Studies on Fruit Ripening (I)Comparisons of Ripening Parameters, Peroxidase Activity, and Peroxidase Zymograme of Normal and rin Mutant Tomatoes

Abstract

Fruit of tomato (Lycopcrsicum esculentum Mill.) cv. Floradel and of an isogenic mutant rin harvested at mature-green stage were ripened at 21℃ and were measured their activity and zymograme of peroxidase at designated color stages. Ripening of Floradel tomatoes were appeared to follow a pre-determined patterns; peroxidase activity increased about three times when fruit color chranged from mature-green to breaker stage; zymograme of peroxidase changed dramatically during fruit ripening. Rin mutant did not induce peroxidase activity, respiration, and ethylene evolution; fruit color changed to yellow after 99 days; zymograme of peroxidase were not changed; isozyme b and i were not appeared in rin mutant when compared with Floradel cultivar. Failure in ripening of rin mutant is postulated that lack of some isozymes of peroxidase resulting unability to receive activator(s), then to activate peroxidase for ethylene synthesis. 正常後熟蕃茄品種 Floradel 與不後熟單因子突變種 rin 之果實於綠熟期（ Grreen-mature stage ）採收，置於 21℃下後熟。觀察其呼吸率，乙烯放出率，果色及過氧化酶活性與其異性酶圖 ( Zymograme）的變化。 Floradel 果實後熟正常，具有更年期高峰（ Climacteric rise ）現象，過氧化酶活性於後熟初期驟升至原來的三倍，異性酶圖有顯著變化且其異性酶數略有增減。 Rin 果實無法後熟，其呼吸率與乙烯放出率甚低且無顯著變化，果色經久藏漸轉成黃色。在 Floradel 品種出現被命名為 b 及 i 的異性酶並不被發現存在於 rin 品種中。 Rin 品種不後熟的原因被假定為該突變基因在染色體傳訊（ Transcription ）時為一調節基因（ Regulatory gene )，以控制構造基因 ( Structure gene ）生成 activator（s）來活化過氧酶，但該酶因缺少部份異性酶而無法被活化，導致無法製造乙烯來引發果實後熟。