The dynamics of fruit developing, accumulation of fruit sugar components and activities of sucrose metabolizing related enzymes were studied in red bayberry during the period from 54 d after blossoming ( DAB) to mature by using three varieties, Myrica rubra cv. Dongkui, M. rubra cv. Heijing and M. rubra cv. Wenlingdamei. Results indicated that the fruit sugar components were dominated by sucrose, fructose and glucose. Sucrose was the maximum sugar component, about sharing 40% - 50% of the total sugar. The content of the three components firstly performed a slight decline, and then followed a rapid accumulating till to mature. At mature time, the contents of all the three sugar components reached their summits, were 34. 4 -48. 9, 24. 6 -28. 6 and 23. 2 -27. 7 mg·g-1 FW, respectively. The titratable acid contents rose first, then decreased and reached the bottom at full mature time during fruit developing , which was 0.44% - 0. 62%. The activities of sucrose metabolizing enzymes, including acid invertase (AI), neutral invertase (NI) and sucrose synthase (decomposing direction, SSD) showed a similar trend. Their activities declined first to low level, then rose gradually and got to their highest at full mature time, they were 40. 3 - 52. 8, 31. 2 - 40.5 and 3. 5-4.0 mg glucose· g-1 FW, respectively. The order of enzyme activity from high to low was: NI > AI > SSD. It was probably supposed that the high activity of NI and AI was a main promoter for the accumulation of fructose and glucose in Chinese bayberry fruit at harvesting time. The activity of sucrose synthase ( synthesizing direction, SSS) and sucrose phosphate synthase ( SPS) changed differently in M. rubra cv. Dongkui fruits. Both of them reached their highest activity at full mature time, but the activity of SSS was higher than that of SPS. They were (53.4±2.4) and (35. 8 ±2.8) mg sucrose · g-1 FW, respectively. It probably implied that the high SSS and SPS activity was a main reason of sucrose accumulation in ripe red bayberry fruit, and SSS activity distributed more than that of SPS.%从开花后54 d起至果实成熟,对‘东魁’、‘黑晶’、‘温岭大梅’3个杨梅品种的果实发育动态、糖分积累和糖代谢有关酶的活性进行了研究.结果表明:成熟杨梅果实的糖分主要是蔗糖、果糖、葡萄糖,其中蔗糖含量最高,约为总糖分的40％～ 50％,其次是果糖和葡萄糖.糖分含量先小幅下降,然后快速积累,完全成熟时3种糖分均达到最高值,蔗糖、果糖、葡萄糖的含量分别为:34.4～48.9,24.6～28.6,23.2 ～27.7 mg·g-1鲜重.果实滴定酸含量则先上升,然后快速下降,成熟时降至最低点,为0.4％ ～0.6％.杨梅果实中与蔗糖代谢相关的中性转化酶(NI)、酸性转化酶(AI)、蔗糖合成酶分解方向(SSD)活性变化趋势相似,先下降,然后逐渐升高,成熟时达到最高,分别为:40.3 ～52.8,31.2～40.5,3.5 ～4.0 mg葡萄糖·g-1鲜重,活性从高到低顺序:NI＞ AI＞ SSD.表明成熟果实中较高的NI和AI活性可能是杨梅果实果糖和葡萄糖积累的主要动力.对‘东魁’果实的蔗糖合成酶合成方向(SSS)活性和蔗糖磷酸合成酶(SPS)进行测定,结果表明,随着果实成熟,两者均逐渐升高,但到果实成熟时活性均达到最高值,分别为:(53.4±2.4),(35.8 ±2.8)mg蔗糖·g-1鲜重,SSS的活性高于SPS活性,可能暗示SSS和SPS在成熟果实中的高活性是杨梅果实蔗糖积累的主要动力,SSS对蔗糖积累的贡献要大于SPS.
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