EXTRACELLULAR (GLYCO)PROTEINS IN EMBRYOGENIC AND NONEMBRYOGENIC CELL-LINES OF CARIBBEAN PINE - COMPARISON BETWEEN PHENOTYPES OF STAGE ONE SOMATIC EMBRYOS

This work was aimed at characterizing, at the extracellular level, the embryogenic state in cell cultures of Caribbean pine, and discriminat ing between cell lines expressing different phenotypes of early-stage somatic embryos. In this species somatic embryogenesis proceeds throug h the four stages commonly described in conifers. Our study was focuse d on Stage one somatic embryos. Extracellular proteins were extracted from four embryogenic and two non-embryogenic cell lines of Pinus cari baea var. hondurensis. The proteins analysed by one and two-dimensiona l gel electrophoresis differed greatly between the two groups of cultu res, while all embryogenic cell lines showed strong similarities. Extr acellular proteins located in the high and mid-molecular ranges could bind concanavalin A but could also immunoreact with an antibody direct ed against complex N-linked glycans containing alpha 1 --> 3 fucose an d/or beta 1 --> 2 xylose. Due to the constancy of their extracellular protein patterns, minor reproducible differences could be correlated t o the phenotypes of the Stage one somatic embryos. One polypeptide (27 .6 kDa) was associated with the normal phenotype while another polypep tide (33.5 kDa) was well represented in one cell line exhibiting abnor mal development. These results suggest that extracellular (glyco)prote in are correlated with the differentiation of somatic embryos in Carib bean pine.