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Mycorrhizal Specificity (mycorrhizal + specificity)
Selected AbstractsTHE EVOLUTIONARY HISTORY OF MYCORRHIZAL SPECIFICITY AMONG LADY'S SLIPPER ORCHIDSEVOLUTION, Issue 6 2007Richard P. Shefferson Although coevolution is acknowledged to occur in nature, coevolutionary patterns in symbioses not involving species-to-species relationships are poorly understood. Mycorrhizal plants are thought to be too generalist to coevolve with their symbiotic fungi; yet some plants, including some orchids, exhibit strikingly narrow mycorrhizal specificity. Here, we assess the evolutionary history of mycorrhizal specificity in the lady's slipper orchid genus, Cypripedium. We sampled 90 populations of 15 taxa across three continents, using DNA methods to identify fungal symbionts and quantify mycorrhizal specificity. We assessed phylogenetic relationships among sampled Cypripedium taxa, onto which we mapped mycorrhizal specificity. Cypripedium taxa associated almost exclusively with fungi within family Tulasnellaceae. Ancestral specificity appears to have been narrow, followed by a broadening after the divergence of C. debile. Specificity then narrowed, resulting in strikingly narrow specificity in most of the taxa in this study, with no taxon rewidening to the same extant as basal members of the genus. Sympatric taxa generally associated with different sets of fungi, and most clades of Cypripedium -mycorrhizal fungi were found throughout much of the northern hemisphere, suggesting that these evolutionary patterns in specificity are not the result of biogeographic lack of opportunity to associate with potential partners. Mycorrhizal specificity in genus Cypripedium appears to be an evolvable trait, and associations with particular fungi are phylogenetically conserved. [source] High specificity generally characterizes mycorrhizal association in rare lady's slipper orchids, genus CypripediumMOLECULAR ECOLOGY, Issue 2 2005RICHARD P. SHEFFERSON Abstract Lady's slipper orchids (Cypripedium spp.) are rare terrestrial plants that grow throughout the temperate Northern Hemisphere. Like all orchids, they require mycorrhizal fungi for germination and seedling nutrition. The nutritional relationships of adult Cypripedium mycorrhizae are unclear; however, Cypripedium distribution may be limited by mycorrhizal specificity, whether this specificity occurs only during the seedling stage or carries on into adulthood. We attempted to identify the primary mycorrhizal symbionts for 100 Cypripedium plants, and successfully did so with two Cypripedium calceolus, 10 Cypripedium californicum, six Cypripedium candidum, 16 Cypripedium fasciculatum, two Cypripedium guttatum, 12 Cypripedium montanum, and 11 Cypripedium parviflorum plants from a total of 44 populations in Europe and North America, yielding fungal nuclear large subunit and mitochondrial large subunit sequence and RFLP (restriction fragment length polymorphism) data for 59 plants. Because orchid mycorrhizal fungi are typically observed without fruiting structures, we assessed fungal identity through direct PCR (polymerase chain reaction) amplification of fungal genes from mycorrhizally colonized root tissue. Phylogenetic analysis revealed that the great majority of Cypripedium mycorrhizal fungi are members of narrow clades within the fungal family Tulasnellaceae. Rarely occurring root endophytes include members of the Sebacinaceae, Ceratobasidiaceae, and the ascomycetous genus, Phialophora. C. californicum was the only orchid species with apparently low specificity, as it associated with tulasnelloid, ceratobasidioid, and sebacinoid fungi in roughly equal proportion. Our results add support to the growing literature showing that high specificity is not limited to nonphotosynthetic plants, but also occurs in photosynthetic ones. [source] | ||||||||||