Cell Wall Changes in Juice Vesicles Associated with “Section Drying” in Stored Late-harvested Grapefruit

Normal and collapsed juice vesicles were removed from stored late-harvested grapefruit segments ( Citrus paradisi Macf. cv. Marsh) and the cell wall anatomy of epidermal and internal parenchyma was compared with light, scanning electron, and transmission electron microscopy. Normal juice vesicles were turgid and elongate, and epidermal cells and internal parenchyma were intact. Collapsed juice vesicles appeared flattened, and internal parenchyma were compressed. Cell wall thickening occurred in internal parenchyma and single or clustered epidermal cells of collapsed vesicles. Cell walls of the same cells in normal vesicles were thin. Epidermal and internal parenchyma cell walls of collapsed vesicles were 10 to 50 to 10 to 20 times the thickness, respectively, of corresponding normal cell walls. Lignin was detected in thickened cell walls of epidermal and internal parenchyma of collapsed vesicles. The results suggest that cell wall synthesis in vesicles is a symptom of section drying in grapefruit.