花生栽培种(Arachis hypogaea L.)与野生种Arachis macedoi杂种F_1细胞遗传分析

开展花生种间杂交与杂种遗传研究对于探明种间亲缘关系、创制新种质和培育新品种具有重要意义。本研究利用花生栽培品种白沙1016(2n=4X=40,AABB)与二倍体野生种A.macedoi(2n=2X=20)进行种间杂交,通过胚拯救获得种间杂种F_1植株,进而对F_1进行了分子标记鉴定、有丝分裂与减数分裂观察和基因组荧光原位杂交(GISH)分析。结果显示,杂种F_1有30条染色体,其中既有来自母本白沙1016的染色质,又有来自父本A.macedoi的染色质;A.macedoi染色体经DAPI染色显示出明亮着丝粒带且包含一对"小染色体";白沙1016的A染色体组也显示出A.macedoi基因组标记探针的杂交信号;F_1减数分裂终变期染色体平均构型为0.6 III+8.27 II+11.6 I,减数分裂I期后、末期表现为不均等分裂。以上结果表明本研究获得了新的种间杂种F_1材料,所涉及的A.macedoi可能为A染色体组物种;A.macedoi染色体与花生A染色体组发生交换产生补偿性易位的几率比较大;减数分裂后、末期染色体的不均等分裂和非四分体形成,是杂种F_1表现高度不育的重要原因之一。     

水稻育种中的稻属种间远缘杂交

野生稻种中有一些优良性状，是目前栽培稻品种所不具备的。为了充分利用自然界的有利基因，进一步提高水稻新育成品种的产量潜力、品质与抗性，进行稻属种间远缘杂交研究是很有必要的。本文论述了野生稻种中目前已知的可利用性状，栽培稻与ＡＡ染色体组和非ＡＡ染色体组的种间杂交技术原理、方法及研究进展，提出了进行稻属种间远缘杂交应注意的几个问题，即目标的明确性、选材的精确性和技术路线的可行性。     

棉属种间杂交的胚胎学研究进展

棉属包括4个栽培种和35个野生种,这些种之间的杂交,很久以来都受到育种家们的重视。许多人想通过种间杂交来综合某些优良性状,但因常常遇到种间不亲和性特别是杂交后胚和胚乳常常败育等问题而告失败。于是,人们开展了细胞胚胎学的研究。另一方面,棉属具有花器大、易控制授粉以及一铃多籽、易获胚珠的特点,它又成为植物学家们进行胚胎学研究的好材料。特别是50年代以后,人们对棉属种间杂交做了大量的胚胎学研究,并取得一些进展。下面就这一问题作一简要综述。     

小麦族染色体组命名

目前,由于属间杂种可能不断增加,小麦与其近缘种属的染色体组命名可能发生混乱,G.Kim—ber和E.R.Sears在第六届国际小麦遗传讨论会上建议,这次会议应提出一些原则,以便统一染色体符号,避免重复。     

花生种间杂交后代的细胞学观察及其可育性研究

花生原产于南美洲,国外从三十年代就开始研究花生野生资源的利用,到五十年代初才获得了与栽培种杂交的不育三倍体杂种,到七十年代不少国家重视了这项研究,并获得了一些抗病性强、品质优良的种间杂种材料。 国内从近几年开始研究,我们先后对花生种间杂交亲和性及花生种间三倍体杂种染色体加倍技术等进行了报导,同时也获得一些杂种材料和连续与栽培种回交的子代材料,现正在选育中。 花生种间杂交,由于双亲的染色体倍性不同,杂交后产生的三倍体(2n=30)杂种尽管经过人工加倍处理后,F_1代杂种成为可育的异源六倍体(2n=60),     

棉花叶片气孔性状与染色体倍数相关性的观察

通过种间杂交转移异种棉的优良特性,培育新品种,是目前棉花育种技术研究的一个重要课题。对于鉴定种间杂种以及秋水仙碱处理不育杂种枝条的染色体加倍效果,细胞学观察是准确可靠的方法,但其要求较高,花时间多,在有些情况下难以进行。本试验以棉花种间杂交染色体倍数不同的后代为材料,观察其真叶下表皮气孔性状,对这些性状与棉株体细胞染色体倍数进行统计分析,以寻找能确定染色体倍数的间接指标。     

