Internal cause of occurrence of sugar distribution in apple fruit during maturation

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K07589
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Horticultural science
• Research Institution: Chiba University
• Principal Investigator: OHARA Hitoshi 千葉大学, 環境健康フィールド科学センター, 教授 (40160931)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: リンゴ果実 / 糖度分布 / スクロース蓄積 / 糖代謝関連酵素 / スクロースリン酸合成酵素 / 酵素活性 / 遺伝子発現 / アブシシン酸

Outline of Final Research Achievements

In a mature apple fruit, soluble solids and total sugar contents are higher in the calyx end than in the stem end. The internal cause of occurrence of sugar distribution in an apple fruit was investigated during maturation period using ‘Fuji’ apple. The calyx end always contained higher content of sucrose (Su) which is one of the constitutive sugars. The activity of sucrose-phosphate synthase (SPS) tended to be always higher in the calyx end. Moreover the gene expression level of SPS was significantly higher as well in the calyx end. The relationships between Su accumulation and other related enzyme activities and gene expression levels were not found. On the other hand, endogenous abscisic acid (ABA) concentration increased temporarily only in the calyx end. However, Su accumulation was not promoted both in the calyx and the stem end of the fruit applied with exogenous ABA. Therefore, it was not clear whether ABA is related to the promotion of Su accumulation.

Free Research Field

農学

Academic Significance and Societal Importance of the Research Achievements

果実中の糖度分布を明らかにしてきたこれまでの多くの研究は、果実の甘味評価法の改善を目的とするものがほとんどであり、糖度分布が生じる内的原因を探るという目的で行われた研究は極めてわずかであった。また、その原因を探る対象は糖代謝関連酵素活性に限定されており、その対象を糖代謝関連酵素遺伝子および糖輸送体遺伝子の発現ならびに糖代謝との関連が示唆される成熟関連植物ホルモンの内生濃度および外生処理効果などに拡げ、多面から探ったことに本研究成果の学術的意義があり、また、生産現場で常に希求されている高糖度果実生産の技術開発を考える上で参考となる一つの生理学的な知見となる得ることに社会的意義がある。