牛大力块根糖积累及其相关酶活性变化研究

Sugar accumulation and sucrose-metabolizing enzyme activities in tuberous roots of Callerya speciosa

关键词:  牛大力, 块根发育, 糖积累, 蔗糖代谢, 酶活性

Key words:  Callerya speciosa, tuberous root development, sugar accumulation, sucrose-metabolizing, enzyme activities

摘要:

为提高牛大力块根的产量与品质,该研究以不同发育时期(移栽6、12、18、24、30、36个月)的牛大力块根为材料,采用紫外分光光度法对糖类含量及其相关酶活性进行测定,研究它们在牛大力块根发育过程中的动态变化规律。结果表明:(1)牛大力块根的生长发育进程可初步划分为形成期(移栽6～12个月)、迅速膨大期(移栽12～24个月)与稳定膨大期(移栽24～36个月)三个阶段。淀粉与蔗糖分别是牛大力块根中主要的多糖与可溶性糖。在牛大力块根发育过程中,多糖类物质的含量逐渐增加,而可溶性糖含量逐渐减少,两者之间呈显著负相关,推测可溶性糖的分解代谢有利于促进多糖类物质的积累。(2)蔗糖的分解代谢是蔗糖合酶(SUS)、蔗糖磷酸合酶(SPS)、酸性转化酶(AI)与中性转化酶(NI)等多种相关酶协同作用的结果。SUS在牛大力块根发育过程中发挥着既催化蔗糖合成,又催化蔗糖分解的双重调节作用,SUS(合成)的活性不断上升,至移栽36个月达到峰值,极显著高于其他时期; SUS(分解)的活性从移栽6个月至24个月逐渐上升,但在块根稳定膨大期稍有下降; 其净活性为催化蔗糖分解,在移栽12个月达到最高。转化酶AI和NI的活性均在块根发育过程中逐渐上升,且AI活性高于NI活性,提示AI可能在蔗糖代谢分解过程中发挥更重要的作用。该研究结果可为今后深入研究牛大力多糖类成分积累和调控机制提供理论依据,并为提高牛大力药材的产量与品质提供技术指导。

Abstract:

In order to improve the yield and quality of Callerya speciosa, the dynamic variation rules of sugar accumulation and sucrose-metabolizing enzyme activities in tuberous roots at six different developmental stages(6, 12, 18, 24, 30, 36 months after transplanting)of C. speciosa were discussed using UV spectrophotometry methods. The results were as follows:(1)The root development can be preliminarily divided into three stages: the initial stage(from 6 to 12 months after transplanting), the rapid thickening stage(from 12 to 24 months after transplanting), and the stable thickening stage(from 24 to 36 months after transplanting). Starch and sugar were the main form of polysaccharides and soluble sugars in tuberous roots, respectively. The content of polysaccharides increased, whereas that of soluble sugars decreased during the tuberous root development. There was significantly negative correlation between polysaccharides and soluble sugars, suggesting that the decomposing of soluble sugars might facilitate to the accumulation of polysaccharides.(2)Several sucrose-metabolizing enzymes, such as sucrose synthase(SUS), sucrose phosphate synthase(SPS), acid invertase(AI)and neutral invertase(NI), played synergistic effects on metabolizing sucrose. SUS played a dual role in both synthesizing and decomposing of sucrose during the tuberous root development of C. speciosa. The activity of SUS(synthesizing)significantly increased along with root growth, peaked at 36 months after transplanting, whereas that of SUS(decomposing)increased from 6 months to 24 months after transplanting but decreased slightly at the stable thickening stage; the total activity of SUS played a role in the decomposing of sucrose and peaked at 12 months after transplanting. The activities of AI and NI increased consistently during the tuberous root development of C. speciosa. Moreover, the activity of AI was much higher than that of NI, indicating that AI might be more important in the decomposing of sucrose. These results provide a theoretical basis for the further study of regulation mechanism of polysaccharides accumulation, and provide technical guidance for the improvement of yield and quality in C. speciosa tuberous roots.