【作者】 李向拓；

【导师】 王辉； 张世煌；

【作者基本信息】 西北农林科技大学 ， 作物遗传育种， 2005， 博士

【摘要】 为了研究热带玉米群体POB21和POB32经过控制双亲混合选择后不同轮次间的遗传多样性变化,采用了两年四点的试验,2004-2005年间,分别在海南、陕西、河南和北京四点进行POB21和POB32不同轮次间的田间农艺性状变化的研究;利用解剖学显微镜进行了POB21和POB32的原始群体和末改良轮次即POB21C₀、C₇和POB32C₀、C₅的雌雄穗分化观察;利用SSR标记,进行分子水平方面遗传多样性的研究。旨在从形态学、解剖学和分子水平来研究POB21和POB32在适应温带过程中的遗传多样性变化,探讨有关性状的变化趋势,为进一步改良或利用新的外来种质提供一定的理论基础。通过研究得出如下结论: 1 从农艺性状上看,轮次间的响应基本上与其实际选择增益相吻合。散粉期、吐丝期、散粉-吐丝期间隔（ASI）、株高和穗位高等降低,结实长、穗行数、百粒重、出籽率和籽粒产量等有了明显改善。随着改良轮次的增加,轮次间的变异系数减小,即轮次间的遗传变异有些降低。一些相关性状的光敏感程度得到了一定的降低。系统聚类分析结果表明,14个轮次可以聚为不同的两类,一类是POB21不同的8个轮次,即POB21C₀、C₁、C₂、C₃、C₄、C₅、C₆、C₇;另一类为POB32不同的6个轮次,包括POB32C₀、C₁、C₂、C₃、C₄和C₅。 2 在解剖学上,热带玉米群体POB21和POB32在适应温带过程中穗分化变化研究。发现在雄穗的穗分化中,经过适应性改良的末改良轮次POB21C₇分化阶段Ⅰ和Ⅲ所需时间分别比原始群体C₀缩短了8天和5天;而群体POB32C₅的分化阶段Ⅰ和Ⅲ所需时间缩短了6天和4天。在雌穗分化中,POB21C₇穗分化阶段Ⅰ、Ⅲ和Ⅳ分别比C₀缩短了12、4、4天,而POB32C₅的穗分化阶段Ⅰ、Ⅲ和Ⅳ分别比C₀缩短了9、3和2天。随着改良轮次的增加,群体POB21和POB32的雌穗与雄穗分化阶段发生的时间间隔在缩短。无论是雌穗与雄穗的分化阶段经历时间,还是相同分化阶段开始发生时间的间隔,经过适应性改良的POB21C₇和POB32C₅都比原始群体C₀更接近于当地对照户4。 3 在分子水平上研究热带玉米群体POB21和POB32在适应温带过程中的遗传多样性变化,利用筛选出的77对引物,获得了271个等位基因;平均每个位点等位基因数为3.6个,变化范围为:2-8个。POB21和POB32群体间不同轮次的遗传距离较大,更多还原

【Abstract】 In order to study the change of genetics diversity among circles in POB21 and POB32, one experiment was carried at four locations in 2 years. The changing of agronomic traits among different circles was studied in the field at Hainan, Shaanxi, Henan and Beijing during 2004-2005, observing the spike differentiation of POB21C₀ and C₇, POB32C₀ and C₅ and studying the genetic diversity with SSR marks at molecular level. To get the change of genetics diversity during adapting temperate zone on the three level of morphology, anatomy and molecular, it will supply us some theory base about improving and utilizing new exotic germplasm. The results of this thesis indicated that,On the view of agronomic traits, the response among circles is similarity with genetic gain. The time got shorter about days to anthsis, days to silking, the internal of anthsis and silking, plant height and ear height became lower than that of original population C₀. Other traits had improved such as fertile length, rows per ear, 100-kernal weight, the rate of grain-production and yield. The coefficient of variation became small, which showed that genetic variation got lower among circles. Degree of photoperiod-sensitive of some traits decreased with the increasing improved circles. Two large cluster were divided among 14 different circles, one is population POB21 with 8 circles including C₀,C₁,C₂,C₃,C₄,C₅,C₆ and C₇, the other one is POB32 with 6 circles, including C₀,C₁,C₂,C₃,C₄ and C₅.At anatomy level, changing of spike differentiation in tropical maize population POB21and POB32 adapting temperate zone was studied. Comparing with the process of POB21 and POB32 tassel development in original population C₀, the internal of differentiation phase I and III in improvement circle was shorten 8 days and 5 days in POB21C₇, 6 days and 4 days in POB32C₅ respectively. Compare to the process of ear development in POB21C₀ and POB32 C₀, the internal of phase I, III and IV in POB21C₇ was reduced 12 days, 4 days and 4 days and respectively, while 9 days, 3 days and 2 days were reduced in POB32C₅. Along with improvement circle increasing, the gap of the beginning time between tassel and ear was reducing at different spike differentiation phase in POB21 and POB32. Regardless of the internal of spike differentiation, the gap of the beginning time between tassel and ear at different spike differentiation phase, the improvement circle was more similar than original population C₀ in POB21 and POB32.At molecular level, changing of genetic diversity in tropical maize population POB21 and POB32adapting temperate zone was studied. 271 alleles were got by 77 selected primers. There were 3.6 alleles at one locus. Its changing rang was 2-8. The genetic distance of different circles between POB21 and POB32 was longer than that between different circles in POB21 or POB32. Based on the, genetic distance among different circles in POB21 and POB32, 14 different circles were divided into two kinds, which one was POB21 and the other was POB32. There were many different changes on the population genetic structure between POB21Q, and POB21C7, between POB32Q, and POB32C5, such as the index of population genetic diversity, the expected heterozygosity, the number of allele and the allele frequency. The index of genetic diversity deceased between the original population and the improved circles, which indicated that the variation degree in the population deceased during the improvement process of adapting temperate. The gene flow was so smooth that it kept back the genetic variation caused by genetic drift in the population.In order to assess the genetic diversity between POB21C0 and POB21C7, POB32Q, and POB32C5, the sampling capacity from one population was first studied. This study focused on the changes in genetic diversity index, allele number, genotype and genetic distance among samples with different capacity. The objectives were to get the suitable sample capacity for studying population. When genetic diversity index or grouping heterosis group was studied in populations, 10 plants or so were chosen randomly in POB21 and POB32;When the allelic number, genotype, and genetic distance between plants in population, the sample capacity was over 30 in POB21 and POB32.In the conclusion, improvement of spike differentiation was anatomic base for the suitability improvement in tropical maize population adapting temperate zone, and the sampling capacity in different researching objective was different. On the view of response among circles, genetics gain and clustering, it was effective improving the suitability of tropical maize population adapting temperate with controlling bi-parental mass selection.更多还原