灌浆结实期不同温度下早籼稻米淀粉链长分布与结构特征差异分析

Differences in Starch Chain Length Distribution and Structure Characteristics of Early-indica Rice Under Different Temperature Treatments During Grain-filling

利用人工气候箱设高温(32℃)和适温(22℃)两个典型温度处理,对4个早籼水稻品种在不同灌浆结实期温度下的淀粉链长特征与晶体结构差异进行了分析。结果表明,高温处理下稻米淀粉的长B链(FrII-1)的比例明显下降,其平均分子聚合度也有所减小,而中等B链(FrII-2)的比例则有所上升,其余淀粉组分的比例及其平均分子聚合度在不同温度处理下的变化规律则不明显,可能与品种本身的淀粉类型特性有关;对不同温度处理后淀粉的X-衍射图谱分析表明,灌浆结实期的不同温度处理并不影响稻米淀粉的晶体类型,但对淀粉的微晶结构有着一定影响,高温处理下X-衍射图谱中的182θ峰相对较高、172θ峰相对较低,其变化与稻米淀粉中的长B链含量呈显著负相关,而与中等B链含量呈正相关。

Effects of temperature during grain-filling on chain length distribution and structure characteristics of 4 early-seasonindica rice cultivars were investigated under the environment-controlled conditions. The plants at flowering stage weresubjected to two temperature treatments until maturity (the mean dairy air temperature, 22 and 32C for optimum temperaturetreatment and high temperature treatment, respectively). The result showed that high temperature during grain-fillingsignificantly decreased the long B-chain content and increased the intermediate B-chain content. But the effect of hightemperature on other starch chains appeared to be cultivar-dependant. The crystalline characteristics of rice starch werealso affected by temperature during grain-filling. The intensity at 18 2q of X-ray diffraction pattern of rice samples underhigh temperature was higher than those under optimum temperature, though all rice starches performed A-crystallinetype. Moreover, the intensity at 18 2q was positive correlation with intermediate B-chain content and negative correlationwith long B-chain content.