The plant cell wall is modified as part of many physiological processes. One of the most important classes of enzymes for cell-wall catabolism is cellulases. Dr. del Campillo will attempt to identify the cellulase genes involved in floral-organ abscission (shedding from the parent body) in Arabidopsis and to determine their function in the process. She will test the hypothesis that abscission of each floral organ, i.e., petal, sepal and stamen, is sequential and coordinated, and that abscission of each organ requires several types of enzymes and principally involves two classes of cellulases. One class is up-regulated and involved in the production of intertissue signal(s) and/or in the actual cell-cell separation process, and another class is down-regulated and involved in cell-wall maintenance. Dr. del Campillo will search for and select up-regulated and down-regulated cellulase genes. She then will analyze the spatial and temporal expression of these genes by in situ hybridization experiments to be conducted in collaboration with Dr. Zhongchi Liu in the Department of Plant Biology at the University of Maryland, College Park. She also will analyze the pattern of cellulase expression in abscission-defective mutants isolated by Dr. Anthony Bleecker in the Botany Department of the University of Wisconsin, Madison. Dr. del Campillo will attempt to identify Arabidopsis T-DNA insertional mutants with impaired expression in the selected cellulase genes. Once cellulase mutants are obtained for both the up- and down-regulated abscission cellulases, crosses will be attempted in order to obtain stable double mutants, to determine if coordinated gene expression of both cellulases is required for abscission. All abscission experiments will be conducted in collaboration with Dr. Bleecker.