稻属叶绿体DNA限制性片段长度多态性

 对稻属（Oryza）的14个种和李氏禾属（Leersia）的 2个种共 138份材料进行了叶绿体 DNA限制性片段长度多态性的分析。用内切酶EcoRⅠ酶切、4 个叶绿体 DNA探针杂交,共发现10种叶绿体 DNA变异类型。在稻属各个种内没有观察到叶绿体 DNA的变异,叶绿体 DNA变异类型基本上以稻属的染色体组型水平划分,因此认为稻属的叶绿体 DNA在进化过程中变异程度很低。推测 CCDD组的O. alta、O. grandiglumis和O. latifolia 及 CC组的 O.officinalis 和 O. eichingeri各有共同的原始祖先。遗传距离分析显示 CC、CCDD、BBCC组之间亲缘关系很近,这3个组与 EE组亲缘关系也较近。李氏禾属的 2个种 L. perrieri 和 L. tisseranti 与稻属的遗传距离很远。     

同源四倍体高粱与约翰逊草种间杂交的研究

采用人工去雄及塑料袋简便杀雄法获得了６个同源四倍体高粱品系与约翰逊草的种间杂种。在４０条染色体水平上两种间杂交不存在遗传障碍，杂种Ｆ１在生长势上表现了巨大优势，在主要形式上介于双亲之间。     

小麦属与偃麦草属间杂交与物种的形成和命名

以小麦属(Triticum)与偃麦草属(Elytrigia或Thinopyrum)的杂交为例,论述了人工合成新物种过程中克服生殖隔离的几条途径;利用细胞学资料探讨了物种之间的亲缘关系以及染色体配对的控制等问题;从分类学角度对人工新种的命名问题进行了讨论。     

甜菜属(Beta Genus)种间杂交的研究

本文总结了我们在甜菜属一些物种的种间杂交工作,涉及物种有栽培甜菜、沿海甜菜、叶用甜菜、白花甜菜、小碗状花甜菜、平匐甜菜等。杂交取得了成功,获得了各种有价值的材料,如带有白菜甜菜染色体的栽培甜菜单体附加系系列,具有栽培甜菜和白花甜菜不同染色体组的各种异源多倍体（ＶＶＣ,ＶＶＶＣ及ＶＶＣＣ）的无融合生殖材料,具有栽培甜菜、白花甜菜和平匐甜菜染色体组的三种间杂种（ＶＣＰ）,这些都为世界首创。通过对杂种后     

利用C_0t-1 DNA对高秆野生稻和宽叶野生稻基因组的比较分析

为了揭示同为CCDD基因组类型的高秆野生稻和宽叶野生稻的起源和进化关系,用高秆野生稻C0t-1DNA作为探针,对其自身体细胞染色体与宽叶野生稻体细胞染色体进行荧光原位杂交并对其核型进行同源性聚类和比较分析。杂交结果显示宽叶野生稻和高秆野生稻同源性非常高,说明它们的亲缘关系十分接近,但区别也非常明显,两者的杂交信号存在显著不同。C0t-1DNA具有很强的种特异性和依赖基因组型的特异性,利用它进行荧光原位杂交能够更有效地研究物种基因组间的关系,为物种的划分和鉴定提供依据。另外,通过对高秆野生稻和宽叶野生稻两个异源四倍体基因组的中高度重复序列的比较分析,探讨了稻属异源四倍体可能的起源与进化机制。     

Molecular Cytogenetic Analysis of Spontaneous Interspecific Hybrid Between Oryza sativa and Oryza minuta

Genomic in situ hybridization (GISH) is a powerful tool to characterize parental chromosomes in interspecific hybrids, including the behaviour of autosynapsis and chromosome paidng. It was used to distinguish the chromosomes of Oryza sativa from wild species in a spontaneous interspecific hybdd and to investigate the chromosome pairing at metaphase I in meiosis of the hybdd in this study. The hybrid was a triploid with 36 chromosomes according to the chromosome nurnber investigated in mitosis of root tips. During metaphase I of meiosis in the hybrid, less chromosome pairing was observed and most of the chromosomes existed as univalent. Based on GISH and FISH (Fluorescent in situ hybridization) analyses, the chromosomes of the hybrid were composed of genomes A, B and C. Thus, it was believed that the hybrid was the result of natural hybridization between cultivated rice and wild species O. minuta which was planted in experimental fields.     

