【作者】 周琴；

【导师】 曹卫星；

【作者基本信息】 南京农业大学 ， 作物栽培学与耕作学， 2004， 博士

【摘要】 近年来，我国小麦产量不断提高，但品质未能同步改良，以致普通小麦生产过剩，而优质专用小麦需求迫切。因此深入研究不同品质类型小麦籽粒品质形成的生理机制及调控途径，对于深化小麦品质生理，促进小麦调优栽培具有重要意义。本文选用不同品质类型小麦品种为材料，综合研究了小麦碳氮物质运转和关键酶活性对小麦籽粒淀粉和蛋白质合成的影响，以及淀粉和蛋白质含量与品质指标的相互关系；并研究了源库平衡、供应源的碳氮比、以及外源糖氮物质供应对籽粒淀粉和蛋白质形成的调控作用，进一步明确了小麦籽粒品质形成的生理机制及调控途径。主要研究结果如下： 1．池栽条件下，以豫麦34、徐州26、扬麦10和扬麦9号四个不同专用小麦为材料，研究不同品质类型小麦籽粒淀粉和蛋白质积累动态及成熟期主要品质性状的相互关系。结果表明，小麦籽粒蛋白质含量表现为徐州26＞豫麦34＞扬麦10号＞扬麦9号，而淀粉含量則相反。清蛋白含量灌浆前期迅速下降，后期变化平缓，球蛋白灌浆前期下降，中后期逐渐回升，醇溶蛋白和麦谷蛋白则逐渐增加。灌浆中期开始，品种间清蛋白、球蛋白、醇溶蛋白和麦谷蛋白含量均与总蛋白含量变化趋势一致。直链淀粉含量逐渐上升，而支链淀粉含量与总淀粉变化趋势一致，前期上升迅速，后期增长缓慢。成熟期籽粒直链淀粉和支链淀粉含量均表现为扬麦9号＞扬麦10号＞豫麦34＞徐州26。相关分析表明，蛋白质含量与干面筋和湿面筋极显著正相关，而与其他品质指标相关不显著。谷蛋白／醇溶蛋白与面筋指数、沉淀值、降落值正相关，而与容重负相关。 2．以徐州26、扬麦10号和扬麦9号3个不同蛋白质含量的小麦基因型为材料，研究不同品质类型小麦籽粒蛋白质和淀粉积累特征与淀粉和蛋白质合成的关键酶活性关系。结果显示，光合作用强、旗叶磷酸蔗糖合成酶(SPS)活性高是扬麦9号籽粒淀粉含量高和产量高的重要原因之一。旗叶SPS活性和蔗糖含量变化趋势一致。籽粒中蔗糖合成酶(SS)活性高而蔗糖含量低，有利于蔗糖的迅速转化。籽粒淀粉合成酶活性高，淀粉含量也高。表明高淀粉含量品种不仅源供应能力强，库合成转化能力也强。旗叶和籽粒GS活性高有利于籽粒蛋白质合成。由此推测，籽粒淀粉和蛋白质合成途径中代谢关键酶的活性变化是籽粒淀粉和蛋白质含量差异的重要生理原因。营养器官中氮素转运量和蛋白质产量呈正相关，不同品质类型小麦籽粒淀粉和蛋白质形成的生理机理和调控途径而与蛋白质含量不相关，营养器官可溶性糖与氮素转运量的比值与籽粒蛋白质含量呈负相关，与淀粉含量呈正相关。因此，营养器官C、N积累与分配的相对差异可能是小麦籽粒蛋白质含量差异的重要原因之一。 3.池栽条件下，选用两个蛋白质含量不同的小麦品种，研究了剪叶剪彼来改变源库大小对小麦籽粒淀粉和蛋白质积累以及面粉品质的影响。结果表明，去穗和去旗叶处理降低了营养器官氮素和干物质积累量，但去旗叶处理促进了茎杆和穗壳中氮素和干物质转运量，而去穗处理则相反。去旗叶处理降低籽粒淀粉和蛋白质含量，去穗处理提高淀粉含量。去旗叶处理显著降低面筋含量，但提高了面筋指数和沉淀值，而去穗处理则相反。因此，改变源库比对籽粒品质形成有明显的调节作用。 4.离体条件下，采用恒定比例、不同浓度的蔗糖和谷氨酞胺培养液对扬麦9号和徐州26进行离体穗培养，研究了糖氮供应水平对小麦籽粒重、淀粉和蛋白质及其组分合成的影响。结果表明，单粒重、每穗粒重及每穗结实粒数随糖氮供应水平提高呈单峰曲线.旗叶SOD和CAT活性和粒重趋势一致，而MDA含量与粒重相反，可见不同的糖氮供应水平，离体穗生长状况不同。籽粒蔗糖含量随糖氮供应水平提高而上升，而淀粉含量则先上升再下降，直链淀粉和支链淀粉含量在碳氮浓度过高时显著下降。籽粒SS、555和GBSS活性与粒重和淀粉含量趋势一致，表明3种酶活性对籽粒淀粉合成有重要调节作用。籽粒中氨基酸、蛋白质含量随碳氮供应浓度的增加而逐渐增大.籽粒清蛋白和球蛋白随糖氮供应水平提高而上升，扬麦9号的醇溶蛋白高浓度时下降，两品种谷蛋白在高浓度处理时含量均下降。表明提高碳氮供应水平，可提高籽粒营养品质. 5.离体条件下，研究了谷氛酞胺供应水平对小麦籽粒重、淀粉和蛋白质合成及其组分含量的影响。结果表明，籽粒淀粉积累量和蛋白质积累量均随着培养基中谷氛酞胺供应水平提高，呈单峰曲线变化.随谷氨酞胺供应水平的提高籽粒蔗糖和淀粉含量逐渐下降，而氨基酸和蛋白质含量逐渐上升。籽粒直链淀粉和支链淀粉也随谷氨酸胺供应水平提高而下降.籽粒SS活性和粒重趋势一致，而555和GBSS活性则和淀粉含量趋势一致，呈逐渐下降趋势.籽粒中清蛋白和球蛋白随谷氨酞胺供应水平提高而上升，而醇溶蛋白和麦谷蛋白含量在一定浓度范围内呈上升趋势，过量供应则对籽粒醇溶蛋白和麦谷蛋白含量无明显影响。关键词:小麦;不同品质类型;籽粒蛋白质;籽粒淀粉;生理机制;调控途径更多还原

