【作者】 吴超；

【导师】 郑勇奇；

【作者基本信息】 中国林业科学研究院 ， 林木遗传育种， 2007， 硕士

【摘要】 本文以乡土树种花楸树（Sorbus pohuashanensis （Hance） Hedl．）为研究对象，采用等位酶技术及表型性状分析，通过分析交配系统和遗传结构，深入了解花楸树遗传多样性及变异规律；通过低温层积，了解花楸树种子的萌发特性；通过种子萌发抑制物的生物测定及低温层积过程中内源激素含量变化，探求导致种子休眠的原因；通过催芽试验，寻找促进花楸树种子发芽的最佳方法。本研究旨在为花楸树的种质资源收集、保存和利用以及育苗技术等提供科学理论依据。研究结果如下：1．以4个种源共80棵单株为材料，分析花楸树表型变异，方差分析结果表明，群体间和群体内的差异均达到极显著水平。各性状间的变异系数相差较大，变幅为5.2-14.51％，叶性状的变异较果实性状大；平均分化系数（Vst）为48.2％，表明群体内的变异是花楸树遗传变异的主要来源。2．以花楸树3个种源共60个家系为材料，应用水平淀粉凝胶电泳，分析了4个酶系统的遗传变异，共得到7个酶位点，其中4个为多态位点，多态位点百分率P=57.14％，每个位点的平均有效等位基因数ne=1.6790，群体期望杂合度He=0.2443，高于多年生木本被子植物的平均值（ne=1.20，He=0.143）；基因分化系数较低，为0.0574，表明花楸树各种源间相似性很高，花楸树群体内的遗传变异是花楸树变异的主要来源；多位点异交率（t_m）为0.826-1.000，表明花楸树有较高的异交率。表明花楸树的遗传基础广泛，适应环境的能力较强。3．种子休眠机理分析发现花楸树种子是胚休眠，不存在种皮限制因素；花楸树种子胚休眠的主要原因是胚内存在萌发抑制物质，其中之一是ABA；打破休眠的较好的方法是1500ppm GA₃预处理花楸树种子，再结合低温层积45d，可以促进种子整齐萌发；精细管理是培育壮苗的关键。4．花楸树在形态和分子水平上具有丰富的遗传变异，为优良品种的遗传改良提供了选育基础；变异主要来自于群体内，在良种选育过程中，群体内优良单株的选择是花楸树遗传改良的一个重要方面；基因保存策略应当考虑采用就地保存策略，可更好地保护花楸树的遗传多样性和优良遗传基因。更多还原

【Abstract】 Genetic diversity and variation patterns of Sorbus pohuashanensis were studied throughanalysis of mating system and genetic structure of different populations using allozymemarkers and morphological traits, aimed to lay a theoretical basis for germplasm collection,conservation and utilization of the species. Bioassay of inhibitors in different parts of the fruitwas carried out and endogenous hormones were measured to understand the factors leading toseed dormancy. Treatments with differet concentration of endogenous hormones combinedwith low temperature stratification were used to promote germination. The results are asfollows:1. Morphological diversity was studied among 80 individuals of S. pohuashanensis. Variationanalysis of all characteristics were significantly different among populations and amongindividuals within population. CV was varied from 5.2% to 14.51%, markably differentamong phenotypic characteristics. The variations in leaf traits were greater than those offruit traits. Average of the phenotypic differentiation coefficient （Vst） was 0.4820,indicating that the genetic variation within population was the main sources of geneticdiversity in S. pohuashanensis.2. Genetic Variation of 4 allozymes was studied by using horizontal starch-gel electrophoresisamong 60 families of S. pohuashanensis. A total of 7 loci were assayed, and 4 loci werepolymorphic. The percentage of polymorphic loci （P） was 57.14%. The average number ofeffective alleles （ne） per locus was 1.6790. The expected heterozygosity （He） was 0.2443,which was higher than the average of woody perennials angiosperms （ne=1.20, He=0.143）.Gene differentiation coefficient of S. pohuashanensis was so low as 0.0574; showing thatthere was high similarity among different populations. The estimated Multi-locusoutcrossing rates were from 0.826 to 1.000. All the above parameters showed that S.pohuashanensis was great in its genetic diversity with strong adaptive potentials toenvironment.3. The analysis of seed dormancy mechanism of S. pohuashanensis showed that seeddormancy was due to embryo, not the seed coat. The existence of inhibitors in the embryo,including ABA induced embryo dormancy. Seed pretreatment with 1500ppm GA₃ for 1.5day combined with cold stratification for 45 days, could be used to break seed dormancy.It could meet the need of seedlings production. Fine management was one of the keymeasures to raise robust seedlings.4. The rich genetic diversity at morphology and molecular level of S. pohuashanensis provided a basis for selection and breeding for the genetic improvement of the species.Selection of superior individuals within population was an important step of geneticimprovement of S. pohuashanensis due to its greater variation within populations. In situconservation should be considered in order to better maintain genetic diversity of S.pohuashanensis.更多还原