【作者】 李培英；

【导师】 朱进忠；

【作者基本信息】 新疆农业大学 ， 草业科学， 2010， 博士

【摘要】 偃麦草(Elytrigia repens (L.) Nevski)隶属禾本科偃麦草属,多年生草本,具发达的根茎,侵占性强,抗寒、耐踏、耐荫、耐湿、较耐旱,轻度盐渍化土壤亦能生长,且具较高营养价值,是一种具有潜在开发价值的优良草坪草、牧草资源。新疆是偃麦草资源的一个主要分布区,本文在对新疆野生偃麦草资源调查收集的基础上,以采集的39份野生偃麦草和5份引进偃麦草为供试材料,对其形态特征、抗旱性(包括种子萌发期、幼苗期抗旱评价及其生理响应)、坪用性、遗传差异(包括同工酶和DNA分子水平)等进行评价,筛选抗旱性好及坪用性优的优良居群,进而了解不同居群在分子水平的遗传差异程度,为资源有效保护与开发利用、品种选育工作中亲本的选配提供科学依据。主要研究结果包括:(1)对41份偃麦草种质资源的16个形态性状指标分析表明,偃麦草种内各形态指标存在较大的变异,变异系数介于4.88%-33.30%,其中叶层高度、旗叶长变异较大,而种子和颖片形态变异非常小。在相关分析结合主成分分析基础上,筛选出小穗数、百粒重、穗下第一节间长、叶长、叶层高度5个指标作为形态分异主要性状指标,将供试偃麦草材料划分为4大类,即高大型、偏高大型、特殊型、低矮型,其中特殊型、低矮型有望通过系统选育的方法,获得坪用性好的优良株系。(2)种子萌发期PEG模拟干旱胁迫结果表明,胁迫降低了偃麦草种质资源的发芽率、发芽势、发芽指数、发芽活力指数,抑制了胚芽和胚根的生长发育。采用隶属函数法,以相对发芽率、相对发芽势、相对胚芽长、相对胚根长、相对种子活力、相对发芽指数、萌发抗旱指数、胁迫指数为综合评价指标,得出29份偃麦草材料的抗旱能力由强到弱的次序为E39 > E14 > E11 > E13 > E16 > E03 >E07 > E25 > E34 > E42 > E09 > E29 > E17 > E31 > E21 > E26 > E06 > E10 > E12 > E27 > E38 > E08 > E01 > E04 > E41 >E19 > E37 > E02 > E24。(3)采用隶属函数法,以水分饱和亏缺、水分散失率、相对电导率、可溶性糖、土壤含水量为指标,对20份处于幼苗期的偃麦草材料进行抗旱性评价,其抗旱能力的次序为E01﹥E14﹥E13﹥E15﹥E17﹥E20﹥E09﹥E16﹥E19﹥E08﹥E18﹥E12﹥E07﹥E04﹥E10﹥E03﹥E06﹥E11﹥E02﹥E05,其中来自乌鲁木齐市永丰乡的2份材料E01与E13表现出较强的抗旱性,可为抗旱新品系选育提供材料。(4)依据苗期抗旱筛选,并结合田间观测结果,对4份抗旱能力不同的偃麦草材料E01、E05、E16、E22进行抗旱生理响应研究。结果表明干旱胁迫过程中偃麦草叶片水分饱和亏缺、电导率、丙二醛含量、脯氨酸含量呈现上升趋势,SOD活性及可溶性蛋白含量呈现先升高后降低趋势,而POD活性则表现降低趋势。与其他材料相比,抗旱性强的材料E01水分饱和亏缺值上升慢、增加率低,SOD酶活性峰值出现时间晚但峰值最高,可溶性蛋白含量变化小,脯氨酸积累少,MDA积累慢、含量低。(5)利用灰色关联分析的方法,以密度、盖度、抗旱性、出苗时间、成坪时间为指标对20份偃麦草材料的幼坪成坪性能进行评价表明,E11、E18与理想材料的关联度最大,其建坪性能最优,可以作为进一步选育优良草坪草的亲本材料利用;参照“景观-性能-应用适合度”与“外观-生态-使用”综合评价体系对偃麦草坪用性能进行评价表明,E18坪用性能最高,材料E04、E08、E09位于其后,也具有一定的育种价值。综合幼坪成坪性能与成坪坪用价值分析,认为E18、E04、E08可作为草坪用育种材料的首选。(6)对32份材料进行POD和EST同工酶分析表明:2种同工酶共出现16条酶带,其中10条酶带出现的频率较高,说明其种内分异较小,具有一定的同源性。以2种同工酶谱为基础,依据Jaccard相似系数,采用UPGMA方法将32份偃麦草材料划分为4大类,其中第一大类材料均来自新疆阿勒泰地区,表现出遗传特征与地域环境之间存在一定的相关性。(7)对32份偃麦草材料进行RAPD扩增表明,18条引物共扩增出264条带,多态性条带比例为93.7%,说明供试材料之间在DNA分子水平上多态性较高,表现出较丰富的遗传变异;以RAPD扩增结果进行聚类分析,在相似系数为0.373处,可将供试偃麦草种质资源划分为5大类群,且归类具有一定的地域相关性。(8)通过对新疆野生偃麦草资源形态特征、抗旱性、坪用性、分子水平遗传差异进行研究,发现居群间在不同性状上存在较大的变异,在遗传上存在丰富的遗传变异,有开发利用的潜能。筛选出的强抗旱居群和优坪用性居群,可为偃麦草新品系的选育奠定物质基础。更多还原

