EXPRESSION PATTERN OF THE CARROT EP3 ENDOCHITINASE GENES IN SUSPENSION-CULTURES AND IN DEVELOPING SEEDS

Carrot (Daucus carota) extracellular protein 3 (EP3) class IV endochit inases were previously identified based on their ability to rescue som atic embryos of the temperature-sensitive cell line ts11. Whole-mount in situ hybridization revealed that a subset of the morphologically di stinguishable cell types in embryogenic and nonembryogenic suspension cultures, including ts11, express EP3 genes. No expression was found i n somatic embryos. In carrot plants EP3 genes are expressed in the inn er integumentary cells of young fruits and in a specific subset of cel ls located in the middle of the endosperm of mature seeds. No expressi on was found in zygotic embryos. These results support the hypothesis that the EP3 endochitinase has a ''nursing'' function during zygotic e mbryogenesis and that this function can be mimicked by suspension tell s during somatic embryogenesis.