Penstemon cardwelliiHyobanche rubraSarcodes

Penstemon cardwelliiHyobanche rubra Sarcodes sanguinea

Andrea D. Wolfe Research Interests


I have two main areas of research in my lab, including the biosystematics of Penstemon and related genera of tribe Cheloneae (Scrophulariaceae) and the molecular evolution of nuclear and plastid genes in plant lineages containing nonphotosynthetic members.

Plant systematics

Currently there are three projects focusing on Penstemon, which revolve around a phylogenetic reconstruction of the genus. The first project involves a collaboration with several ecologists to examine the evolution of pollen presentation theory in a genus having great variation in anther morphology and pollination mechanisms, as well as numerous apparent shifts in pollination modes such as from bee to bird. A phylogenetic reconstruction of as many as possible of the 250+ species of Penstemon is underway using chloroplast and nuclear restriction site and sequence data.

The second project focuses on the biosystematics of subgenus Dasanthera. The sixteen taxa in subg. Dasanthera represent the woody species of Penstemon, and this subgenus is sister to all other subgenera of Penstemon. There are purportedly two examples of diploid hybrid speciation in subg. Dasanthera and we are using chloroplast and nuclear markers to test these hypotheses and to examine patterns of hybridization in this group.

The third project involves the use of ISSR markers to assist in the evaluation of phylogenetic relationships within Penstemon.

Molecular Evolution

Plants that lack chlorophyll do not have a functional photosynthetic apparatus. The lack of chlorophyll is a lethal mutation unless the plant has access to a source of reduced carbon. Parasitic plants have adapted to a heterotrophic lifestyle in that they are attached to a host plant, and the host plant provides the parasite with products of photosynthesis (reduced carbon). Because parasitic plants have circumvented the need to make their own food, the photosynthetic apparatus is under relaxed functional constraint (i.e., the selective pressures to maintain photosynthetic function are eased). Parasitic plants that have adapted to complete heterotrophy (holoprasites) have dramatic changes in the plastid genome for genes encoding proteins involved in photosynthesis.

The major project in the lab is an investigation of parasitic plants of the Ericaceae (Pyrola, Monotropa, Allotropa, Pterospora, Sarcodes, Hypopitys, Hemitomes, Pityopus, Monotropsis, and Pleuricospora). Pyrola includes some nonphotosynthetic members, whereas all of the other genera traditionally circumscribed by the Monotropaceae are nonphotosynthetic. Included in this investigation is a phylogenetic reconstruction of the species of Pyrola and a survey of the plastid and nuclear-encoded photosynthetic genes present or absent in each genus.

Other projects involving parasitic plants focus on the molecular evolution of plastid and nuclear photosynthetic genes in holoparasites of Scrophulariaceae and Orobanchaceae. Recent work in collaboration with Claude dePamphilis revealed that the gene rbcL is intact in plants that have lost photosynthetic ability and that parasitism has arisen once in the Scrophulariales (Wolfe and dePamphilis, 1998; Nickrent et al., 1998)

For additional information on parasitic plants, follow the link to the Parasitic plant connection.

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Wolfe Homepage

Wolfe Lab Homepage

Penstemon Website

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Last updated September 25, 1998.