青藏高原六种棘豆属植物的染色体数目及核型报道

对6种棘豆属植物（Oxytropis）的13个居群样进行细胞学研究,其中黄花棘豆（O．ochrocephala）、绢毛棘豆（O．tatarica）、甘肃棘豆（O．kansuensis）和铺地棘豆（0．humifusa）为首次报道染色体数目（2n=16）和核型;在胀果棘豆（O．stracheyana）中（2n=48）首次发现B染色体。现有的细胞学资料表明：棘豆属植物中多倍体占总报道数的58％,这说明多倍化在本属植物的进化过程中起着非常重要的作用,但青藏高原仅有一种植物发现多倍体,多倍化并不占主导地位,而主要表现为二倍体水平上的结构变异,即核型不对称性的变化。     

Chromosome Numbers and Karyotypes of Six Oxytropis Species (Fabaceae) from the Qinghai Tibetan Plateau,China

Chromosome numbers and karyotypes of 13 populations of six Oxytropis species (Fabaceae) from the Qinghai Tibetan Plateau, China, were presented. The chromosome numbers and karyotypes in O.ochrocephala, O.tatarica, O.kansuensis and O.humifusa (2n=16) were reported for the first time. B chromosomes were found from O.stracheyana (2n=48). The basic chromosome number of x=8 is confirmed for the genus. The available chromosomal data indicate that polyploidy may have played an important role in the evolution of the genus, with the incidence of polyploidy in the genus reaching 58%. However, our results indicated that among the populations here examined only one was a hexaploid with 2n=48. Such a chromosomal pattern indicates that the karyotypic repatterning at the diploid level seems to be the predominant feature of chromosomal evolution in the Oxytropis species from the Qinghai Tibetan Plateau, and that sympatric speciation via hybridization and polyploidization has played a minor role in the species diversification of the genus from this area.     

Chromosome diversity of South American Oxalis (Oxalidaceae)

Mitotic or meiotic chromosome studies are reported for 39 species or subspecies of Oxalis from South America belonging to 14 sections. Chromosome numbers of 34 of these taxa are reported for the first time. Diploids and polyploids with six different basic chromosome numbers x=5, 6, 7, 8, 9 and 11 are described. Thirteen species of subgenus lhamnoxys were analysed and two new basic chromosome numbers were observed in diploid entities of this subgenus, x = 6 and x=9. The underground stem-bearing entities of Oxalis subgenus Oxalis studied (in sections Articulatae, Jonoxalis and Palmatifoliae) are mostly diploids and polyploids with a basic chromosome number x=7. Five species of section Carnosa are diploids with x = 9. In species of sections Rosea, Ortgieseae, Clematodes and Laxae the basic chromosome numbers x = 6, 7, 8 and 9 were observed. Groups of related species sharing the same chromosome number are discussed with the aim of improving the infrageneric delimitation of the genus. The basic chromosome number x=6 seems to be primitive in the genus and other basic chromosome numbers probably appeared several times in the course of chromosome evolution of Oxalis .     

十二种沫蝉的染色体研究 (同翅目： 沫蝉总科)

观察了同翅目头喙亚目12种沫蝉雄性的染色体数目和减数分裂行为。通过对沫蝉总科现有核型资料的分析,认为沫蝉总科的核型特点是：①染色体较小,数目较多,总科内染色体数目变化范围较大,众数为2n=26（24+XO）;②染色体的易位现象极为普遍,因此可以推测,通过染色体的易位导致染色体数目增加是核型进化的主要机制;③减数分裂前期Ⅰ具有典型的花束期,但没有弥散期。因此从精子发生来看沫蝉总科与叶蝉总科、角蝉总科和蝉总科的关系更为密切,而与蜡蝉总科的关系较远。头喙亚目的亲缘关系可能是：蜡蝉总科+{蝉总科+［沫蝉总科+（叶蝉总科+角蝉总科）］}。     

Karyotype studies of some species of Dalechampia Plum. (Euphorbiaceae)

Karyotype studies in eight species of Dalechampia , including 10 natural populations, revealed chromosome numbers (2 n = 36, 46, 138 and 198) differing from two numbers cited in the literature (2 n = 44 and 72). The basic number x = 6, as in the genus Acalypha , may be considered ancestral in Dalechampia. Analysis of chromosome number, haploid chromosome length and karyotype symmetry suggests that the major chromosome mechanism acting in karyotype evolution of Dalechampia is polyploidy, but differences in chromosome morphology may be caused by chromosome rearrangements.     

