不同水稻品种支链淀粉结构的差异及其与淀粉理化特性的关系

Difference of Amylopectin Structure among Various Rice Genotypes Differing in Grain Qualities and Its Relation to Starch Physicochemical Properties

利用改进的基于DNA测序仪的荧光糖电泳法对我国不同品质类型水稻品种和部分外引水稻品种的支链淀粉链长分布特征进行了测定,在尽量排除直链淀粉含量(amylose content,AC)对淀粉理化特性影响的基础上,分析了支链淀粉结构与稻米淀粉理化特性的相关性。结果表明,根据∑DP≤11/∑DP≤24的链长比值,可将50个供试品种的支链淀粉分为I型和II型两种结构类型,I型支链淀粉的链长比值小于0.22,II型支链淀粉的链长比值大于0.26。15个粳稻品种的支链淀粉结构属II型,35个籼稻品种中有15个品种的支链淀粉结构属I型,20个品种属II型。相关分析结果表明,∑DP6～11和链长比值与起始成糊温度(pasting temperature,PT)和相对结晶度(relative crystallinity,RC)呈极显著负相关;∑DP28～34与PT呈极显著负相关,与RC的相关性不显著;∑DP13～24和∑DP39～49与PT呈极显著正相关,与RC呈显著正相关。在糯稻、低AC和高AC品种中,∑DP6～11、∑DP13～24和链长比值与PT的相关性与在全部品种中的相关性一致,与RC的相关性也与全部品种中的相关性基本一致。∑DP28～34与PT在低AC品种中,∑DP39～49与PT在糯稻和高AC品种中、与RC在高AC品种中的相关性也与全部品种中的相关性具有一致性。不同链长范围的支链数量比例与GC(gel consistency)和RVA谱特征值的相关性基本不显著。可见支链淀粉不同链长范围的支链数量比例主要与淀粉的PT和RC相关,而与淀粉的GC和RVA谱特征值关系不密切。

As the main constituent of rice starch, amylopectin and its structure is one of the major determinants for the development of starch granule structures and starch physicochemical properties. Understanding amylopectin chain length distribution properties in different rice varieties, and clarifying the correlations between the amylopectin structure and rice starch physicochemical properties, may provide theoretical basis for revealing the mechanism of rice quality development and guide rice quality improvement. In this study, the amylopectin structure of some rice varieties in China and some introduced rice varieties with different qualities were characterized by improved fluorophore-assisted carbohydrate electrophoresis （FACE） method based on DNA sequencer. On the basis of eliminating the impact of amylose content （AC）, the correlations between amylopectin structure and rice starch physical chemistry properties were analyzed. The results indicated that amylopectin structure in 50 rice varieties could be classified into Ⅰ-type and Ⅱ-type, according to the chain ratio of ∑DP≤ 11/∑DP〈24. The chain ratio of the Ⅰ-type amylopectin is less than 0.22, whereas the Ⅱ-type is higher than 0.26. Amylopectin of all the 15 japonica varieties belonged to Ⅱ-type. Among the 35 indica varieties, for amylopectin structure, 15 belonged to Ⅰ-type and 20 belonged to Ⅱ-type. The EDP6-11 and chain ratio had very significantly negative correlations （P〈0.01） with pasting temperature （PT） and relative crystallinity （RC）. The ∑DP28-34 had very significantly negative correlation with PT, but did not have significantly correlation with RC. The ∑DP13-24 and ∑DP39-49 had very significantly positive correlations with PT and significantly positive correlations （P〈0.05） with RC. In glutinous rice, low AC and high AC varieties, the correlations of ∑DP6-11, ∑DP28-34, the chain ratio of∑DP≤11/∑DP≤24 with PT and RC were essentially consistent with those in all varieties. The correlations between ∑DP28-34 and PT in low AC, between ∑DP39-49 and PT in glutinous rice and high AC varieties, between ∑DP39-49 and RC in high AC varieties were also consistent with those in all varieties. The proportion of chain amounts in amylopectin with different chain length ranges was not significantly correlated with GC and RVA profile properties. Therefore, the proportion of chain amounts in amylopectin with different chain length ranges has relation to rice starch PT and RC, but not close relation to GC and RVA profile characteristics in most cases. The short chain amounts of DP6-11 have a ftmction of decreasing rice starch PT and RC, the intermediate chain amounts of DP 13-24 have a function of increasing rice starch PT and PC, the longer chain amounts of DP 28-34 have a function of decreasing rice starch PT and the long chain amounts of DP 39-49 have a function of increasing rice starch PT and RC.