【作者】 张帆；

【导师】 汪旭东； 吴先军； 周开达；

【作者基本信息】 四川农业大学 ， 作物遗传育种， 2003， 硕士

【摘要】 特异单倍体129-B来源于多胚苗CYAR₀₂，152-A来源于多胚苗9003，154-B来源于多胚苗9004。来源于9003基础群体的同源三倍体SAR-3和同源四倍体SAR-4与二倍体杂交，后代表现出早代稳定性。而单倍体有无此特异性呢?本文对此进行了研究探讨。以129-B、152-A和154-B为研究材料，主要从以下两方面进行了研究：①减数分裂中染色体行为，特别是染色体分离方式，n配子的发生机制；②单倍体的生殖特性以及与二倍体的杂交习性。其初步结果如下： 1、单倍体与二倍体的光合作用比较研究，结果表明：在相同的光照条件下，单倍体净光合速率与二倍体植株相差不大，说明单倍体的代谢正常，似乎个体小并不影响单倍体的代谢能力。 2、用1％I₂-KI溶液使花粉染色放在低倍镜下观察，结果是特异单倍体的花粉育性为4.12％，高于普通单倍体花粉育性（1.23％），低于二倍体植株花粉育性（95％）。 3、单倍体花粉母细胞减数分裂观察表明：单倍体在减数分裂时，因缺少同源染色体而不能正常配对。在终变期，常以单价体的形式存在，但特异单倍体有极少数的多价体存在，在所观察的120个细胞中，其联会构型均值为11.12Ⅰ+0.25Ⅱ+0.09Ⅲ+0.07Ⅳ；在中期Ⅰ，纺缍体高度凌乱无序；后期Ⅰ染色体随机分离，形成多种多样的分离方式，如6-6、4-8、3-9、5-7、0-12、2-4-6分离方式等，但以6-6分离方式为主，比例为11.67％，0-12分离形成可育配子的比例为4.12％。而普通单倍体在终变期为12Ⅰ，后期染色体随机分离，形成可育配子的比例为0.9％。 4、单倍体植株胚囊结构观察表明：单倍体的正常胚囊其结构完整，类似于二倍体的胚囊。内部结构完整，分化完全，具卵器、2极核和反足细胞，并且呈典型的蓼型结构。但这种正常胚囊的形成数极少。据统计，在所观察的566个单倍体子房的石蜡切片中，仅83个子房形成胚囊，比例为14.6%。其中形成正常胚囊的有29个，占5.20％，高于雄配子育性（4.12％）。在观察中发现，成熟胚囊中有一部分异常胚囊，如：只有一个极核，或只有极核无卵细胞，或无反足细胞等。 5、单倍体自交不结实，与二倍体杂交结实率低，20％左右的花粉能在单倍体柱头上萌发并顺利伸入柱头到达珠孔。障碍主要在受精过程中出现，存在单受精（2.33％）与不受精（93％）现象。也存在原胚发育异常或缓慢，胚乳退化等现象。分析其主要原因在于：①雌配子不育；②雄配子不育；③雌雄配子之间的亲和性障碍；④雌雄配子发育不同步；⑤单受精。 6、特异单倍体与二倍体杂交结实率（l .3%）高于普通单倍体（0.014%），原因在于:‘①雌雄2N未减数可育配子的形成;②大小抱子性母细胞避开减数分裂直接进行有丝分裂，形成正常可育的配子。 7、对单倍体X二倍体后代特性进行分析研究，结果表明:①绝大多数为二倍体，少数植株为非整倍体。据统计，16株F，中，12株为二倍体，2株为嵌合体，2株为非整倍体;②微卫星标记分析，Fl中没有扩增出杂合带型;而父本和母本的标记带型，在F，中均同时出现，F，全是真实杂种。③在单倍体与二倍体杂交的FZ群体中，wl（152--AxR363F2）和WZ（154书X R363 FZ）表现出早代稳定特性。经统计分析表明株高、抽穗期、有效穗、穗长等几个重要农艺性状上与对照汕优63无显著差异;微卫星标记分析，具有稳定性的株系内个体之间的带型一致。更多还原

【Abstract】 129-BJ52-A and 154-B,which are haploids, are derived from twin-seeding basic populations of CYARo2. 9003 and 9004. SAR-3 and SAR-4, which are autotriploid and autotetraploid respectively, are derived from twin-seeding basic populations of 9003 and 9004. In earlier research, an important phenomenon was discovered, which was that some F2 populations of diploids Fl individuals from the cross of polyploid xdiploid were uniform. Whether haploid has the character or not is the target of this research. In this research, two aspects were explored for many lines from 129-8,152-A and 154-B: First, chromosome behavior during meiosis, especially chromosome segregation mode and the generating mechanism for n-gamete. Second, reproductive behavior of haploid and embryo development for cross of haploid xdiploid. The main results are as following:1, Study on photosynthesis of haploid and diploid showed that there was little difference in net photosynthetic rate between them, haploid metabolism is normal, and miniature apparatus seem not affect the metabolism. 2. The results of pollen stainability identified with the method of 1%I2-KI revealed that especial haploid pollen stainability was 4.12%, higher than normal haploid(1.23%), while lower than the normal diploid (95%).3. The haploid PMCs were observed and the results showed: (1)Because of the absence homologous pairing, haploid mostly formed univalents and only a little mutivalents at diakinesis, the average paring form wasl 1.12 I +0.25 II-KX09III+0.07IV. (2)During anaphase I in the haploid,varying numbers of chromosomes move to the two poles. Distributions of 6:6,4:8,3:9,5:7,0:12 and so on, which resulted in many sterile gametes. In short, haploid had irregular meiosis, so the sterility of haploid is relatively low.4. Observations to the embryo sac structure of haploid showed that: a few normal embryo sacs(5.20%)differentiate completely, which have egg apparatus, tow pole nucleus and antipodal cells, while the majority of them(94.8%) were abnormal, for example they have one-polar nuclei, multi-polar nuclei, no-egg apparatus and no- antipodal cells.5. Haploid inbreeding was sterility and seed-setting for the cross of haploid xdiploid was relatively low, but 20% diploid pollens can geminate on the pistile of haploid, penetrate into, and arrive at micropyle. The barriers of crosses may occurred during fertilization, including single-fertilization (2.33%), non-fertilization (93%), abnormal or prolonged development of proembryo and degeneration of endosperm. The reasons of it are as following: (1)female gamete was sterility,(2)male gamete was sterility. (3)The barriers of affinity between female gamete and male gamete. (4)The non-synchronic development of female gamete and male gamete.(5)single-fertilization.6. Seed-setting for the cross of especial haploid*diploid was higher than normal haploidxdiploid, The reasons of it are as following: (1)Unreduced 2N gametes of female and male formed.(2)The mother cells of macrospore and microspore directly go mitosis by-passed meiosis to form normally fertility gametes. (3) Apomixis.7. The identification for the character of progenies of haploidxdiploid revealed that:(1)Most of the progenies were diploids and only a few of them were aneuploids.(2)SSRs marker analysis showed that all the FI were true hybrids. Markers for either parent could be present in FI progenies.(3)Two F2 populations from FI strains were uniform: statistical analysis showed that compared with Shan You 63, there was no much difference in height, days to heading, productive tillers per plant, length of panicle. SSRs marker analysis showed that all bands were uniform among individuals of F2.更多还原