CELL WALL CARBOHYDRATE-EPITOPES IN THE GREEN ALGA OEDOGONIUM BHARUCHAE F. MINOR (OEDOGONIALES, CHLOROPHYTA)

JOSÉ M. ESTEVEZ, PATRICIA I. LEONARDI, JOSEFINA S. ALBERGHINA

JOURNAL OF PHYCOLOGY

Año: 2008 vol. 44 p. 1257 - 1258

0022-3646

Cell wall changes in vegetative and suffultory cells (SC) and in oogonial cells from Oedogonium bharuchae Kamat f. minor Vélez (Chlorophyta) were characterized using monoclonal antibodies against several carbohydrate epitopes. Vegetative and SC develop only a primary cell wall (PCW) whereas mature oogonial cells secrete a second wall, the oogonium cell wall (OCW). Based on histochemical and immunolabeling results, (1®4)-b-glucans in the form of crystalline cellulose together with a variable degree of Me-esterified homogalacturonans (HG) and hydroxyproline rich-glycoprotein (HRGPs) epitopes were detected in the PCW. The OCW showed arabinosides of the extensin-type and low levels of AGP-glycans but lacked cellulose, at least in its crystalline form. Surprisingly, strong co-labeling in the cytoplasm of mature oogonia cells with three different antibodies (LM-5, LM-6, and CCRC-2) was found, thus suggesting the presence of RG-I like structures. Our results are discussed relating the possible functions of these cell wall epitopes with polysaccharides during oogonium differentiation. This study represents the first attempt to characterize the two types of cell walls in O. bharuchae, comparing their similarities and differences with those of other green algae and land plants. This work represents a contribution to the understanding of how cell walls have evolved from simple to complex organisms.