【作者】 桑子阳；

【导师】 马履一；

【作者基本信息】 北京林业大学 ， 森林培育， 2011， 博士

【摘要】 红花玉兰(Magnolia wufengensis)为马履一教授等发现的木兰科木兰属玉兰亚属新种,分布范围狭窄、数量稀少,生境破碎,自然更新困难,处于极度濒危状态,具有极高的科研价值和观赏价值,它作为城市绿化树种和山地造林树种具有广阔的推广应用前景。本文主要对红花玉兰花部性状、花芽分化和发育过程以及抗旱性进行了研究,以期为红花玉兰种质资源保护、遗传育种、引种栽培和推广利用提供参考依据。本文采用相关分析、主成分分析和聚类分析方法,对红花玉兰花部12个性状进行了连续观察和分析,并筛选出各具特色的优异性状单株；利用常规石蜡切片法,对红花玉兰有性生殖过程中大、小孢子发生和雌、雄配子体发育进行了细胞学观察；以1年生红花玉兰幼苗为试验材料,设置对照(CK)、轻度干旱胁迫(T1)、中度干旱胁迫(T2)和重度干旱胁迫(T3)4个水分处理水平,对红花玉兰抗旱性进行了研究。主要研究结果如下：(1)对红花玉兰花部12个性状的分析结果表明：花部性状遗传变异丰富,各居群内均以12瓣的花朵出现频率最高。聚类分析结果显示个体间的差异较大,同一居群内的个体聚类后分为不同的类别,居群内遗传变异丰富；居群间聚类分析结果显示高峰和栗子坪两个居群在花部性状多样性水平上聚为一类,表明两居群间的遗传多样性较低；影响红花玉兰花部性状的主成分有5个,其中花瓣数的贡献率最大,.达到42.91%；花部12个性状的相关分析结果表明各个性状间的相互影响较大,花柱长与雌蕊数、雄蕊长相互关系密切,花柱长的花朵表现出雌蕊数较多、雄蕊较长。(2)从优良单株类型来看,箩筐岩居群资源数量虽然较少,但花被片数目的变异类型丰富；黄粮坪居群花色、花型、大小及花被片形状变异丰富,但花被片数目比较稳定；栗子坪居群花的数目、颜色、形状变异都比较丰富,尤其以花被片数目的变异比较明显；高峰居群花的大小和颜色变异均比较丰富。对四个居群50个优良单株花部性状的聚类分析结果表明红花玉兰在居群内遗传变异丰富；主成分分析结果显示前三个主成分分别为花型因子、花大小因子和花色因子,聚类分析和主成分分析均与花部性状多样性研究结果一致。红花玉兰在长期的生长和演化过程中,对不同环境形成了不同的适应机制,从而产生了从个体到种群水平的不同变异现象。(3)对红花玉兰大小孢子发生和雌雄配子体发育过程的细胞学观察结果显示：该物种大小孢子发生和雌雄配子体的形成过程基本正常,不是导致其濒危的原因,红花玉兰的濒危原因有待于做进一步研究。(4)干旱胁迫抑制了红花玉兰幼苗的光合作用,随着干旱胁迫程度的加剧,株高、地径、生物量、净光合速率、气孔导度和叶片蒸腾速率逐渐降低,叶绿素a、叶绿素b和总叶绿素含量在T1处理略有升高,在T2和T3处理明显降低；胞间二氧化碳浓度、气孔限制值与水分利用效率保持相对的稳定,在轻度胁迫时略有上升,在中度、重度胁迫时转为下降的趋势,生物量分配更多地流向地下器官,地上器官生物量分配明显变少,造成根冠比增大。在不同的水分供应条件下,红花玉兰幼苗的渗透调节物质、膜脂过氧化及保护酶等参数均表现出明显的差异,随着干旱胁迫程度的加剧,红花玉兰幼苗叶片组织相对含水量有所下降,可溶性蛋白、脯氨酸、丙二醛含量逐渐累积升高,在同一处理水平,随着胁迫时间的延长,相对含水量呈下降的趋势,而脯氨酸表现出明显的累积现象；保护酶SOD、POD、CAT、APX变化规律基本一致均呈现先增加而后降低的变化趋势。干旱胁迫条件下,红花玉兰幼苗的生长受到一定程度的抑制,但能通过多方面的形态和生理调节来适应水分环境的变化,维持植物正常的生理代谢功能,保证了干旱胁迫下的正常生长,这些适应机制使其能够适应较大程度的干旱环境,表现出一定的抗旱耐旱能力,而成为水资源短缺城市造林绿化不可多得的新种质。更多还原

