Comparison of the sub-cellular compartmentation of sugars in mature apples of two cultivars susceptible to different types of watercore and grown in different climates.

摘要

Cellular compartmentation of sugars was compared between mature cv. Orin and Fuji apple which are susceptible to early and late watercore, respectively. Fruits were grown in a warm climate (Ehime) and cool climate (Aomori). Slight watercore, with a score of 1.4 (i.e. a remaining trace of early watercore), was detected in cv. Orin at Ehime, whereas severe late watercore, with a score of 3.0, was observed in cv. Fuji at Aomori. Sorbitol contents were markedly higher in watercored fruits than in non-watercored fruits, not only in intercellular spaces but also in the cytoplasm and vacuoles irrespective of the type of watercore. Permeability of the tonoplast to sorbitol was higher in watercored fruits than in non-watercored fruits in both cultivars, while a lower permeability of the plasma membrane to sorbitol was observed in watercored fruits. Late watercore, which affected cv. Fuji at Aomori, showed similar levels of sorbitol to early watercore in cv. Orin at Ehime, despite the markedly higher watercore score in cv. Fuji, suggesting that sorbitol may play only a minor role as a causative agent in the development of late (or low temp.-promoted) watercore compared with early (or high temp.-induced) watercore.