Studies on postharvest physiology of fruit by using the method for separation of apoplastic and syplastic solution

2004 Fiscal Year Final Research Report Summary

• Project/Area Number: 14560018
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 園芸・造園学
• Research Institution: Yamagata University
• Principal Investigator: MURAYAMA Hideki Yamagata University, Faculty of Agriculture, Associate professor, 農学部, 助教授 (40230015)
• Project Period (FY): 2002 – 2004
• Keywords: apoplast / symplast / apple / watercore / sugar accumulation / Japanese persimmon / deastringency

Research Abstract

First, the method for separation of apoplastic and symplastic solutions of fruit flesh was investigated. As a result, it was found to be possible by using a centrifuge.
This method applied to apple fruit to clarify the mechanism of watercore development. In‘Fuji' apples, the symptom of watercore was observed 30 days before optimum harvest date, and extended as fruit ripened. Concentrations of sucrose, fructose and glucose in apoplastic solution did not significantly change throughout an experimental period, while sorbitol concentration markedly increased as fruit ripened. In symplastic solution, changes in sugar concentrations were small. In‘Yoko' and‘Orin' apples, watercore did not occurred. In these cultivars, sorbitol concentration in apoplastic solution also increased as fruit ripened, but the levels at optimum harvest date in‘Yoko' and‘Orin' apples were one forth and one fifth of that of‘Fuji' apples, respectively.
Secondly, the effect of girdling treatment around the abscission lay er of fruit on watercore development and sugar accumulation in‘Fuji' apples was investigated. Consequently, girdling treatment suppressed the occurrence of watercore during ripening. In control fruit, sorbitol concentrations markedly increased especially in apoplastic solution as fruit ripened. In treated fruit, they did not significantly change and were low levels compared with those of control fruit. These results indicated that the accumulation of sorbitol in apoplast was involved in the development of watercore in apple fruit.
Finally, the method for separation of apoplastic and symplastic solutions applied to Japanese persimmon fruit to clarify the localization of tannin and the mechanism of deastringency of fruit. Thus, tannin concentration was higher in apoplastic solution than that in symplastic solution. In addition, the bonding of tannin in apoplastic solution and acetaldehyde, which rapidly accumulated after treatment, was thought to be related to rapid destringency by CO_2 treatment in Japanese persimmon fruit.