【作者】 路超；

【导师】 李云；

【作者基本信息】 北京林业大学 ， 林木遗传育种， 2010， 博士

【摘要】 同源四倍体刺槐(Autotetraploid Robinia pseudoacacia)是通过人工诱导二倍体刺槐体细胞染色体(2x)加倍而育成的木本植物同源四倍体(4x),具托叶刺少,叶片的粗蛋白、矿质营养物质等营养成分高等优点。为系统的了解同源四倍体刺槐花序变异的规律及其机理,于2007-2009对位于北京市延庆县的同源四倍体刺槐实验林的花序的生长发育全过程进行观察研究,主要研究内容及结论如下。通过表型观察,对同源四倍体刺槐花序结构的类型进行统计、分类,并对不同类型花序间的表型变异,花序生长情况变异,以及他们在不同个体和不同年份间的比例变异,以及花序上小花结构变异进行了研究。在同源四倍体刺槐中发现一种新的花序变异类型,物候期变异花序—晚花序,它的特点是物候期延后,但花序结构没有变异,而且发生率极不稳定；同源四倍体刺槐中的花序结构变异花序的生长规律十分相似,但与二倍体刺槐间存在一定差异；各类型花序的比例在不同个体和年份间差异很大；花序上小花的变异主要表现为发育的不同步性和不同级别小花间的结构变异。利用植物显微技术和植物形态学方法,对同源四倍体刺槐花序形态发育的过程进行了研究。研究表明,同源四倍体刺槐花序发育的全过程可分为9个阶段,并发现对同源四倍体刺槐花序变异起到决定性作用的时期为一级花序原基发育后期,在这一时期变异花序中的二级结构开始分化,而其来源为主花序轴上的原侧生分生组织和脱分化形成的新分生组织；同时发现同源四倍刺槐开花期比二倍体刺槐延长15d左右。利用DNA甲基化抑制剂5-azaC对同源四倍体刺槐中处于一级花序原基发育期的冬芽进行处理,以期探明DNA甲基化是否对同源四倍体刺槐花序变异产生影响；首次对刺槐中的花分生组织决定基因TFL1和LFY进行克隆和分析,为以后的分子遗传学研究打下基础。结果显示,5-azaC对同源四倍体刺槐的冬芽发芽率、花序生长和花序变异率都有一定的抑制作用,同时能够促进花序提前开花；从刺槐的基因组DNA中克隆出的花分生组织决定同源基因RpTFL1和RpLFY的部分片段,通过比对发现它们与豆科其他植物的同源基因的同源性都在90%左右,同时没有在同源四倍体刺槐与二倍体刺槐的基因序列上发现差异。更多还原

【Abstract】 Autotetraploid Robinia pseudoacacia (4x) is formed by doubling somatic chromosome of diploid (2x) in Korea, and it shows many advantages, such as fewer stipular thorns and higher contents of nutrient (such as crude protein and mineral) than those of diploid. To understand the laws and mechanism of inflorescence variations in autotetraploid Robinia pseudoacacia, from 2007 to 2009, the whole development of inflorescence was researched, which is in Yanqing country, Beijing. The research contents and main conclusions are as follows.By phenotypic observation, the variations in inflorescence architecture, growth pattern, and the proportion of inflorescence types among different individuals and years were studied. A new inflorescence type-later inflorescence was found, whose phenological phase was changed but structure was not, and it was instable.. The growth patterns of inflorescence types in autotetraploid were not found different, but different with that of diploid. The development asynchrony and structure mutation were in the floret, which is on the second inflorescence axis.Through the methods of botanical microtechnique and plant morphology, growth phases in the whole inflorescence development process were detected. As a result, the whole growth process was divided into nine phases. The crucial phase for variation was detected, which is later first axis primordium phase, and new meristem was found in this phase, which finally differentiation into mutated structure; and the flowering time in autotetraploid was 15d longer than that of diploid.To illuminate the mechanism of these variations in Autotetraploid Robinia pseudoacacia,5-acazC was used to treat the buds, which is in first axis primordium phase, and the floral meristem identity genes were cloned from Autotetraploid Robinia pseudoacacia first time. In the 5-acazC treating test, the germination rate of buds, inflorescence growing and variations were all obviously restrained, and the phenomenon of.early flowering was observed. Partly DNA sequence of LFY and TFL1 homologous genes were cloned, and no difference of sequence was found. The homology of two genes with other Leguminosae plant is 90%,.更多还原