苹果果实糖积累特性与品质形成的关系

Relationship between the Characteristics of Sugar Accumulation and Fruit Quality in Apple(Malus domestica Borkh.) Fruit

以富士和国光苹果为研究对象,对其果实发育过程中糖含量及其代谢关键酶活性的变化进行测定分析,以揭示糖分积累代谢特性对果实品质形成的影响.结果表明:(1)富士和国光均为己糖积累型果实,富士果实以积累果糖最多,果糖/葡萄糖(F/G)值为1.56,而国光以积累葡萄糖最多,F/G值仅为0.68;蔗糖在两品种中含量和所占比例均很低,在近成熟期富士高于国光.(2)富士果实蔗糖磷酸合成酶(SPS)和蔗糖合成酶(SS)活性均随果实糖的累积量增加而显著升高,酸性转化酶(AI)活性也渐趋升高,而中性转化酶(NI)活性波动不大,且其糖累积与AI和SPS活性相关性最大,而与NI相关性不大,SS的作用主要表现在发育后期;在国光果实糖积累过程中SPS起主导作用,SS和NI的作用主要表现在发育前期,而AI的作用不大.(3)富士和国光果实淀粉含量变化趋势相同,在淀粉积累高峰之后,富士果实淀粉降解速度更快,其淀粉含量迅速下降且低于国光,此时其相应淀粉酶活性也高于国光.研究发现,富士和国光果实糖积累和淀粉代谢均存在显著差异,从而直接或间接地影响着果实糖代谢过程,进而导致果实品质的显著差异.

The fruits of two apple cultivars, ＇ Fuji＇ and ＇Ralls＇, were used as materials to understand the effect of sugar accumulation and their metabolism on quality formation during fruit development. The resuits indicated that. （1） The fruit of two apple cultivars mainly accumulated hexoses （fructose and glucose） ,but there was significant difference in the sugar content and their proportion. During fruit development,the fructose accounted for the most proportion of soluble sugar in ＇Fuji＇,the ratio of fructose and glucose （F/G） was 1. 56. However, the highest soluble sugar in ＇Ralls＇ was glucose, its F/G was only 0.68, no more than half of ＇Fuji＇. The contents of sucrose were at very low levels in both ＇Fuji＇ and ＇Ralls＇. （2）The activities of sucrose phosphate synthase （SPS） and sucrose synthase （SS） increased rapidly,while acid invertase （AI） activity increased slowly with soluble sugar accumulation in ＇Fuji＇ apple,and the neutral invertase （NI） changed little. The analysis of correlation indicated that AI and SPS were most significantly related to sugar accumulation in ＇Fuji＇ apple,and the role of SS mainly showed in late stage, no relation with NI. However,SPS had main role in sugar accumulation,and the roles of SS and NI mainly occurred in early stage. （3）The change of starch had a similar rule in both ＇Fuji＇ and ＇Ralls＇. Their difference mainly occurred in late stage. After peaks of starch content,its degradation rate in ＇Fuji＇ was faster and its content was lower than that of ＇Ralls＇. Meanwhile,the amylase activity in ＇Fuji＇ was also higher than that in ＇Ralls＇. In the whole,there was remarkable difference in the sugars accumulation and starch degradation between ＇Fuji＇ and ＇Rails＇, which directly or indirectly affected on fruit quality formation through their different sugar metabolism.