作 者 ：闫素辉,尹燕枰,李文阳,李勇,梁太波,邬云海,耿庆辉,王振林
期 刊 ：生态学报 2008年 28卷 12期 页码：6138~6147
Keywords:winter wheat (Triticum aestivum L.), high temperature, starch, starch granule, enzyme activity,
摘 要 ：以耐热性不同的2个小麦品种济麦20和鲁麦21为材料，分别于花后5～9 d（T1）和15～19 d（T2）进行高温处理，研究了小麦花后不同阶段高温对籽粒淀粉积累、淀粉粒分布及相关酶活性的影响。结果表明，花后高温显著降低籽粒淀粉积累量；显著降低籽粒淀粉及支链淀粉含量，但提高直链淀粉含量、直/支链淀粉比例。处理间比较，T2处理对籽粒淀粉积累的影响程度较T1处理大。品种间比较，高温对济麦20的影响程度较鲁麦21大。高温使A型淀粉粒的体积、数量和表面积比例显著增加，B型淀粉粒的体积、数量和表面积比例显著降低。T1处理后，两品种籽粒蔗糖含量、蔗糖合酶（SS）和腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)、可溶性淀粉合酶（SSS）、束缚态淀粉合酶（GBSS）和淀粉分支酶（SBE）活性均略高于对照；但济麦20、鲁麦21上述指标分别于花后15、20 d开始低于对照。T2处理后，两品种籽粒蔗糖含量、SS、AGPP、SSS、GBSS和SBE活性显著低于对照，济麦20上述指标的降幅较鲁麦21大。与其它淀粉合成相关酶相比，高温对籽粒GBSS活性的影响程度较小。两品种处理间籽粒蔗糖含量、SS、AGPP、SSS、GBSS及SBE活性的变化趋势，与淀粉积累量的变化趋势基本一致。说明灌浆期高温使籽粒淀粉积累量降低，一方面是由于籽粒蔗糖供应较低引起糖源不足；另一方面则是由于灌浆中后期淀粉合成相关酶活性下降使淀粉合成受抑所致。
Abstract:Short period of high temperature stress, over 30℃, often happens during grain filling in many wheat production areas in the world, and has been an important factor limiting wheat grain yield and quality. Starch, a major component of wheat grain, has a close link with wheat grain yield and quality. It has been known that the grain starch accumulation reduces due to the high temperature during grain filling, leading to the decreased grain yield. However, there is little knowledge about how the formation of starch components, amylose and amylopectin, and the activity of the related enzymes change when wheat plants are exposed to high temperature stress during grain filling. The study was conducted to investigate the effects of high temperature at different periods of grain filling on grain starch formation of wheat. Two contrasting winter wheat (Triticum aestivum L.) cultivars, JM20 (weak heat tolerance) and LM21 (strong heat tolerance), were grown at Tai’an Experimental Station of Shandong Agriculture University during the 2004-2006 growing season. Two treatments of high temperature stress were made in the field with plastic sheds in the early (5-9d after anthesis, T1) and middle (15-19d after anthesis, T2) grain filling, respectively, in comparison with the control plants that grew naturally. The treatments were arranged in a randomized complete block design with three replications. Effects of high temperature stress at different grain filling periods in field on starch accumulation, starch granule distribution, and activities of the related enzymes were examined in developing grain of winter wheat. The results showed that there was significant effect of high temperature stress on grain starch accumulation. High temperature stress after anthesis remarkably reduced starch accumulation at the maturity. The total starch and amylopectin contents of high temperature treatments decreased markedly, but amylose content of heat treatments increased, as compared with control. Then the ratio of amylose to amylopectin in high temperature treatments was significantly higher than that of control. High temperature stress in the middle period of grain filling had a larger effect on the starch accumulation than that in the early grain filling. The starch accumulation of JM20 was decreased due to high temperature more than that of LM21, indicating that JM20 was more sensitive to high temperature. High temperature resulted in the significant increases of the volume, number and surface area percentage of A type granule, but the decrease of B type granule, compared with control. After 5d high temperature stress, the slight increases occurred in the sucrose content, the activities of sucrose synthase (SS), adnosine diphosphate glucose pyrophosphorylase (AGPP), soluble starch synthase (SSS), granule-bounded starch synthase (GBSS) and starch branching synthase (SBE) in T1 treatments of two cultivars. But after removal of the high temperature stress in T1 treatment, the above parameters in JM20 and LM21 became lower than those of the control at both 15d and 20d. The significant decreases were observed in the sucrose content, SS, AGPP, SSS and SBE activities of T2 treatments, especially in JM20 after 5d high temperature stress. However, only a little difference existed in GBSS activity between high temperature treatment and control. The grain starch accumulation was found in consonance with the grain sucrose content, and the activities of SS, AGPP, SSS, GBSS and SBE, suggesting that it was poor supply of sucrose and the decreased activities of the enzymes involved in starch synthesis that brought about the declined starch accumulation in grain under high temperature stress. As compared with LM21, JM20 had a larger decline in the starch accumulation and the activities of related enzymes, indicating the difference between cultivars existed in tolerance to high temperature. Hence, it is suggested in this paper that growing heat-resistant cultivars, and applying appropriate schedules of irrigation and fertilization would be effective to cut dawn the influence of high temperature stress during grain filling on wheat production.
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