春性和半冬性小麦品质形成的根系形态生理特征及其对氮素的响应

Wheat root is not only the organ of absorbing the water and nutrient, but also the important synthesis place for a variety of hormones, organic acids and amino acid. The morphological and physiological characteristics have the close relationships with the shoot development, yield and quality. Nitrogen is one of the most important elements that affect root development and quality of wheat. In the past research, the significant difference in nitrogen utilization efficiency for the spring and semi-winter wheat were found. But people still don’t know the morphological and physiological characteristics of root resulting in the difference and the mechanism in response to nitrogen fertilizer.. The spring and semi-winter wheat cultivars were selected as materials in this study and nitrogen treatments were set. The structures of root and endosperm cells will be observed by the method of resin embedded and electron microscopy. The hormone content and enzyme activities related to root development will be determined. The study emphatically studies four aspects, as followed: (1) the difference of morphological and physiological characteristics of root between spring wheat and semi-winter wheat. (2) The effects of nitrogen on the morphological and physiological characteristics of root and the formation of quality for the two ecotypes. (3) The relationship between the morphological and physiological characteristics and quality formation for spring and semi-winter wheat. (4) Finding out the pathway to improve the quality of the two ecotypes wheat by regulating the morphological and physiological characteristics of root. There are research basis for this study. There are fresh ideas shine in the research content and research methods. The results of this study will not only enrich the theory system of crop physiology, cryobiology and sitiology, but also provide practical guidance for wheat breeding and cultivation .

小麦根系既是水分和养分吸收的主要器官，又是多种激素、有机酸和氨基酸合成的重要场所，其形态生理特性与地上部的生长发育及产量和品质关系密切。氮素是影响小麦根系生长发育和小麦品质最活跃的营养因子，博士阶段工作中发现，春性和半冬性小麦氮利用效率差异显著，但造成这种差异的根系形态生理特征和对氮素响应机理并不清楚。. 本项目拟以代表性春性和半冬性小麦品种为材料，设置不同氮素处理，采用电镜观察根系和胚乳发育、检测根系激素和酶活性等生理生化方法，着重研究：（1）春性和半冬性小麦根系形态生理的差异；（2）氮素对两种生态类型小麦根系形态生理及品质形成的影响；（3）春性和半冬性小麦根系形态生理与品质形成的关系；(4)找出适宜的春性和半冬性小麦品种的根系形态生理指标和氮素调控途径。项目研究有基础，研究内容有新意，研究结果既可丰富作物生理学、细胞生物学等学科的理论知识，又可为小麦育种、栽培提供理论指导。

氮素是小麦生长所必需的营养元素之一，干旱是小麦生产经常遇到的非生物胁迫因子，小麦根系作为水分和养分吸收的主要器官，其对氮素的吸收和对干旱的响应与颖果的发育密切相关，影响着小麦品质的形成。本项目以春性和半冬性小麦品种为材料，采取形态观测、显微和超微结构观察生理生化测定以及组学技术，着重研究了春性和半冬性小麦根系形态结构和胚乳蛋白体发育的特点及其对氮素和干旱的响应，揭示了根系生长与品质形成的关系，取得了以下重要和新颖的结果：.1. 探明了春性和半冬性小麦根系形态结构和胚乳蛋白体发育的差异.（1）春性和半冬性小麦根系发育存在差异，半冬性小麦根系短，侧根多，根尖的根冠区长，根横截面的维管束面积大。.（2）小麦胚乳蛋白体在早期主要通过蛋白质贮藏液泡形成，而在后期主要通过粗糙内质网衍生形成。.（3）半冬性小麦胚乳蛋白体积累显著高于春性小麦，这种差异在胚乳近糊粉层区域尤为明显。.2. 探明了氮素对春性和半冬性小麦根系生长及胚乳蛋白体发育的影响.（1）氮素处理促进了小麦苗期初生根的伸长和生物量的积累，并且半冬性小麦根系对氮素的响应程度比春性小麦大。.（2）施氮显著提高了小麦胚乳蛋白体的积累量，半冬性小麦的响应程度要大于春性小麦。.（3）施氮改变了小麦的加工品质，并且对半冬性小麦的影响更显著。.3. 探明了干旱对春性和半冬性小麦根系生长及胚乳蛋白体发育的影响.（1）干旱处理提高了小麦幼苗根系中氮转运蛋白的表达，促进了根系生长和氮吸收。.（2）干旱提高了小麦胚乳蛋白体的积累，春性和半冬性小麦胚乳蛋白体发育对干旱的响应程度存在差异。.（3）干旱胁迫下颖果中差异表达的miRNA参与调控了贮藏蛋白合成相关靶基因。.以上结果不仅能深化小麦籽粒品质形成机理的研究，而且为小麦品质改良的氮素调控和抗旱育种提供了理论依据。.本项目完成了预期目标和任务：发表学术论文8篇，其中被SCI收录4篇；培养硕士生7人；参加国内外学术会议6次。