Dr. Jeffrey A. Rollins
Phone: (352) 273-4620
Office: Rm. #1419, Fifield Hall
2550 Hull Road
Gainesville, FL, 32611
My research program explores the basic molecular mechanisms underlying fungal pathogenesis and fungal development. These investigations are largely focused on the broad host range phytopathogenic fungus Sclerotinia sclerotiorum. The long-term goal of my program is to understand how fungi perceive stimuli from the ambient environment and transduce this information into gene-specific responses. We are applying organismal-, molecular genetic-, and genomic-scale tools to identifying and characterizing components of signal transduction pathways that are required for the broad host range pathogenicity and multicellular development of this fungus.
Ph.D. Botany & Plant Pathology, Purdue, 1996
M.S. Plant Pathology, North Carolina State University, 1991
B.S. Biological Sciences, North Carolina State University, 1988
Fungal Plant Pathogens
Pathogenic Mechanisms. In planta and in culture, S. sclerotiorum produces a diverse set of cellulytic enzymes and a high concentration of oxalic acid. These factors have been implicated to act synergistically and to be essential for pathogenicity. Long-standing observations have suggested that oxalic acid production and the activities of secreted hydrolytic enzymes produced are regulated by environmental pH. A working hypothesis within my group is that environmental pH also serves as a signal for gene-specific regulation of these processes. This hypothesis has served as the impetus for studies to identify and characterize an ambient pH-responsive signal transduction system in S. sclerotiorum. We have identified and partially characterized a S. sclerotiorum gene, pac1, encoding a zinc finger-containing peptide with structural and functional homology to the Aspergillus nidulans pH-responsive transcription factor PacC. Functional analysis of Pac1 via gene replacement in S. sclerotiorum was utilized to determine that the ambient pH-sensing pathway is important in regulating virulence and furthermore, required for mature sclerotial development. This work is continuing through the characterization of pac1 gain-of-function mutants and through the identification of downstream Pac1-regulated genes.
Multicellular Development. Sclerotinia sclerotiorum is a stromatic, inoperculate, discomycete. It produces a vegetative, multicelluar, compact, aggregation of hyphae consisting of three distinct layers: a melanized rind layer, an internal, compact cortex layer, and an central medulla layer. This stroma (a sclerotium), is comprised entirely of fungal tissue and is easily separated from the nutritional substrate and undifferentiated fungal hyphae upon which it was formed. Sclerotia play essential roles in the life cycle. They serve as quiescent, long-term survival structures and, when properly conditioned, give rise to the sexual fruiting bodies (apothecia).
We have identified genes that are specifically expressed in sclerotia. Characterization of these genes is revealing insights into their tissue-specific function and into potential pathways regulating sclerotial development (560k Quicktime movie). We have recently initiated studies to molecularly dissect the developmental regulation of apothecia (452k Quicktime movie). Apothecial development is light regulated. We have characterized basic photobiology properties of this regulation and are using this information to synchronize development; physiologically define stages and transitions of development; and identify genes that are specific to key transitional stages.
View a collection of my publications on Google Scholar
Host Parasite Interactions
My teaching program includes the active mentoring of Graduate Students, teaching PLP 6905: Host Parasite Interactions I, and participation in the departmental core curriculum.