【Abstract】 In recent years, wheat grain yield has increased continuously, yet grain quality is not much improved. As a result, the ordinary type of wheat is overstock, while good quality wheat is of shortage and has to import from other countries. So elucidating the physiological mechanism and regulation principles for grain quality formation in wheat is of importance for understanding grain quality physiology and guiding cultural management for quality wheat production. In the present study, different wheat varieties with varied grain protein contents were used to investigate the impact of C and N assimilation, translocation and key regulatory enzyme activities on the formation of grain starch and protein, and the relationships between starch and protein contents and flour quality, to assess the regulating effect of source-sink alteration and varied sucrose and nitrogen supply levels on the formation of grain starch and protein, and further to establish the physiological mechanism and technical approaches for regulation of grain quality in specialty wheats’ The main results were summarized as follows:1. Four winter wheat cultivars differing in grain quality, Yumai 34, Xuzhou 26, Yangmai 10 and Yangmai 9 were used to determine the accumulation pattern of grain starch and protein contents and their components, along with flour quality traits. The results showed that grain protein content followed the order of Xuzhou 26>Yumai 34>Yangmai 10>Yangmai 9, while starch content was on the contrary. Albumin content decreased rapidly at the beginning stage and changed a little at later stage of grain filling. Globulin decreased initially and then increased until maturity. Gliadin and glutenin both increased with the progress of grain filling. From the mid stage of grain filling, the contents of albumin, globulin, gliadin, and glutenin also followed the order of Xuzhou 26>Yumai 34>Yangmai 10>Yangmai 9. Consistent with starch content, amylose and amypoctin increased gradually. The protein content was positively correlated to dry gluten and wet gluten significantly, and not correlated to other flour quality traits. Ratio of gliadin/glutenin was positively correlated to gluten index, SDS-sedimentation volume, falling number, while negatively correlated to test weight.2. Three wheat genotypes differing in grain protein content, Xuzhou 26, Yangmai 10 and Yangmai 9 were used to study the differences in grain protein and starch accumulation, and the ability of assimilate synthesis in flag leaves of different varieties. The results showed that Yangmai 9 had higher photosyntheitc rate, activity of sucrose phosphatesynthase (SPS) and sucrose content in flag leaf,than Yangmai 10 and Xuzhou 26. The activities of sucrose synthase (SS) in grain were also higher with Yangmai 9 than Yangmai 10 and Xuzhou 26, while the sucrose content was in a opposite pattern. Soluble starch synthase (SSS), granule bound starch synthase (GBSS) and starch content in wheat grain followed the order of Yangmai 9 >Yangmai 10> Xuzhou 26. Thus, higher starch content was not only linked to the ability of sucrose supply as source, but also to the higher catalytic ability of starch synthase in sink. The activity of glutamine synthase (GS) in flag leaf and grain were higher in Xuzhou 26 than those in yangmai 10 and Yangmai 9, consistent with grain protein content. These results indicated that grain starch and protein synthesis were closely associated with the activities of key regulatory enzymes. The ratio of transferred soluble sugar to nitrogen in vegetative organs was negatively correlated to grain protein content. Therefore, the differential patterns for accumulation and remobilization of carbon and nitrogen in vegetative organs could be one of the most important reasons for different grain protein contents.3. Two wheat varieties differing in grain protein content, Yangmai 9 and Xuzhou 26 were used to investigate the effects of spikelet- and leaf-removal on the accumulation of protein and starch and flour quality in wheat grain. Dry matter weight per stem and grain weight per更多还原