Histological and protein changes during early stages of seed germination in the orchid, Dendrobium crumenatum

Abstract

During germination of seed of the tropical epiphytic orchid, Dendrobium crumenatum, cell division at the chalazal end of the globular embryo occurred after one week of culture on Vacin and Went medium. The larger cells at the middle and basal regions of the embryo continued to enlarge with distinct nuclei and chromatin, indicative possibly of endoduplication. Shoot apex organization at the chalazal end occurred after four weeks of culture. Mobilization of stored reserves was seen as a reduction in the granular nature of the cytoplasm after two weeks in culture. Utilization of protein reserves occurred within 6 d of germination. Subsequently, do nero synthesis and accumulation of cvs proteins increased steadily and reached an equilibrium between 18 and 24 d. Changes in profiles of specific proteins indicated development-specific protein accumulation. Two proteins of Mr 14 and 33 kDa were highly abundant in dry seeds but were degraded within 6 d of germination indicating their possible nutritive role in embryo development. Several other proteins showed steady increases during 24 d from germination.