【作者】 李伟琼；

【导师】 王铁娟；

【作者基本信息】 内蒙古师范大学 ， 植物学， 2009， 硕士

【摘要】 差不嘎蒿(A.halodendron Turcz.ex Bess)、褐沙蒿(A.intramongolica H.C.Fu)和黑沙蒿(A.ordosica Krasch.)均是菊科蒿属的半灌木,是干旱区重要的固沙植物,也是荒漠植被中的主要建群种和优势种,在荒漠区的生态环境保护中发挥着极其重要的作用。三种沙蒿亲缘相近,形态特征十分相似,对三种沙蒿间亲缘关系的研究,可更加深入地了解龙蒿组种间的亲缘演化关系,为其种间的分类提供更多分子水平上的依据。本文利用ISSR技术结合解剖特征及与环境因子的关系,对三种沙蒿进行研究,结果如下:1.三种沙蒿均具有高的遗传多样性,不仅表现在物种水平而且表现在种群水平上。种群水平,多态位点百分率为褐沙蒿>黑沙蒿>差不嘎蒿,物种水平的顺序与种群水平一致,但三种沙蒿的值非常接近,褐沙蒿略高。从Nei基因多样度与香农多样性指数看,物种水平与种群水平均为差不嘎蒿>黑沙蒿>褐沙蒿,与多态位点百分率的顺序相反,说明差不嘎蒿的多态性低但均匀性高,褐沙蒿则相反。三种沙蒿的基因分化系数为差不嘎蒿Gst=0.1041、褐沙蒿Gst=0.0757、黑沙蒿Gst=0.0768,表明三个种均是绝大部分的遗传变异存在于种群内。2.三种沙蒿17个地理种群的聚类分析显示,以种为单位聚为三大支,同一物种的各种群均能聚到一起,反映出三个种具有一定的分化。从种间关系来看,黑沙蒿5个种群构成的一大支首先与褐沙蒿的7个种群构成的大支相聚,然后再与差不嘎蒿5个种群的大支聚到一起,表现出黑沙蒿与褐沙蒿关系更为密切,物种水平上的聚类显示了同样的结果。3.由解剖特征可知,三种沙蒿的叶及营养枝的解剖结构特征一致,反映了它们之间较近的亲缘关系。上下表皮的角质层均较厚,栅栏组织与海绵组织的比值较大,说明了三种沙蒿较强的抗旱能力。4.差不嘎蒿、黑沙蒿的营养枝及叶解剖结构与环境因子的相关性分析显示,随着年降水量的降低,差不嘎蒿的叶上表皮角质层呈变厚的趋势,即叶上表皮角质层随干旱而变厚,以减少水分的散失。从叶下表皮角质层来看,差不嘎蒿随寒冷指数降低而变厚,黑沙蒿则随极低温的下降而增厚,表现出两种植物的叶下表皮角质层均随低温而增厚,叶厚也有同样的趋势,黑沙蒿叶厚随年均温的降低而增厚。差不嘎蒿栅栏组织厚度随着生长季降水量的减小而增大,髓茎比随着湿润指数的增大而增大,均体现出对水份的适应性。黑沙蒿营养枝基部直径则与最暖月温度有关,呈现正相关关系。再有,对于两种植物均表现出随温和度减小,营养枝皮层厚度增大,即表现出寒冷使皮层增厚。从决定系数(R2)来看,只有差不嘎蒿叶上表皮角质层与年降水、黑沙蒿营养枝基部直径与最暖月平均温度的R2值高,表明在这两个方面反映出的规律性强。更多还原

【Abstract】 A. halodendron Turcz.ex Bess、A. intramongolica H.C.Fu and A. ordosica Krasch. are subshrub belonging to genus Artemisia of Compositae. They are edificators or dominant species of sand vegetation, important fixation plants and have played an important role in desert eco-environment protection. The three species have close kinships and quite similar morphological characteristics. The research of their kinships redounds to probe into the phylogeny of section dracunculus of genus Artemisia and provide more molecule-level proofs for the classification among the species. In this paper, the tree species were studied by ISSR makers being combined with anatomic characteristics and environmental factors, the results were as follows:1. The three species had high genetic polymorphism in both species level or in population level. In population level, the sequence of polymoiphic loci percentage was: A. intramongolica > A. ordosica > A. halodendron. The sequence of species level was the same, but the values were very close to, only A. intramongolica slightly higher. Nei’s gene diversity index (H) and Shannon index(I) in both species level or in population level, the sequence all were: A. halodendron > A. ordosica > A. intramongolica, opposite to polymoiphic loci percentage. It indicated that A. halodendron had lower polymorphism and higher evenness, A. intramongolica was contrary. The genetic differentiation among populations (Gst) of the tree species were: A. halodendron Gst=0.1041, A. intramongolica Gst=0.0757, A. ordosica Gst=0.0768, it indicated more variations existed within the populations.2. The cluster analysis on 17 geographical populations of the three species demonstrated that the populations of every species were clustered together respectively to three branches, it reflected the definite genetic differentiation among the species. To the relations of the species, the branch of five populations of A. ordosica were clustered together with the branch of seven populations of A. intramongolica firstly, and then with the populations of A. halodendron. It indicated that kinships were nearer between A. ordosica and A. intramongolica. The cluster analysis on the species level demonstrated the same results.3. According to the anatomic characteristics,the leaves and foliage branch of the three species were coincident, reflected that they had quite close kinships. The thick upper and lower cuticle and the big ratio of the palisade mesophyll to spongy mesophyll indicated that the three species had strong drought-resistance ability.4. Analyzing the correlation between the anatomic characteristics and environmental factors to the A. halodendron and A. ordosica , the result showed that: 1) With an decrease of annual precipitation, upper cuticle thickness of the A. halodendron increased, indicated the upper cuticle thicken with the drought to decrease the dissipation for water. 2) The lower cuticle thickness, both of the A. halodendron and A. ordosica tended to thicken with the temperature decrease. The leaf thickness of A. ordosica also had the same tendency. 3) The palisade mesophyll thickness of the A. halodendron tended to thicken with the growth season precipitation decrease and the ratio of medulla to stem increase with the wetness index increase, these reflected the adaptability to water. 4) It was the positive correlation between diameter of basal foliage branch of the A. ordosica and the mean temperature of the warmest month. 5) With the decrease of the temperateness, the cortex thickness of foliage branch of the two species thicken, indicated the coldness made cortex thicken. 6) According to the coefficients of determinant (R2), the value was high only in the upper cuticle thickness and the annual precipitation for the A. halodendron, the diameter of basal foliage branch and the mean temperature of the warmest month for the A. ordosica, it indicated the rule was obvious in the two aspect.更多还原