莲藕膨大过程中淀粉合成相关酶的活性变化及其与淀粉积累的关系

 【目的】研究莲藕根状茎膨大过程中淀粉合成相关酶的活性，探讨其与莲藕淀粉积累的关系。【方法】以4个莲藕主栽品种为试材，采用比色法，分析了根状茎膨大过程中葡萄糖、果糖、蔗糖、可溶性总糖、淀粉含量及腺苷二磷酸葡萄糖焦磷酸化酶（ADPGPase）、淀粉合成酶（SSase）和淀粉分支酶（Q-酶）活性的变化。【结果】果糖、葡萄糖和可溶性总糖、蔗糖的含量高峰分别出现在莲藕根茎的膨大前期、中期、后期。总淀粉、直链淀粉、支链淀粉含量在膨大中期前上升缓慢，到后期含量急增，总淀粉含量可达鲜重的11.1%～12.7%，其中支链淀粉始终约占总淀粉的70%。ADPGPase和SSase 在各相同膨大时期品种间差异明显，而Q-酶差异较小；3种酶表达上存在明显的时段特征，SSase表达最早，膨大前期即达峰值，ADPGPase和Q-酶活性的表达则相对较迟，均在中期达最大值；ADPGPase和SSase的活性峰值与后期总淀粉含量呈极显著和显著正相关，相关系数分别为0.9830（P＜0.01;n=12）和0.8458（P＜0.05;n=12）；Q-酶活性峰值与后期支链淀粉含量呈显著正相关，相关系数为0.7690（P＜0.05;n=12）。【结论】ADPG焦磷酸化酶和淀粉合成酶活性对成熟期莲藕根茎的总淀粉含量起关键调控作用；淀粉分支酶则调控根茎支链淀粉的含量。

Relationship of Starch Synthesis with It's Related Enzymes' Activities During Rhizome Development of Lotus(Nelumbo nucifera Gaertn)

With 4 lotus cultivars as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase (ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in rhizome during it development and their relationship with starch synthesis were studied. The results showed that peaks of fructose, glucose and total soluble sugar, sucrose content reached at beginning, middle, end stage of rhizome development, respectively. Total starch, amylose and amylopectin content in rhizome increased quickly after middle stage, total starch content reached 11.2% to 12.7% in fresh rhizome at end stage, and 70% of total starch was amylopectin. ADPGPase and SSase activities at the same development stage in different cultivar’s rhizome were obviously different, but Q-enzyme activity had little difference. During rhizome development SSase activity peak appeared earlier than ADPGPase and Q-enzyme at early stage, while ADPGPase and Q-enzyme activity peaks appeared at middle stage. ADPGPase activity at middle stage and SSase activity at early stage were very significantly and significantly correlated with total starch content at end stage in rhizome, co-efficient were 0.9830 and 0.8458,respectively; Q-enzyme activity was significantly correlated with amylopectin content at end stage, with co-efficient 0.7690.