稻属种间天然异交种的分子细胞学鉴定

利用基因组荧光原位杂交（GISH）技术快速鉴定了栽培稻与野生稻的天然异交种的基因组组成,分析了该杂种在减数分裂中期Ⅰ的染色体配对情况。根据根尖细胞的染色体数目,发现该杂种是具有36条染色体的三倍体;通过减数分裂中期Ⅰ染色体的配对研究,发现该杂种染色体很少发生配对,绝大部分染色体以单价体形式存在;结合GISH技术的分析,证实该杂种是由A、B和C 3个染色体组组成。因此该杂种是栽培稻和小粒野生稻的天然杂交种。     

Comparative Analysis on Genomes from Oryza alta and Oryza latifolia by C0t-1 DNA

In order to reveal the origin and evolutionary relationship between two CCDD genome species, Oryza alta and Oryza latifolia, fluorescence in situ hybridization (FISH) was adopted to analyze the genomes of the two species with C₀t-1 DNA from O. alta as a probe. Karyotype was also comparatively analyzed between O. alta and O. latifolia based on their similar band patterns of the hybridization signals. There were a high homology and close relationship between O. alta and O. latifolia, however, the distinction between the hybridization signals was also clear. C₀t-1 DNA was proved to be species- and genome type-specific. It is suggested that C₀t-1 DNA-FISH could be more efficient to analyze the genomic relationship between different species. According to the comparative analysis of highly and moderately repetitive DNA sequences between the two allotetraploidy species, O. alta and O. latifolia, the possible origin and evolutionary mechanism of allotetraploidy of Oryza were discussed.     

Brassica cytogenetics-a historical journey and my personal reminiscence

This review gives a historical account of Brassica cytogenetics from chromosome number determination to the recent advancements in molecular cytology. Brassica cytogenetics started with the determination of somatic chromosome number of Brassica rapa (syn. B. campestris) by Japanese researcher N. Takamine. Russian botanist G.D. Karpechenko’s synthesis of Raphanobrassica was an important milestone representing the first example of a new species obtained through experimental hybridization. Japanese scientists Morinaga, and Nagaharu U pioneered genome analysis and unraveled the cytogenetic architecture of crop brassicas. The 1930s witnessed karyotype investigations on somatic chromosomes. Later, pachtene chromosome analysis led G. Röbbelen (1960) to propose the genetic constitution of the basic archetype. Brassica chromosomes are very small and lacking distinctive physical landmarks which makes difficult to generate reliable karyotypes. In recent years, classical cytogenetics has given way to molecular cytogenetics. Molecular karyotypes have been constructed using fluorescence in situ hybridization (FISH) with ribosomal DNA probes with individual chromosomes reliably identified. Since early 1950s, syntheses of natural alloploid species and of late, wide hybridizations between wild and crops species have successfully been carried out taking advantage of recent developments in tissue culture techniques. In early 1980s, the amenability of Brassica species for protoplast regeneration and fusion was demonstrated which enabled the syntheses of a large number of somatic hybrids including a substantial number of intertribal combinations. These experiments extensively helped in expanding the genetic base of existing allopolyploid species and increasing use of related wild germplasm for incorporating new genes which had not been accessible till recently. Comparative genomics between Arabidopsis and Brassica species have elucidated evolutionary processes. At present, Brassica and Arabidopsis regarded as model organisms in the field of experimental biology.     

Interspecific crossability and cytogenetic analysis of sexual progenies of Mexican wild diploid 1EBN speciesSolanum pinnatisectum andS. cardiophyllum

Mexican wild diploid species,Solanum pinnatisectum (S. pnt) (2n=2x=24, 1EBN: endosperm balance number) is a useful germplasm source of late blight and Colorado potato beetle (CPB) resistance in potato improvement. However, it is very difficult to cross this species with other 1EBNSolanum species. Sexual hybrids among three accessions ofS. pnt and two accessions ofS. cardiophyllum (S. cph) (2n=2x=24, 1EBN) were studied. There were large differences in the cross-compatibility among the genotypes and accessions from these two 2x-1EBN species. Interspecific incompatibility existed in the crosses betweenS. pnt andS. cph, in whichS. cph functioned only as the male parent. The crosses with accessions PI 275236 ofS. pnt produced 35 hybrids following the conventional propagation procedures. Seven hybrids were obtained with theS. pnt accession PI 275233 with the aid of embryo rescue, while hybridization involving accession PI 253214 resulted in no fruit. The cytogenetic analysis indicated that all of the hybrids derived from crosses of accession PI 275233 ofS. pnt withS. cph had 2n = 24 chromosomes and were pollen fertile. Crosses involving accession PI 275236 ofS. pnt produced both 2x (2n=24) and 3x (2n=36) hybrids. Meiotic analysis at metaphase I of pollen mother cells (PMCs) showed a fairly high rate of chromosome pairing that averaged between 10.10 and 11.10 bivalents per cell in most of the 2x hybrids, indicatingS. pnt andS. cph have the similar genome. A high frequency of trivalents and quadrivalents were observed in 3x hybrids derived fromS. pnt 2 ×S. cph 1, indicating homology exists among these chromosomes. These results suggest that specific gene(s) and not either differences between genomes or EBN controlled interspecific crossability and embryo development. The disease and insect tests on the 2x and 3x hybrids revealed that all have high levels of resistance to both late blight and CPB. Thus it could appear that selection of genotypes is a key for successful interspecific hybridization when using Mexican wild diploid species as a source of economic important traits.     

