【作者】 李旭；

【导师】 李学军；

【作者基本信息】 西北农林科技大学 ， 作物遗传育种， 2022， 硕士

【摘要】 随着经济发展和社会进步,人们对农产品、食品的需求已不仅仅停留在解决温饱、确保安全的阶段,而是有了更高要求,希望其集功能化、营养化、健康化于一体。目前,肥胖症与糖尿病已成为影响全球公众健康的重要问题,而高直链淀粉食品是肥胖和糖尿病人的理想食品,选育高直链淀粉小麦品种是当务之急。本研究对近年来黄淮麦区新育成284份小麦品种(系)的直链淀粉含量进行测定,从中选择4份直链淀粉含量差异较大的材料,研究其淀粉理化性质及消化特性,同时,分析其籽粒灌浆过程中淀粉合成相关基因的表达规律,主要研究结果如下:1、284份材料中有21份材料的直链淀粉含量低于20%,占全部材料的7.39%;有254份材料的直链淀粉含量介于20%～30%之间,占全部材料的89.44%;仅有9份材料的直链淀粉含量高于30%,占全部材料的3.17%。可见,本研究所选用的黄淮麦区现有小麦品种(系),高直链淀粉含量的小麦品种较少。2、选择4份直链淀粉含量差异较大的小麦材料,陕糯1号(3.66%)、郑麦119(20.31%)、中麦895(28.35%)和西农836(35.82%)。对4份材料淀粉理化性质的研究发现,B型淀粉粒含量与直链淀粉含量呈极显著正相关,且淀粉回生值以及凝胶强度均表现为:西农836>中麦895>郑麦119>陕糯1号;淀粉体外消化实验表明,西农836消化速率最慢,而陕糯1号消化速率最快。四个材料淀粉的总消化程度表现为:西农836(72.23%)<中麦895(74.23%)<郑麦119(76.34%)<陕糯1号(79.77%)。这说明直链淀粉含量的不同改变了淀粉的理化性质,并最终造成小麦淀粉在消化速率与消化程度上的差异。3、淀粉合成相关基因表达分析发现,在西农836中,颗粒结合淀粉合成酶基因GBSS Ⅰ的表达量在花后15天时急剧增加,一直维持在较高的水平,这可能促进了西农836中直链淀粉的合成。而淀粉去分支酶基因ISA Ⅱ在西农836整个灌浆期一直维持在较高的表达水平,表明该基因对直链淀粉的合成也具有一定的作用。综上所述,高直链淀粉小麦消化速率最慢,其功能不言而喻,然而黄淮麦区目前高直链小麦品种太少。从淀粉理化特性方面,简单易测的淀粉回生值可以作为高直链淀粉小麦选择的指标。在籽粒灌浆期,颗粒结合淀粉合成酶基因GBSS I、淀粉去分支酶基因ISA Ⅱ的表达量,也可以作为高直链淀粉小麦的筛选指标。本研究为高直链淀粉小麦品种的选育奠定了材料基础和方法依据。更多还原

【Abstract】 With the development of economic and social progress,people’s demand for agricultural products and food is no longer limited to solve the food problem and ensure food safety,but has higher requirements,hoping to integrate functional,nutritive and healthy products.At present,obesity and diabetes have become an important issue affecting global public health,and high amylose food is the ideal food for obese and diabetic patients,so the breeding of high amylose wheat varieties is a top priority.In this study,the amylose content of 284 wheat varieties was identified,and the effects of amylose content on the physicochemical properties and digestion characteristics of wheat starch were further studied,and the reasons for the difference in amylose content were analyzed from the expression of genes related to starch synthesis.The main results are as follows:1.By measuring the amylose content of 284 wheat varieties,it was found that the amylose content of 21 varieties was lower than 20%,the amylose content of 254 varieties was between20%and 30%,and the amylose content of only 9 varieties was higher than 30%.It can be seen that there are too few wheat varieties with high amylose content in the existing wheat varieties(lines)in Huang-Huai wheat region.2.The physicochemical properties and digestion characteristics of starch in four wheat varieties were studied.These four wheat varieties and their amylose content are Shannuo 1(3.66%),Zhengmai 119(20.31%),Zhongmai 895(28.35%),and Xinong 836(35.82%),respectively.It was found that the content of B-type starch granules was positively correlated with amylose content.The setback value and gel strength of starch are as follows:Xinong 836>Zhongmai 895>Zhengmai 119>Shannuo1;In vitro starch digestion experiments showed that the digestion rate of Xinong 836 was the slowest,while that of Shannuo 1 was the fastest.The total digestibility of starch of the four wheat starch was as follows:Xinong 836(72.23%)<Zhongmai 895(74.23%)<Zhengmai 119(76.34%)<Shannuo 1(79.77%).The results showed that the different amylose content changed the physicochemical properties of starch,and finally caused the difference in the digestion rate of wheat starch.3.By investigating the starch synthesis related genes expression patterns of four wheat varieties with different amylose content in the grain filling stage,found that the expression of GBSSⅠin Xinong 836 increased sharply at 15 day and then remained at a high level,which resulted in the higher amylose content in Xinong 836.And ISA Ⅱ genes in Xinong 836 has remained high expression during the grain filling stage,the results showed that the gene also played an auxiliary role in amylose synthesis.In conclusion,high amylose wheat has the slowest digestion rate and its function is self-evident.However,there are too few wheat varieties with high amylose content in Huang-Huai wheat region.In terms of physicochemical properties of starch,the setback value is easy to measure,which can be used as indexes for selecting wheat with high amylose content.The expression levels of GBSS Ⅰ and ISA Ⅱ at grain filling stage can also be used to identify the high amylose wheat.This study laid the material basis and method basis for the breeding of wheat varieties with high amylose content.更多还原