【Abstract】 Elytrigia repens (L.) Nevski,the perennial grass of Elytrigia genus of Gramineae, had potential value utilized for good turfgrass and forage, which had plenty of rhizome, strong spreading ability, and good cold-resistance, anti-trample capacity, shade tolerance, humidity resistance and drought resistance. At the same time, Elytrigia repens could be planted on light salt soil and had abundant nutrition value. Xinjiang was a main distributing area of Elytrigia repens in China. On the base of investigating and collecting wild Elytrigia repens germplasm resource in Xinjiang, five introduced materials and thirty-nine native materials in Xinjiang were studied about morphological characteristics, drought resistance (including appraising drought resistance of seed germinating period and seedling period, and response to the droght stress), turf-using characteristic and genetic diversity (including isozyme of EST&POD and DNA by RAPD), which could select good drought-resistance and turf-using materials, understand genetic variation among different materials and provide scientific basis for effective protection and exploitation of germplasm resource, parent selecting in breeding research. The mainly results showed:(1)The morphological characteristics analysis of 16 morphological indexes of 41 E. repens materials showed that the variation of morphological indexes was great among the materials, and the coefficient of variation of morphological indexes were from 4.88% to 33.30%. The variation of the leave level height and the length of flag leaf was great, and that of seed and glumes shape was little. Based on correlation analysis and principal component analysis, five morphological indexes, including number of spikelet, weight of 100 grains, the first node length under the spikelet, leave length, leave level height, were selected as main variation indexes of E.repens, and in according to five indexes, E.repens could be divided into 4 morphological types, including high type, partial high type, special type and dwarf type by cluster analysis, and special type and dwarf type of E.repens could be bred good turfgrass by traditional breeding method.(2) The drought resistance evaluation of E. repens materials in the period of seed germination under PEG stress showed that the germination rate, germination energy, germination index and vitality index of E. repens decreased, and the length of embryonic bud and embryonic root also decreased under PEG stress. According to the comprehensive evaluation of drought tolerance, with the relative germination energy, relative germination rate, relative vitality index, relative embryonic bud length, relative embryonic root length, germination drought-resistance index and germination stress index as evaluation indexes, by membership function method, the sequence of drought resistance of 29 E. repens materials from high to low was E39 > E14 > E11 > E13 > E16 > E03 > E07 > E25 > E34 > E42 > E09 > E29 > E17 > E31 > E21 > E26 > E06 > E10 > E12 > E27 > E38 > E08 > E01 > E04 > E41 >E19 > E37 > E02 > E24。(3) Through measuring the leaf water saturation deficit, water loss rate, electrical conductivity, soluble sugar content and soil water content under drought stress,the drought resistance of 20 E. repens materials was comprehensively evaluated in the seedling period with membership function method. The result showed that the sequence of drought resistance of 20 E. repens materials was E01﹥E14﹥E13﹥E15﹥E17﹥E20﹥E09﹥E16﹥E19﹥E08﹥E18﹥E12﹥E07﹥E04﹥E10﹥E03﹥E06﹥E11﹥E02﹥E05. E01 and E13 collected from yongfeng village, Urumqi in Xinjiang, appeared stronger drought resistance, and could be used in breeding materials of drought resistance.(4) According to the results of drought resistance evaluation in seedling period and observation in the field, four E. repens materials of different drought resistance were selected, including E01、E05、E16、E22, and their physiological response to water stress was studied. The results showed that leaf water saturation deficit(WSD), electrical conductivity(EC), malondialdephyde (MDA )content, proline (Pro) content of E. repens during the drought stress always increased, superoxide dismutasethe (SOD) activity and content of soluble protein showed the tendency firstly decreasing then increasing, and peroxidase ( POD) activity decreased. Compared with other materials, E01 with high drought resistance showed the tendency that WSD increased slowly and the value was low, the maximum value of activities of SOD delayed and had the highest SOD activities, the soluble protein changed little, proline increased little and had a lower MDA content.(5) By grey analysis method, with density, coverage, drought resistance, seedling emergencing time and turf-establishing time as evaluation indexes, evaluation on turf-establishing performance of 20 accesions was carried out. The result showed E11 and E18 had high correlation degree, excellent turf -establishing performance, as were worth being further exploited. Based on the comprehensive assessment system of landscap-performance-utilization and landscape-zoology–utilization,evaluation on the turf-using performance of 20 quackgrass accessions was carried out, the result showed E18 was the best, the following was E04、E08、E09, these materials had potential exploitation and breeding value. By comprehensive assessment, E18、E04、E08 could be used as the primary selection for turfgrass breeding.(6)The results of esterase and peroxidase isozyme from 32 materials of E.repens showed that 16 enzyme belts emerged in sum. Among these belts, the emergence frequency of 10 enzyme belts was high, as meaned that the accessions of E.repens had the similar origin. Based on the esterase and peroxidase isozyme bands, in according to Jaccard similarity coefficient, cluster analysis was done with UPGMA method, 32 materials were divided into 4 categories, the enzyme characteristics of materials collected from altai region, Xinjiang, showed certain correlation with environment condition.(7) Based on the results of RAPD amplification reaction of 32 materials of E.repens, 264 bands were obtained by 18 effective random primers, and the polymorphism rate was 93.7%, which suggested that high DNA polymorphism and abundant genetic variation among E.repens materials existed. By clustering analysis based on RAPD, at the point of genetic similarity coefficient 0.373, all materials could be divided into 5 categories, and the categories had a certain correlation with environment condition.(8)Through study on morphological characteristics, drought resistance, turf-using characteristic and genetic diversity of wild Elytrigia repens (L.) Nevski in Xinjiang, the result showed great variation existed for different characteristics among accessions, abundant genetic diversity also existed among accessions, As had the value to be exploited, high drought resistance accessions and excellent turf–using accessions obtained by selection made the base for new quackgrass line breeding更多还原