Poster: Late and Moved Abstracts

Abs # 1364: Comparing the roles of B3 domain transcription factors FUSCA3 and LEAFY COTYLEDON2 during embryogenesis

Presenter:	Pelletier, Julie , jpelletier@ucdavis.edu
Authors	Pelletier, Julie  (A)   Matsudaira Yee, Kelly  (A)   Stone, Sandra L. (A)   Kwong, Linda W. (A)   Fischer, Robert L. (B)   Goldberg, Robert B. (C)   Harada, John J. (A)
Affiliations:	(A): Section of Plant Biology, Division of Biological Sciences, University of California, One Shields Avenue, Davis, CA 95616 (B): Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 (C): Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90024

During embryogenesis, a single-celled zygote differentiates into a mature embryo through a series of highly coordinated events. Arabidopsis LEAFY COTYLEDON genes, LEC1, LEC2, and FUS3, are central regulators of embryo development that play essential roles during the early morphogenesis and late maturation phases of embryogenesis. Ectopic, postembryonic expression of either LEC1 or LEC2 confers embryo-like characteristics to seedlings and induces somatic embryo formation from vegetative cells. Thus, the LEC genes are sufficient to establish a cellular environment that promotes embryo development. All three LEC genes encode transcription factors; LEC2 and FUS3 constitute a family of closely-related members of the plant-specific B3 domain proteins. Given the close relationship between LEC2 and FUS3, we investigated the extent to which they overlap functionally during embryo development. We showed that fus3 and lec2 mutant embryos display similar but distinct morphological and physiological abnormalities. Furthermore, FUS3 and LEC2 genes exhibit different temporal expression patterns during embryogenesis. Consistent with the conclusion that the two genes have distinct roles in embryo development, epistasis analysis shows that they do not act linearly in the same pathway. However, ectopic expression of these genes induces similar changes, both at a morphological and molecular levels. We suggest that although FUS3 and LEC2 play specific roles during embryogenesis, they may act through similar mechanisms.