Visualizing Meiotic Chromosome Pairing and Segregation in Interspecific Hybrids of Rice by Genomic in situ Hybridization

Meiotic disturbances in F1 hybrids and their progenies are still major problems in wide hybridization.To investigate the genome affinity reflected in chromosome pairing and segregation,we studied chromosome behaviors during meiosis in two interspecific F1 hybrids[O.minuta×O.australiensis(Om×Oa,BCE genome)and Oa×O.ridleyi(Or,EHJ genome)]by using both traditional staining methods and genomic in situ hybridization(GISH).GISH analysis has been successfully performed on mitotic chromosomes to distinguish different Oryza genomes,but relatively fewer systematic analyses of meiotic chromosomes of interspecific hybrids have been reported.In the hybrids,highly irregular chromosome behaviors through meiosis resulted in producing microspores with unbalanced genome.At diakinesis of these two hybrids,most chromosomes present as univalent,with low frequency as bivalents and occasionally as trivalents.In a pollen mother cell,2 to 8 bivalents and 0 to 4 trivalents were observed in the hybrid Oa×Or,and 1 to 8 bivalents and 0 to 5 trivalents were observed in the hybrid Om×Oa.GISH results indicated that 51.52%bivalents in Oa×Or and 79.65%bivalents in Om×Oa involved allosyndetic association,which indicates that recombination and introgression should be possible if viable backcrosses can be recovered even from triploid hybrids.In this study,we revealed that the meiotic disturbance due to low affinities between parental genomes is the major reason for the sterility of these two triploid interspecific hybrids.The two hybrids showing vigor in reproductive growth are potential genetic resources in future breeding programs.A better understanding of genomic affinities between these distant Oryza species can facilitate planning an effective breeding program by using wide hybridization,and efficient and routine GISH analysis is helpful to monitor alien introgression in the process.     

基因组原位杂交辨别芸薹属异源四倍体AA、BB、CC基因组研究

利用基因组原位杂交（GISH）技术，以标记的白菜型油菜（AA，2n=20)的基因组总DNA）为探针，分别同芥菜型油菜（AABB，23n=36）和甘蓝型油菜（AACC，2n=38)的中期染色体和间期核杂交，结果芥菜型油菜有20条染色体表现大而明亮的杂交信号，其它染色体上信号很弱或无，可以区分A、B基因组，甘蓝型油菜染体上表现有38个信号，A、C基因组不能分区分开来。以黑芥（BB,2n=16）的基因组总DNA为探针与埃塞俄比亚芥（BBCC，2n=34）的中期染色体和间期核杂交，16条染色体上显示明显的杂交信号，其它染色体上信号很弱，说明在长期的进化过程中，芸薹属中BB与AA和CC基因组间分化程度较大，而AA与CC基因组分化较小，基因组原位杂交表明最强的信号多集中分布于着丝粒区，本文讨论了这种分布的可能原因。     

植物异源多倍体中特定染色体组的剥离与重建

由于异源多倍体物种的进化时间久远,难以知晓确切的二倍体亲本,现在推测的自然界现存二倍体种又经历过独立的演化,因此,通过特定的实验方法从天然的异源多倍体物种中剥离出特定染色体组并重建异源多倍体的基本种,将为研究异源多倍化过程中祖先基因组的遗传与互作提供独特的材料。现已通过不同的杂交策略,从异源六倍体普通小麦和异源四倍体种甘蓝型油菜中成功重建它们的一个基本种。例如以人工合成的芸薹属异源六倍体（如埃塞俄比亚芥与白菜杂交的AA.BBCC)为桥梁,其中的C染色体组被选择性的丢失后产生的芥菜型油菜（AA.BB）与埃塞俄比亚芥杂交形成的杂种（BBAC）自交后便可重建黑芥(BB)祖先种;将四倍体与二倍体种之一杂交后形成的同源异源六倍体（如AAAACC）连续自交,使处于同源四倍体状态的染色体组（A）快速丢失而重建另一个二倍体基本种（CC）。