Morphological aspect of blossom-end rot fruits of tomato.

摘要

A high incidence of blossom-end rot (BER) fruits is a serious problem in tomatoes grown in hydroponics, especially in hot summer seasons. We examined the morphological aspects of BER under light and electron microscopes. BER started as a fluid-soaked area which appeared on the surface of fruits; this area turned black/corky dark brown. Cells that exhibited abnormal structure appeared in the epidermal and sub-epidermal layers at first. Electron microscopic observation showed that: (1) disruption ofplasma membrane and tonoplast occurred; (2) the cell wall was wavy-shaped; (3) the endoplasmic reticulum was broken down; and (4) the plastids became swollen. The peripheral cells around necrotic tissues of BER had normal internal structure, but the plasma membrane was detached from the cell wall, suggesting occurrence of plasmolysis. The phenomenon of plasmolysis was rarely observed at other parts of fruits distant from the part of BER and in the cells of normal fruits. In fruits with BER, the sub-epidermal cells were broken down. Some cells around broken cells showed deposition of lignin, and peripheral cells showed meristematic structure like callus. It is thought that they are the response of wound healing of tomato fruits.