Relationship between Internal Black Spot of Cabbage and Cell Death

The cause of internal black spot of cabbage has been speculated to be cold damage. However, in this study, we hypothesized that an acute temperature increase in the cabbage head can also be a cause, and conducted a detailed analysis on temperature change inside the cabbage head leaves and the effect of the formation of ice. Inside the cabbage leaves in winter, water droplets often froze and formed ice. Under sunny conditions, the temperature inside the cabbage leaves rose very quickly, and cell death occurred. When ice formation was induced at −5°C, cell death was induced within 60 min in all tested samples. Cell death was confirmed by tripan blue staining. Thus, we concluded that rapid thawing of frozen leaves by an acute temperature increase inside cabbage head leaves can cause damage to the cells, resulting in internal black spot.