枣不同品种和果实不同部位糖积累及相关酶活性

Sugar Accumulation and the Relevant Enzymes Activities in Different Parts of Fruit of Three Jujube Cultivars

【目的】本文旨在揭示不同的枣品种生长发育过程中果实不同部位糖积累特征及其与糖代谢相关的酶活性的关系,为进一步完善枣果实糖积累理论提供依据。【方法】以3个枣品种壶瓶枣、婆婆枣、婆枣为研究对象,利用高效液相色谱等技术测定不同发育时期枣果实果肩与果顶部位的蔗糖、果糖、葡萄糖、淀粉含量及相关酶活性的变化。【结果】1)3个枣品种果肩部位糖积累均早于果顶,且果肩可溶性糖含量均显著高于果顶(P<0.05)。在果实发育前期主要积累果糖和葡萄糖,壶瓶枣果实最早开始积累蔗糖,成熟时其含量为果糖和葡萄糖的3~4倍;其次是婆婆枣,其糖积累模式与壶瓶枣相似;婆枣果实糖积累发生最晚,其果糖和葡萄糖含量远高于蔗糖。成熟时婆婆枣果实可溶性总糖含量极显著高于壶瓶枣和婆枣(P<0.01)。2)整个果实发育阶段,3个枣品种果实淀粉含量均较低(最高值为6.78 mg·g^(-1)FW),且果肩部位淀粉含量均低于果顶,淀粉酶活性的变化基本与其淀粉含量的变化趋势相反。3)3个品种果肩与果顶部位蔗糖代谢酶活性变化规律相似;在整个阶段,酸性转化酶(AI)活性始终高于中性转化酶(NI),果实发育前期较高活性的转化酶促进了蔗糖的分解;蔗糖磷酸合成酶(SPS)活性变化与3个品种的蔗糖含量差异及变化趋势均相符;婆婆枣和壶瓶枣蔗糖合成酶的合成方向(SSs)活性分别极显著和显著的高于婆枣,3个品种蔗糖合成酶的分解方向(SSd)活性均较低,品种间无显著差异。【结论】壶瓶枣和婆婆枣为典型的蔗糖积累型果实,婆枣为己糖积累型果实;SPS是调控婆婆枣同时也是影响3个枣品种果实蔗糖积累的共同关键酶,可能也是引起不同枣品种果实糖含量差异的主要原因,枣果实中蔗糖合成酶活性以合成方向为主,壶瓶枣果实糖积累受蔗糖代谢相关酶的综合调控,婆枣果实糖积累还受SSd调控。淀粉酶在3个品种枣果实淀粉积累过程中起着主要调控作用。

【Objective】 【Objective】The objective of the present study was to reveal the relationship between sugar accumulation and the activity of sucrose-metabolizing enzymes in different Jujube cultivars and different parts of fruits at different developmental stages so as to provide a basis for further improving the sugar accumulation theory in jujube fruits.【Method】The fruits from three different cultivars,Ziziphus jujuba‘Hupingzao＇,Z.jujuba ‘Popozao＇,and Z.jujuba‘Pozao＇,were used to determine the content of sucrose,fructose,glucose,starch and the relevant metabolizing enzyme activities in the shoulder and top part of jujube dates at different developmental stages with High Performance Liquid Chromatography（HPLC）.【Result】1） The sugar accumulation started a little earlier in shoulder part than in top part of dates of all three jujube cultivars.The content of soluble sugar in the fruit shoulder was significantly higher than that in the fruit top in all three jujube cultivars（P〈 0.05）.Both fructose and glucose were mainly accumulated at early stage of fruit development,and the content of sucrose was very low in all tested cultivars.Cultivar ‘Hupingzao ＇ firstly began to accumulate sucrose,and the content of sucrose reached to 3-4 times greater than that of fructose and glucose at maturity.As for cultivar ‘Popozao ＇,the sugar accumulation pattern was similar to that of ‘Hupingzao ＇,while the sucrose accumulation in ‘Pozao ＇ was lastly occurred,and the content of fructose and glucose was much higher than that of sucrose.The soluble sugar content of ‘Popozao＇was significantly higher than ‘Hupingzao＇and ‘Pozao＇at fruit ripening stage（P 0.01）.2） The starch content of jujube fruits in all three cultivars was low over the whole developmental stage（the highest value was 6.78 mg·g-1 FW）,and it was lower in shoulder than in top part.The activity of amylase in three cultivars showed opposite trend to that of starch accumulation throughout the process.3） The metabolizing enzymes of sugar in stem end showed similar activities to that in calyx end in all three cultivars.The acid invertase（AI） activity was always higher than that of neutral invertase（NI）.Highly active invertase promoted the metabolism of sucrose at the early stage of fruit development.The activity variation of sucrose phosphate synthase（SPS） was consistent with the change of sucrose accumulation in all varieties.The activities of sucrose synthase in direction of synthetic（SSs） in ‘Popozao＇and‘Hupingzao＇were significantly higher than ‘Pozao＇.The sucrose synthase activity in direction of cleavage（SSd） in three cultivars was low,and no significant difference was detected among different cultivars.【Conclusion】The jujubes of‘Hupingzao＇and‘Popozao＇were typically sucrose accumulated fruits,while‘Pozao＇jujube was hexose-prevalent type.SPS regulated sugar accumulation in ‘Popozao ＇fruits,and was also the common key enzyme to control fruit sucrose accumulation of all three cultivars,therefore it could be the main factor of different content of soluble sugar in different cultivars.The sucrose synthase（SSs） enzyme played a key role mainly in the synthetic direction during the course of fruit development.The fruit sugar accumulation of ‘Hupingzao ＇ was regulated comprehensively by sucrose metabolizing enzymes.Sugar accumulation in ‘Pozao＇fruit was regulated by both SSd and SPS,and amylase played an important role in the starch accumulation in jujube fruits for all three cultivars.