Systematics/Phytogeography / Taxonomie/ Section
Bérubé, Vicky , Lechowicz, Martin , Waterway, Marcia .
Phylogenetic pattern in the ability of North American sedges (Carex, Cyperaceae) to form dauciform roots in low phosphorus conditions.
Specialized carrot-shaped roots, termed dauciform roots, were first described from a few European sedges (Cyperaceae) in 1966, and have subsequently been shown to occur on several Australian sedge genera. Experimental studies in Australia have confirmed their role in facilitating phosphorus (P) uptake and demonstrated that they can be induced under low P conditions. We report the first North American observations of dauciform roots on 8 of 18 examined Carex species in northern Quebec peatlands and illustrate the morphology of these specialized roots in Carex. We also compared 62 species of Carex in a greenhouse experiment using three replicates of complete and low P nutrient treatments to assess phylogenetic differences in capability to induce these roots under low P conditions. Species were chosen to represent the three subgenera of Carex in North America and to assess consistency of dauciform root induction within clades of subgenus Carex. None of the five tested species of subgenus Vignea formed dauciform roots under complete or low P treatments. In contrast, dauciform roots were induced on 86% of the 55 tested species of subgenus Carex and both tested species of subgenus Psyllophora in the low P treatment. Only 12% of these species (all in subgenus Carex) also formed a few dauciform roots in the complete nutrient treatment. Within subgenus Carex, dauciform roots were induced in all tested species of 10 clades, including multiple species in sections Acrocystis, Careyanae, Granulares, Griseae, Hymenochlaenae, Lupulinae, Laxiflorae, Paniceae, Squarrosae, Vesicariae but were induced only rarely or not at all in species of sections Limosae and Phacocystis. In contrast to the clear phylogenetic pattern, there was no apparent relationship to habitat type.
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1 - McGill University, Plant Science, 21,111 Lakeshore Road, Ste. Anne de Bellevue, Quebec, H9X 3V9, Canada
2 - McGill University, Department of Biology, 1205 Avenue Dr. Penfield, Montreal, Québec, H3A 1B1, Canada
3 - McGill University, Department of Plant Science, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Québec, H9X 3V9, Canada
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM