【作者】 闫素辉；

【导师】 王振林；

【作者基本信息】 山东农业大学 ， 作物栽培学与耕作学， 2009， 博士

【摘要】 本研究选用遗传性淀粉组分不同的小麦品种,通过改变小麦籽粒灌浆阶段温度,系统研究小麦籽粒淀粉粒度分布,直、支链淀粉合成与相关酶活性的变化,分析不同类型小麦籽粒淀粉粒分布、淀粉形成的差异,淀粉组成与淀粉粒度分布、相关酶活性的关系,明确高温对淀粉品质形成影响的生理生化机理。主要研究结果如下:1小麦胚乳淀粉的粒度分布特征1.1淀粉组分不同的小麦品种胚乳淀粉粒粒度度分布成熟期小麦籽粒中含有2种类型的淀粉粒,直径较小的B型淀粉粒(<10μm),和直径较大的A型淀粉粒(>10μm)。淀粉粒的粒径范围在0.3~45.0μm之间变化。淀粉粒的体积分布表现为双峰变化,峰值分别出现在5μm和21μm左右。小麦淀粉粒的数目分布表现为单峰分布,峰值出现在0.5~1μm,其中B型淀粉粒数目占总数目的99%以上,表明小麦籽粒中的淀粉粒大部分为小淀粉粒。小麦淀粉粒的表面积表现为双峰分布,峰值分别出现在1.5~2.8μm和21μm左右,B型淀粉粒的表面积占总表面积的80%左右,A型淀粉粒占20%左右。本研究将B型淀粉粒分为三组:小淀粉粒组(<0.8μm),中淀粉粒组(0.8~2.8μm),大淀粉粒组(2.8~10μm),其中<0.8μm的淀粉粒数目占总数目的34.9~55.5%;0.8~2.8μm的淀粉粒数目占总淀粉粒数目的40.4~63.3%;2.8~10μm的淀粉粒数目占总淀粉粒数目的2.9~6.3%(表1-2)。在三组参试品种中,糯小麦中<0.8μm的小淀粉粒组数目占总数目的百分比最低,高直链淀粉组和低直链淀粉组品种间无明显差异。0.8~2.8μm的中淀粉粒数目百分比,糯小麦最高,其它两组品种间无明显差异。2.8~10μm的大淀粉粒组占到总淀粉粒的比例较小,糯小麦的最高,低直链淀粉组品种最低,高直链淀粉组品种介于两组之间。说明直链淀粉含量影响淀粉粒的数目分布,其影响程度与淀粉粒粒径有关。在三组参试品种中,糯小麦B型淀粉粒体积和表面积百分比最高,其次为低直链淀粉组,最低的高直链淀粉组;高直链淀粉组的小麦胚乳中A型淀粉粒体积和表面积百分比最高,其次为低直链淀粉组,糯小麦最低。1.2小麦胚乳淀粉粒的发育动态花后4 d,小麦胚乳已出现不同范围大小的淀粉粒,最大直径8μm。花后7 d,淀粉粒增多增大,最大直径20μm左右。花后10~14 d,淀粉粒体积继续增大,并产生了一个新的小淀粉粒群体。花后17 d,淀粉粒以体积增大为主。花后21 d,淀粉粒最大粒径较成熟期变化较小。花后24 d,小于0.6μm的淀粉粒数目急剧增加,大于0.6μm的淀粉粒数目则明显减少,表明这一时期又产生了一个新淀粉粒群体(后期形成的B型淀粉粒)。花后24~28 d,小于0.6μm的淀粉粒数目仍不断增加,而直径较大的淀粉粒数目不断减少,表明籽粒中新淀粉粒的产生仍在继续,但增加幅度减少。花后28 d至成熟,主要是最小粒径淀粉粒生长,其它粒径淀粉粒直径的变化相对较小。2淀粉组分不同的小麦品种籽粒淀粉积累及相关酶活性变化研究结果表明,蔗糖合酶(SS)、腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)、束缚态淀粉合酶(GBSS)、可溶性淀粉合酶(SSS)和淀粉分支酶(SBE)活性均呈单峰曲线变化。高直链淀粉含量的小麦品种籽粒上述酶活性均显著高于低直链淀粉含量的小麦品种的淀粉合成相关酶活性。相关分析表明,支链淀粉积累速率与SS、AGPP、SSS和SBE呈显著或极显著正相关;直链淀粉积累速率与SS、AGPP和GBSS呈极显著正相关。Logistic方程拟合淀粉积累过程发现,支、直链淀粉最终积累量的高低取决于积累启动时间的早晚和积累速率的高低,而积累持续期的长短对支、直链淀粉最终积累量的调节作用较小。直链淀粉的积累速率除受GBSS活性的影响外,同时还受SS和AGPP活性的影响,其中,GBSS活性的变化与品种籽粒直链淀粉积累量的变化情况基本吻合。籽粒灌浆后期的GBSS活性对直链淀粉最终积累量的调节作用大于灌浆前期。3不同粒位籽粒淀粉积累及相关酶活性变化小麦强势粒直、支链淀粉积累量均高于弱势粒,密穗型小麦籽粒直、支链淀粉积累量在强、弱势粒间的差异幅度高于疏穗型小麦。Logistic方程拟合籽粒淀粉积累进程表明,强势粒淀粉积累量较弱势粒高的原因是其积累启动时间较早和淀粉积累速率较高;密穗型小麦强、弱势粒淀粉积累速率的差异幅度较大,是造成其最终淀粉积累量在强、弱势粒间的差异幅度大于疏穗型的原因之一。小麦强势粒胚乳细胞数目显著高于弱势粒,与疏穗型小麦相比,密穗型小麦强、弱势粒胚乳细胞数目的差异幅度较大。小麦品种弱势粒蔗糖含量在灌浆期均高于强势粒,说明籽粒蔗糖含量即淀粉合成底物的供给并不是造成强、弱势粒淀粉积累存在差异的限制因子。强势粒SS、AGPP、SSS和GBSS活性均高于弱势粒,密穗型小麦粒位间上述酶活性差异幅度均较疏穗型大。小麦库容量(胚乳细胞数目)和库活性(淀粉合成相关酶活性)是制约强、弱势粒淀粉积累的主要因素。密穗型小麦强、弱势粒间的胚乳细胞数目和淀粉合成相关酶活性差异较大,这可能是造成密穗型小麦籽粒淀粉积累量在强、弱势粒间的差异幅度大于疏穗型的原因。4高温对籽粒产量及淀粉品质形成的影响4.1高温对籽粒产量的影响本研究结果表明,灌浆期高温条件下,籽粒产量及其构成因素均受到了影响。不同时期高温处理均可降低籽粒产量、穂粒数和千粒重。不同时期高温对籽粒产量和粒重的影响程度表现为:T1<T2<T3。对穂粒数的影响表现为,灌浆前期高温处理后穂粒数较对照减少,中、后期高温对穂粒数无明显的影响。说明高温条件下,籽粒产量的下降主要是由于粒重下降引起的。不同小麦品种对高温的反应不同,耐热性较强的小麦品种籽粒千粒重、产量下降幅度较小,耐热性较差的小麦品种下降幅度较大。4.2高温对籽粒品质的影响高温对湿面筋含量、面团形成时间、面团温度时间的影响因时期而异。灌浆期高温处理后,湿面筋的含量均较对照提高,T1处理提高幅度最大,其次为T2、T3处理。T1、T2处理后,面团形成时间、面团温度时间较对照提高,T3处理后,面团形成时间、面团温度时间下降。T1、T2和T3处理后,高峰粘度、低谷粘度、衰减值、最终粘度和反弹值均较对照下降。T3处理对淀粉高峰粘度、低谷粘度等参数影响最大,其次是中期,前期影响最小。高温对糊化温度和峰值时间的影响较小。4.3高温对淀粉积累、粒度分布及组分含量的影响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,T3处理对籽粒淀粉积累的影响程度较T2、T1处理大。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。4.4高温对旗叶抗氧化酶活性的影响T1处理后,小麦旗叶、根系SOD活性均较对照有不同程度的提高,随着胁迫解除时间的延长,旗叶和根系SOD活性一直呈下降趋势。T2、T3处理后,旗叶和根系SOD活性均较对照降低。高温处理后,旗叶、根系POD活性均高于对照,CAT活性均较对照下降。花后旗叶、根系MDA含量随植株衰老逐渐增加。高温处理后,旗叶、根系MDA含量较对照显著上升,旗叶、根系可溶性蛋白含量较对照显著下降。说明高温处理提高了旗叶和根系的膜脂过氧化水平,加剧了小麦植株的衰老进程。4.5高温对淀粉合成相关酶活性的影响T1处理后,籽粒蔗糖含量、SS和AGPP、SSS、GBSS和SBE活性均略高于对照;随着解除胁迫时间的延长,上述指标分别于花后15 d、20 d开始低于对照。T2、T3处理后,籽粒蔗糖含量、SS、AGPP、SSS、GBSS和SBE活性显著低于对照。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。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。更多还原

【Abstract】 Wheat cultivars with different starch components inherently were grown at Tai’an Experimental Station of Shandong Agriculture University during the 2004~2008 growing seasons. The granule size distribution, starch synthesis, and related enzymes activities were roundly investigated, and the results elucidated the relationship between starch component and granule distribution, the relationship between starch component and related enzymes activities, the difference in starch granule size distribution and starch synthesis in different cultivars, and the physiological and chemical mechanism of high temperature effects on starch quality formation. The main results were as follows:1 The characteristics of starch granule size distribution in wheat endosperm1.1 The starch granule size distribution of wheat cultivars differing in amylose contentThe field experiments were carried out at Tai’an Experimental Station of Shandong Agricultural University in two growing seasons from October 2006 to June 2007 and from October 2007 to June 2008. Nine wheat cultivars (Triticum aestivum L.), YM 50, SN 1391 and SN 8355 (high amylose content in grains), and SN 12, JM 20, and SN 8355 (low amylose content in grains), and ANN1, ANN2 and LH9-8 (Waxy wheat) were employed in this study.The results indicated that there were two types of starch granules: smaller B-type granules (<10μm) and large A-type granules (>10μm) in wheat endosperm at maturity. The starch granules diameter changed in the range of 0.3~45μm. Volume distribution of starch granules showed the typical two populations with peak values in 5μm and 21μm, respectively. The number distribution exhibited a single peak curve with peak at 0.5~1μm. And B-type granule number comprised over 99% of the total starch granule numbers, indicating that the number of starch granules was mainly small starch granules. Similar to volume distribution, the surface area distribution also showed double peak curves with peak at 1.5~2.8μm and 21μm, and the B-type granules comprised about 80%, and A-type granules contributed about 20% of the total surface area.In the present study, the B type granules were divided to three classes, small starch granule (<0.8μm), middle starch granules (0.8~2.8μm) and big starch granules (2.8~10μm). The number of small granules account for 34.9~55.5% of total starch granules, the number of middle granules comprised about 40.4~63.3% of total starch granules, the number of big granules occupied 2.9~6.3% of total starch granules (Table 1-2). In three classes test cultivars, the Waxy wheat cultivars contained lowest number of small starch granules, and there was no difference in cultivars with high and low amylose content. The Waxy wheat cultivars had highest number of middle starch granules, and there was no difference in cultivars with high and low amylose content. The number of big starch granules was highest in Waxy wheat cultivars, the second was the cultivars with high amylose, and the third was the cultivars with low amylose content. The results suggested that the amylose content influenced the number distribution, the effect degree varied with the size of starch granules.The volume of B type granules was highest in the Waxy wheat cultivars followed by the cultivars with low amylose content, the cultivars with high amylose content was the lowest. The volume of A type granules was in order in cultivars with high amylose content > cultivars with low amylose content > Waxy wheat cultivars, which indicated that the amylose content affected the volume distribution of starch granules. Similar to volume distribution, the surface of B type granules was highest in Waxy wheat cultivars, the second was cultivars with low amylose, and the third was cultivars with high amylose.1.2 The dynamic changes of starch granules in wheat endospermThe number of starch granules in wheat endosperm exhibited single peak curves or double peak curves. The starch granules initiated at 4 DAA increased in size to a broad band of variously sized granules up to about 20μm diameter by 7 DAA. The diameter band of starch granules continued to grow up and a burst of synthesis created a new population of small starch granules by 10~14 DAA, which reduced the number proportion of big starch granules. At 17 DAA, starch granules in grain mainly increased in volume. At 24 DAA, the number of starch granules less than 0.6μm increased sharply and that more than 0.6μm reduced evidently, indicating that a new distinct class of small granules was synthesized at this stage, but the magnitude of increase reduced. At 21 DAA, the highest diameter of starch granule ceased basically. From 28 DAA to maturity (35 DAA), it is mainly the diameter enlargement of smallest granule, not the other granule.2 Activities of enzymes involved in starch synthesis and starch accumulation in grains of two wheat cultivars with different amylose contentTwo wheat cultivars, JM20 (lower amylose content in grains) and LM21 (higher amylose content in grains), which both carry three waxy subunits were employed in this study during the 2004~2005 growing season. The results indicated that the activities of sucrose syntheses (SS), adenosine diphosphorate glucose pyrophrylase (AGPP), soluble starch syntheses (SSS), granule-bound starch syntheses (GBSS) and starch branching enzyme (SBE) all changed in pattern of a single-peak curve during grain filling. The SS, AGPP, GBSS, SSS and SBE activities of cultivar, which had higher amylose content, were higher than those of cultivar, which had lower amylose content (Fig.2-1-A, Fig.2-2). The accumulation rate of amylopectin was significantly or very significantly correlated with the activities of SS, AGPP, SSS and SBE; and the accumulation rate of amylose was highly significantly correlated with the activities of SS, AGPP and GBSS. The accumulation courses of both amylopectin and amylose were well fitted by the Logistic Equation by relating amylopectin and amylose content against days after anthesis. The simulation parameters revealed that the higher content of amylopectin and amylose resulted from earlier initiating time and greater accumulation rate, but accumulation duration probably played a less important role (Table 2-1). The amylose content in grains was mainly determined by GBSS activity as well as the activities of SS and AGPP. The change of GBSS activity as reflected by expressed amount of waxy gene was closely associated with the accumulation rate of amylose, indicating that amylose content in grains was determined by GBSS activity, especially at late grain filling stage. 3 Comparison of starch accumulation and sink strength in superior and inferior grains between compact and loose spike wheat cultivarsTwo loose spike wheat cultivars, SN1391 and SN12, and two compact spike wheat cultivars, LM21and JM20, were chosen in this study during the 2005~2007 growing seasons. The results showed that the accumulation of amylose and amylopectin in superior grains were significantly higher than those in inferior grains in two spike type cultivars. But the magnitude of difference in amylose and amylopectin accumulation between superior and inferior grains in compact spike wheat cultivars was large relative to that in loose spike wheat cultivars. The accumulation courses of starch were well fitted to the logistic equation by relating starch contents against days after anthesis. Logistic simulation revealed that the higher starch accumulation in superior grains resulted from earlier initiating accumulation time and greater accumulation rate. There was a larger difference in starch accumulation rates between superior and inferior grains in compact spike wheat cultivars relative to that in loose spike wheat cultivars, which may be one of the reasons that caused a larger difference in starch accumulation between superior and inferior grains in compact spike wheat cultivars. Endosperm cell numbers in superior grains were significantly higher than those in inferior grains. The magnitude of difference in endosperm cell numbers between superior and inferior grains varied with cultivars, the greater difference was detected in compact spike cultivars, whereas smaller in loose spike cultivars. The sucrose content in superior grains was lower than those in inferior grains during grain filling, which indicated that the sucrose content (substrate of starch synthesis) may not be a main limiting factor for starch synthesis in inferior grain. The activities of enzymes involved in starch synthesis including SS, AGPP, SSS and GBSS in superior grains were significantly higher than those in inferior grains. The magnitude of difference in the above indexes between superior and inferior grains was larger in compact spike cultivars than that in loose spike cultivars. The results here suggested that grain sink strength, determined by both endosperm cell numbers and activities of enzymes involved in starch synthesis, was the main factor responsible for starch accumulation in wheat grain. The larger difference in the grain sink strength was found to result in larger difference in starch accumulation between superior and inferior grains in compact spike cultivars as compared with loose spike cultivars. 4 Effect of postanthesis high temperature on grain yield and starch quality formation of two wheat cultivars differing in heat tolerance4.1 Effect of postanthesis high temperature on grain yield and yield components of wheat cultivarsTwo contrasting winter wheat cultivars, JM20 (weak heat tolerance) and LM21 (strong heat tolerance) were used in this study during the 2004~2006 growing seasons. Three treatments of high temperature were made in the field with plastic sheds in the early (5~9 d after anthesis, T1), middle (15~19 d after anthesis, T2), and later grain filling (25~29 d after anthesis, T3), respectively, in comparison with the control plants that grew naturally.The results showed that there was significant effect of high temperature stress on grain yield and yield components of wheat. High temperature reduced grain yield, grain numbers per spike, and kernel weight, but not spike number, and the damage degree of high temperature on grain yield and kernel weight at later grain filling stages was higher than middle and early-filling stages. And high temperature at early grain filling stages reduced kernel number per spike, high temperature at middle and later-filling stages showed little effects on the kernel number per spike. The results suggested that the decrease of grain yield was result from the reduction of kernel weight under high temperature conditions. The conclusion also showed that there was a difference in reduction extent of grain yield and grain weight, the cultivar with weak heat tolerance had a larger reduction extent of grain yield and grain weight than those of cultivar with strong heat tolerance.4.2 Effect of postanthesis high temperature on grain quality of wheat cultivarsThere was difference in the response of