【作者】 鄢金灼；

【导师】 冯虎元；

【作者基本信息】 兰州大学 ， 植物学， 2008， 硕士

【摘要】 丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)是一类与植物互惠共生的微生物。在湿地生态系统中,AMF具有提高宿主对营养物质吸收,改变宿主生长发育水平,增强宿主抗盐分胁迫、抗污染能力等生态学功能。因而,对AMF的生态学研究已经成为一个热点。目前,已有很多这方面的研究成果出现,但是,对湿地环境中,AMF和宿主主要受到哪些因素的影响,以及这些因素的影响力,并没令人信服的结论。本实验研究位于柴达木盆地边缘的大苏干湖湿地植物芦苇(Phragmites australis)AMF不同季节(7月份、10月份)、不同生态型(水生、盐生、沙生)间侵染率、孢子种群密度、多样性的差异,探讨AMF与宿主、土壤理化性质之间的关系,揭示湿地植物根际AMF生态学特征,主要结论如下:1、单子叶植物芦苇根部AMF菌丝侵染率水平较低,仅为5.76%;不同月份之间的大小关系是:7月份(6.67%)＞10月份(2.73%),即在芦苇生长发育旺盛的季节,AMF侵染率水平较高;不同生态型之间的大小关系是:水生型(10.28%)＞沙生型(3.84%)＞盐生型(3.21%),表明水分不是影响AMF侵染率水平的主要因素。菌丝侵染率水平和芦苇湿重(R~2=0.480,P＜0.01)、芦苇平均株高(R~2=0.614,P＜0.01)均显著正相关;多元线形回归分析(R~2=0.204,P＜0.01)的结果表明,AMF菌丝和泡囊侵染率水平主要受宿主影响,其他因素对之影响不显著。2、7月份和10月份,孢子平均种群密度分别是1159和1611(单位:个/100g,下同),最高的是盐生型(2473),沙生型次之(518),水生型最低(390):盐碱化土壤中,AMF具有很高的孢子种群密度,甚至在1.0m深的土壤中也有较高的孢子种群密度。用PCA分析提取样地植物和土壤理化性质的主因子中,代表宿主物种多样性的因子和代表含盐量、有机碳含量的因子均与AMF孢子种群密度显著相关:用多元线性回归分析,得到AMF孢子种群密度的回归方程:Sd=-1943.618+1723.587Pbi+4.146Tpd(R~2=0.490,P＜0.001),式中,Sd:孢子总种群密度,Pbi:样地植物物种多样性,Tpd:植物总种群密度。样地植物物种多样性、植物总种群密度的偏相关系数分别是0.574,0.757,即植物总种群密度是影响孢子种群密度的最主要因素;样地植物物种多样性也是影响AMF孢子种群密度的主要因素,这可能与不同植物分泌的信号分子有关。3、通过外形性状对AMF孢子归类,总共得到28种孢子。用辛普森指数代表物种多样性发现,7月份的物种多样性(1.7673)小于10月(1.9882)。孢子物种多样性最高的是盐生型样地(1.9343),其次是水生型(1.8760),沙生型最低(1.6521)。AMF孢子物种多样性与芦苇种群密度(R~2=0.598,P＜0.01)、植物总种群密度(R~2=0.393,P＜0.05)、土壤含盐量(R~2=0.385,P＜0.05)显著正相关。通过多元线性回归分析得到孢子物种多样性的回归方程:Ssi=1.067+0.291Hf~2+0.290Si(R~2=0.567,P＜0.001),其中,Ssi:孢子物种多样性;Hf:宿主因素(PCA分析构建的影响宿主生物量的因子);Si:土壤含盐量。以上各个自变量的偏相关系数分别是0.728,0.510,表明宿主是影响孢子物种多样性的主要因素,其次是土壤含盐量。AMF孢子物种多样性随着土壤含盐量的增加而增加,这可能是由于AMF和宿主长期生长在盐碱化小生境中对环境适应的结果。4、从影响AMF主因子的得分因子散点图可以发现,不同季节同一生态型的点比较集中,而相同季节不同生态型之间的点相差较远,表明季节对AMF的影响不如生态型对AMF的影响显著。更多还原

【Abstract】 Arbuscular mycorrhizal fungi(AMF)is a kind symbiotic fungi of plants,plays an important role in wetland ecosystem in the aspects of nutrition absorption,growth, anti-salt stress and anti-pollutant,thus,it becomes hotspot of research.Util now,there is no convictional result of the factors influence wetland AMF in complex circumstance has gained.We experiment on spatial distribution(hydrophyte, halophyte,psammophyte),seasonal dynamic(July and October)of reed(Phragmites australis)AMF in Sugan Lake wetland,which lies on the edge of Chaidamu basin, and probe into relationship between AMF and its host,the main results showed:1.Reed,a kind of monocotyledon,has a low AMF hyphal and vesicular colonization rate.In July,AMF colonization rate(6.67%)is higher than that in October (2.73%).The colonization rate between ecotype was:hydrophyte(10.28%)＞psammophyte(3.84%)＞halophyte(3.21%),indicates AMF colonization was not affected by soil moisture.AMF hyphal colonization rate was positive correlate with reed wet weight(R~2=0.480,P＜0.01),reed mean height(R~2=0.614,P＜0.01). Multiple linear regression analysis results shows,AMF is mainly affected by its host.2.In July,mean AMF spore density is 1159 per 100g soil.Among ecotypes,the highest is halophyte(1688),psammophyte followed(635),halophyte is the lowest (532).There has a great amount of spore density in alkaline-saline soil,even in the depth of 1.0m.It suggests AMF may form a special structure with its host’s aerenchymatous to get enough oxygen to survive.Via PCA analysis,the component deputy of soluble ion(R~2=0.727,P＜0.05)and species richness (R~2=-0.422,P＜0.05)was positive correlate with AMF spore density.Using multiple linear regression analysis,we get the equation: Sd=-1943.618+1723.587Pbi+4.146Tpd(R~2=0.490,P＜0.001,Sd:spore density; Pbi:plant species richness;Tpd:total plant density).The partial correlation coefficient of Pbi and Tpd is 0.574 and 0.757;it means plant density was the most important factor to AMF spore density.Plant species richness affects AMF spore density too.May be secretion of different plants could increase sporulation of AMF,thus increase AMF spore density.3.We got 28 kinds of spores by phenotype.We use Simpson index as species richness,and find out the value in October(1.9882)is higher than July(1.7673). Values among 3 ecotypes is:hydrophyte(2.1562)＞halophyte (1.7829)＞psammophyte(1.6247).AMF spore richness is correlation with reed density(R~2=0.598,P＜0.01),total plant density(R~2=0.393,P＜0.05),soluble ion (R~2=0.383,P＜0.001).Using multiple linear regression analysis,we get the equation:Ssi=1.067+0.291Hf~2+0.290Si(R~2=0.567,P＜0.001,Ssi:spore spices richness;Hf:host factor,which was constructed by PCA analysis;Si:soluble ion). Partial correlation coefficient of Hf and Si is 0.728 and 0.510,indicates host is main factor affect AMF species richness,and then soluble ion.With the increasing of soluble ion,AMF species richness increasing too,it was the result of AMF long live in the alkaline-saline soil.4.Graph of AMF primary component shows,plots of same ecotype stand nearby, whereas plots of same season stand far from each other,indicates ecotype factor affect more to AMF than seasonal factor.更多还原