ASU SoLS Faculty: Leslie R. Towill

Leslie Towill received her Ph.D. degree in Botany from the University of Michigan, Ann Arbor, in 1973. Dr. Towill came to ASU in 1975 after being a postdoctoral fellow in Biochemistry at the University of Washington, investigating photoreactivation of UV-irradiated plant viruses.

My research interest is in regulation of the developmental life cycle of homosporous ferns. Fern spores, the functional equivalent of seeds, germinate to form autotrophic gametophytes. Fertilization and early embryo development occur within the gametophyte. The young sporophyte, derived from the embryo, produces vegetative leaves whereas the mature sporophyte produces both vegetative and spore-bearing leaves. A comparison of the regulation of the development of ferns and seed plants is of interest from both functional and evolutionary perspectives.

Previous research in my laboratory focused on the metabolic events associated with the photoinduction of germination of Onoclea sensibilis L. spores. Light through the action of phytochrome induces changes in metabolism of sucrose and starch, early events in the germination process. Further analysis suggested that irradiation causes changes in functional compartmentation that allowed starch anabolism and sucrose catabolism to occur. Out of these studies came the realization that manipulation of sporophyte during spore formation would be necessary to gain an understanding of spore germination. Unfortunately, Onoclea has a long life-cycle and is not amenable to growing in greenhouse situations. Ceratopteris, in contrast, has a short life cycle, is amenable to genetic analysis, and is easily grown in the laboratory. Two projects with Ceratopteris have been initiated in my lab. The first is a proteonomic study of Hn-n wild type spores and an isogenic mutant RN5. RN5 spores germinate rapidly and synchronously whereas Hn-n spores require an after-ripening period. Protein patterns in the two strains are being compared in dry spores and during imbibition and germination. Unique proteins will be further characterized to determine a possible cause of after-ripening. The second project focuses on the physiological roles of auxins in embryo development and establishment of venation patterns in young sporophyte leaves. Results suggest that auxin controls venation patterns, as in seed plants, but that the source of the IAA involved in venation patterning may be in the foot of the young sporophyte, rather than in the margins of the leaves. I also have a strong interest in photomorphogenesis, that is, the development of plants in response to light. I have collaborated with colleagues in the Department of Plant Biology on investigations of photomovement in red alga Porphyridium, of induction of monospore germination in red alga Bangia ,and of the influence of light on peroxisome membrane proteins in sunflower. I have also participated in the development of an interactive web-based course for non-science majors.

Selected Publications | CV (PDF)

Towill, L, J Stutz and R Wijesuriya. (2001). Concepts in Plant Biology: an interactive web-based college course in plant biology including lecture and lab components for non-science majors. Plant Biol 2001: Abstract No. 7.

Morgan, Berube, Geren, and Towill . (1996). Possible interactions of GA3 and IAA with EODFR irradiation on epicotyl growth of cocklebur. Plant Physiol 111S:461.

Jiang, Bunkelmann, Towill, Kleff, and Trealease . (1994). Identification of peroxisome membrane proteins (PMPs) in sunflower (Helianthus annuus L.) cotyledons and influence of light on the PMP developmental pattern. Plant Physiol 106:293-302.