RAPID MESOCARP CELL ELONGATION ENHANCES GUMMING SYNDROME IN JAPANESE APRICOT (PRUNUS MUME SIEB. ET ZUCC.) FRUIT

摘要

Japanese apricot (Primus mume Sieb. et Zucc.) 'Benisashi' fruit tends to show the physiological disorder of a gumming syndrome, while the fruit known as 'Nanko' rarely show this. The accumulated gum becomes a solid gel during the processing period and the commercial value of the mume pickle is consequently decreased. In the present experiment, gum accumulation in the mesocarp tissue and the cell size of the tissue during fruit growth were observed in the two cultivars. In mid-May, the initiation of the gum duct was observed in vascular bundles in the mesocarp tissue of the two cultivars and plant gum was then observed to accumulate in the duct. No difference in these phenomena was observed between the cultivars until late May. Thereafter, 'Benisashi' developed a gum lump visible to the naked eye during Stage III, while the gum lump of 'Nanko' did not develop to the visible size as shown in 'Benisashi'; the lumps could not be confirmed with the naked eye until the mature stage. 'Benisashi' showed more rapid fruit growth compared with 'Nanko' during Stage III due to explosive mesocarp cell elongation close to the endocarp. Moreover, the rate of gumming fruit of 'Benisashi' was higher in bigger fruits than smaller ones. These results indicate that the peculiar cell growth of 'Benisashi' fruit may accelerate gum lump formation.