farimograph index to high temperature among different stages. The wet gluten content increased after high temperature stress, and the increase variation of high temperature at early grain filling stages was highest, the second was middle-filling stages, and the third was the later-filling stages. After T1 and T2 treatments, the dough development time and the dough stability time increased significantly compared to control treatment, but decreased after T3 treatment.RVA parameters were influenced by high temperature, the peak viscosity, trough viscosity, break down, final viscosity, and set back decreased after T1, T2, and T3 treatments. The T3 treatment had the largerst damage on the peak viscosity, trough viscosity, break down, final viscosity, and set back, followed by T2 treatment and T1 treatment. High temperature had little effects on the pasting temperature and peak time.4.3 Effect of postanthesis high temperature on starch accumulation, starch component, and starch granule size distribution of wheat grainThe results showed that there was significant effect of high temperature stress on starch accumulation of wheat grain. High temperature remarkably reduced starch accumulation at 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 in the later period of grain filling had a larger effect on the starch accumulation than that in the middle and early grain filling. High temperature increased the volume, number and surface area of A type granule, but decreased the volume, number and surface area of B type granule, compared with control.4.4 Effect of postanthesis high temperature on antioxidant enzymes activities and lipid peroxidation of flag leaves and rootsAfter T1 treatment, the superoxide dismutase (SOD) activities of flag leaves and roots increased, with the time of stress released, the SOD activities of flag leaves and roots sharply decreased. After T2, T3 treatments, the SOD activities were reduced compared to control treatments. The peroxidase (POD) activities of flag leaves and roots in two cultivars significantly increased after high temperature. This indicated that there was difference in response to high temperature among different antioxidant enzymes. After high temperature stress, the catalase (CAT) activities of flag leaves and roots decreased compared to control treatment. The malondialdehyde (MDA) contents of flag leaves and roots increased gradually with the plant senescence. After T1, T2 and T3 treatments, the MDA contents of flag leaves and roots sharply increased relative to control treatment. And high temperature reduced the soluble protein contents in flag leaves and roots. The results suggested that high temperature increased the level of lipid peroxidation and accelerate the senescence of flag leaves and roots.4.5 Effect of postanthesis high temperature on enzymes involved in starch synthesis of grainAfter 5 d high temperature stress, the slight increases occurred in the sucrose content, the activities of SS, AGPP, SSS, GBSS and SBE in T1 treatment of two cultivars. But after removal of the high temperature stress in T1 treatment, the above parameters in wheat grains became lower than those of the control at both 15 d and 20 d. The significant decreases were observed in the sucrose content, SS, AGPP, SSS and SBE activities of T2 and T3 treatments. 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 that the difference between cultivars existed in tolerance to high temperature. Hence, it is suggested that growing cultivar with strong heat tolerance, 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.更多还原