [1].

New Reports of Ergot Alkaloids and Chemotypic Diversity in Convolvulaceae-Clavicipitaceae Symbiosis.

Ergot alkaloids are fungal secondary metabolites well known for their role in plant defense against herbivores. In plants, ergot alkaloids are produced by symbiotic fungi in the family Clavicipitaceae (Ascomycota) first discovered from associations with the Poaceae but now known to be distributed across several mono- and dicotyledonous plant families including the Cyperaceae and more recently the Convolvulaceae. Here we report on a survey of the Convolvulaceae for (1) the presence of fungal ergot alkaloids in seeds and (2) the intra- and interspecific chemical diversity therein. Our results show a worldwide distribution of ergot-positive species including representatives from North, Central & South America, Africa, Australia, Asia and Oceania. Concentrations of ergot alkaloids in the Convolvulaceae ranged from 0.1 to 4700 µg/g seed, which is up to 1000 fold greater than in Clavicipitaceae-Poaceae symbioses. Interestingly, ergot-positive species are restricted to the tribe Ipomoeeae, a group of 900 tropical and sub-tropical species, primarily twining vines. While the previous literature suggested a phylogenetic signal of ergot alkaloid distribution, our expanded survey shows the picture to be more complicated. Our survey of 64 species revealed 19 ergot-positive species, seven of which were previously unreported. 12 ergot alkaloids occurred among these species in 17 different combinations (unique chemotypes). Different chemotypes were detected among accessions in several species, indicating genetic variation of symbionts. There were over 40 instances when a specific ergot alkaloid was detected for the first time in a particular species. Extensive population sampling of two species (Ipomoea parasitica and I. pes-caprae) revealed within species variation in alkaloid presence and concentration, including a significant difference in alkaloid concentrations between geographically separated populations of I. pes-caprae from the Gulf and Atlantic costs of Florida. Given that there are 900 species in the tribe, our results suggest that we have yet to realize the diversity and distribution of the symbiotic relationship between Clavicipitaceae and Convolvulaceae.

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1 - Indiana University, Department of Biology, 1001 E 3rd St, Bloomington, IN, 47405, USA
2 - West Virginia University, Division of Plant & Soil Sciences, 1090 Agricultural Sciences Building, Morgantown, WV, 26506, USA
3 - Southeastern Louisiana University, Department of Biological Sciences, 808 N Pine St, Hammond, LA, 70402, USA

Keywords:
Ergot Alkaloids
Clavicipitaceae
Convolvulaceae
Ipomoea
Symbiosis.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM
Number: PSB004
Abstract ID:670


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