Ultrastructural and Histochemical Changes during the Germination of Cattleya aurantiaca (Orchidaceae)

Abstract

Germination and protocorm development in Cattleya aurantiaca were examined ultrastructurally and histochemically. Mature, unimbibed seeds contained numerous protein and lipid bodies but no appreciable carbohydrate reserves. Protein bodies were restricted to the upper two-thirds of the embryo. Lipid reserves were utilized slowly in seeds sown aseptically onto medium lacking a carbohydrate source but more rapidly on medium containing sucrose. Degenerating lipid bodies were often found closely associated with mitochondria, but glyoxysomes were not evident at any time during germination. Neither dictyosomes nor rough endoplasmic reticulum was found in the cells of seedlings grown on sugarless medium.