Study on slowing down in the later stage of tomato fruit enlargement

• Project/Area Number: 19K06020
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39030:Horticultural science-related
• Research Institution: Ehime University
• Principal Investigator: Kataoka Keiko 愛媛大学, 農学研究科, 教授 (80204816)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2021: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000); Fiscal Year 2020: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000); Fiscal Year 2019: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
• Keywords: トマト / 果実肥大 / 低温 / 果皮の機械的強度 / 果皮 / 糖代謝酵素活性 / エチレン

Outline of Research at the Start

成熟に伴う果皮硬化現象を，物理的計測および組織学的観察により確認した上で，塩ストレス，エチレン処理，低温管理により果実発達後期の肥大を制御した場合の，果皮硬化，果実肥大，シンク活性および果皮硬化に関わる酵素活性の様相を明らかにする．

Outline of Final Research Achievements

Tomato fruit growth and fruit skin tensile properties were investigated under low temperature conditions, Ethrel application, or salinity stress in the later stages of fruit growth in a ‘Micro Tom’ tomato variety. Low temperatures prolonged the ripening process and fruit growing continued resulting in a larger size even after pigmentation with photo assimilate influx. In addition to the longer ripening period, a slight restriction of water inflow owing to the elastic fruit skin might allow the fruit to expand under low temperatures.
Fruit growth was retarded three days after Ethrel treatment, but the fruit skin tensile properties were not changed. This means that the fruit skin tensile strength was not responsible for the retardation of fruit growth when treated with Ethrel. Similarly, the firmness because of salinity was not responsible for the reduced fruit growth, as the reduction of fruit size was observed earlier than the fruit skin changes.

Academic Significance and Societal Importance of the Research Achievements

トマト果実肥大後期における果皮の引張特性を検討し，低温管理によって物理的特性が変化することを明らかにした．栽培温度による果実サイズ決定には，エスレルによる成熟促進や塩ストレスによる小果化とは異なるメカニズムが存在することが示唆された．