A Basic Chitinase-like Protein Secreted by Embryogenic Tissues of Pinus caribaea acts on Arabinogalactan Proteins Extracted from the same Cell Lines

Embryogenic cell lines of Pinus caribaea consist of a high number of somatic embryos. We have previously characterized the embryogenic state by studying the proteins and glycoproteins ionically bound to the cell surfaces of preglobular somatic embryos. The embryogenic tissues and nonembryogenic calli produce proteins of 48 kDa or 56 and 25 kDa, respectively. All of these proteins cross-react with several classes of tobacco chitinases (CHs). These CH-like proteins express a potential chitinase activity on SDS-PAGE gels overlaid with glycol chitin as a synthetic substrate. When an arabinogalactan protein (AGP) fraction from embryogenic tissues substitutes for glycol chitin on gels, only the 48 kDa embryo-specific CH-like protein acts on this substrate, indicating that an interaction between this protein and a specific set of AGPs might exist within embryogenic tissues of Carribean pine.