【Abstract】 Magnolia wufengensis is a new Magnoliaceae species found and nominated by Luyi Ma, Because the narrowness of its dispersal area, the scarcity of its individuals, M.wufengensis now is extremely endangered. This species has high ornamental value and scientific value, it has a broad application prospect as greening tree in urban and mountain area. In order to provide theoretical basis for its germplasm conservation, the breeding, introduction and cultivation, the promotion of its use, the researches on its floral traits, flower bud differentiation, development process, and drought resistance, were carried on in this paper,.Firstly, we make continuous observation and analysis of 12 floral traits of M. wufengensis, and selected individuals of different characteristics with the methods of correlation analysis, principal component analysis and cluster analysis; secondly, we make cytological observations of large and small microsporogenesis, female and male gametophyte in its sexual reproduction process through conventional paraffin section method. To study its drought resistance,1-year-old Magnolia wufengensis seedlings were potted under four different soil water content levels: optimal water content (CK), mild drought stress(T1), moderate drought stress(T2) and severe drought stress(T3).The main results are as follows:(1)the analysis of 12 floral traits indicated that Floral traits has a rich genetic variation; and flower with 12 petal has highest frequency in its populations. Cluster analysis shows that there is large difference between individuals, so that individuals within the same population clustered into different categories, there is a rich genetic variation within populations; cluster analysis among the populations shows that the diversity of floral traits growed up in Liziping and Gaofeng is in the same level with low genetic diversity among populations. Floral traits of M. wufengensis have 5 main components, the number of petals has the greatest contribution, reaching 42.91%. Correlation analysis of 12 floral traits shows that there is large interaction between different characters, the diversity of floral morphology and quantitative traits may be related to the long-term co-evolution of pollinating insects.(2)Considering the types of fine individual, there is fewer resource of M. wufengensis in Luokuangyan, the number of petals have various mutation types; The flower of M. wufengensis growed in Huangliangping have rich color, type, size and shape, the number of petals is stable; M. wufengensis growed in Liziping is rich of the number, color and shape of flower, in particular, the variation in the number of tepals is obvious; M. wufengensis growed in Gaofeng have rich variation on their color and size of flower. Cluster analysis on floral traits of 50 fine individuals in four populations indicates that M. wufengensis has rich variation within populations; principal component analysis revealed that the first three main components were the shape of flower, the size of perianth,and the color of petals, the result of cluster analysis and principal component analysis is the same as the result of research on diversity of floral traits.In the long-term process of growth and evolution, M. wufengensis has developed different adaptation mechanisms to adapt different environments, result in different variation from individual to populations.(3)The cytological observation of the process of large and small spores occurred and male and female gametophyte development of M. wufengensis shows that:This process is normal and not the reason of the endangerment of M. wufengensis, the real reasons for its endangement need further study.(4) Drought stress has a inhibitive influence on its photosynthesis, with drought stress became more and more serious, the heights, base diameters, biomass, Pn, Gs and Tr of the seedlings decreased significantly; Chla,chlb and chl content increased in treatment of T1, decreased in treatment of T2 and T3; Ci, Ls and the WUE kept stable, they are increasing slightly under low drought stress and then decreasing under high drought stress, but the root and the rhizome grew more than the above ground part, leading to higher root/shoot ratio. Parameters of osmolyte, lipid peroxidation and enzymes of seedlings showed great differences with different water supply leavel,. when drought stress became more and more serious, the RWC of seedlings’ leaves decreased, the contents of soluble protein, MDA and Proline accumulated and increased. In the same level, as the time of drought stress became longer and longer, the RWC in seedlings’leaves decreased, Proline increased obviously, the variation trend in SOD, POD, CAT and APX activity was increase at first and then decreased. We can concluded that the growth of M. wufengensis seedlings were negatively influenced by different degree of drought stress, but they could adapt to diverse water stress through plastic responses in morphology and photosynthesis, which proves that M. wufengensis has the tolerant ability of drought conditions. so it is a new urban tree for forestation in water shortage city.更多还原