The Orchid Protocorm

A protocorm is a characteristic structure in the life of an orchid. The essential organization of the protocorm is formed during embryogenesis. At the time of seed germination, the embryo enlarges and transforms directly into a protocorm. A cell size gradient is noted, with smaller cells located at the apical (chalazal) end and larger cells at the basal (micropylar) end. Smaller apical cells are dedicated to shoot meristem formation, while the larger basal cells are designed to accommodate the mycorrhizal fungi, ensuring nutrient supplies. Based on critical morphogenetic events, the progression of protocorm development to seedling is broadly divided into three phases: the shoot meristem-forming phase, the pre-seedling phase, and the seedling stage. Defining phases/stages in a biological process enables better focus on crucial events, allowing further physiological and biochemical studies and the discovery of regulatory mechanisms of morphogenetic changes.