Karyological studies on the Sino-Himalayan genus, Cremanthodiurn (Asteraceae: Senecioneae)

Twenty-two populations of seven species of Cremanthodium from high altitude regions of western China were observed karyologically. C. ellisii, C. microglossum, C. brunneo-pilosum, C. stenoglossum, C. discoideum and C. lineare all had the same chromosome number of 2 n = 58 whereas C. humile had 2 n = 60. All chromosome numbers of these species are documented here for the first time. The basic number of x = 30 is new for this genus. The karyotypes of all species belong to 2A type according to Stebbins' asymmetry classification of karyotypes. Two basic chromosome numbers, x = 30 and x = 29 in Cremanthodium , correspond exactly to two branching patterns in this genus, sympodial versus monopodial. The systematic and taxonomic statuses of the sympodial species need further study. The karyomorphological data provide no support to the sectional subdivision in Cremanthodium .     

八种国产大戟属植物的核型报道

8种大戟属Euphorbia L．植物的核型分析结果表明,大戟属不同亚属的染色体基数与其形态变 异的复杂性有一定关系。地锦草亚属subgen．Chamaesyce 3个种染色体基数分别为x=8,9,11;一品红 亚属subgen．Poinsettia两个种染色体基数均为x=7,分别为四倍体和八倍体;乳浆大戟亚属subgen． Esula 3个种,染色体基数分别为x=7,10,10。根据以前学者发表的资料分析,一品红亚属和大戟亚属 Subgen. Euphorbia的染色体基数是很稳定的,分别为x=7和x=10;通奶草E．hypericifolia为x=8 的四倍体,它不仅有染色体整倍性的变异,还有异基数性的变化。结合以前学者的研究,笔者支持x= 10为大戟属的最原始基数的观点。齿裂大戟E．dentata和通奶草具不同的染色体倍性,猫眼草E． esula的细胞染色体数目观察证实了我国存在四倍体的居群,与欧洲和北美的植物构成一个典型的多倍体复合体。     

Karyotypes of eight species of Euphorbia L. (Euphorbiaceae) from China

In this paper, eight species of the genus Euphorbia L. were cytologically studied. The three species of the subgenus Chamaesyce Raf., E. hirta, E. humifusa and E. hypericifolia, had chromosome numbers of 2n = 18, 22 and 32, with their basic chromosome numbers being x = 9, 11 and 8 respectively. The two species of the subgenus Poinsettia (Grah.) House. E. dentata, with 2n=28, a tetraploid, and E. cyathophora, with 2n= 56, a octoploid, had both the basic chromosome number of x= 7. The three species of the subgenus Esula Pers, E. lathyris, E. helioscopia and E. hylonoma, had chromosome number of 2n= 20, 42 and 20, with their basic numbers being x= 10, 7 and 10 respectively. The basic chromosome number of x = 8 is new for E. hypericifolia, in which x = 7 was previously reported. This indicates that this species had both ploidy(2n = 4x = 28, 8x = 56) and dysploidy(x = 7, 8) variations. In E. dentata, there occurred also ploidy variation (2n = 2x, 4x and 8x). A tetraploid cytotype of E. esula was found in China, its diploid cytotype and hexaploid cytotype being previously reported in North America, the Iberian Peninsula and some other European areas. Based on our results and those previously reported, we support the viewpoint that x＝10 may be the original basic chromosome number of Euphorbiaand discuss the role of polyploidy and dysploidy in the speciation and evolution of this genus     

Chromosome number of <Emphasis Type="Italic">Orthophytum</Emphasis> species (Bromeliaceae)

The genus Orthophytum Beer comprises 53 species, all narrow endemics to south-eastern and north-eastern Brazil. In this study we present meiotic and mitotic chromosome numbers of 12 species of this important genus in Bromeliaceae. For six of these taxa we are reporting the first cytogenetic study. Orthophytum albopictum, O. amoenum and O. burle-marxii presented 2n = 100 chromosomes and O. hatschbachii, O. mucugense, O. vagans, O. supthutii, O. zanonii and O. ophiuroides showed 2n = 50 chromosomes. These results are consistent with the proposed basic number of x = 25 for Bromeliaceae family. In the genus Orthophytum, polyploidy seems to play an important role in chromosome evolution associated with habitat differentiation among diploid and polyploid species.     

Karyotypic study of Echinops (Asteraceae) in Fars Province, Iran

A karyotypic study was performed on 19 Echinops species in Fars Province, Iran. The taxa revealed chromosome counts of 2 n = 28, 30, 32 and 34. Somatic chromosome numbers of 18 species are reported for the first time. Using somatic chromosome number as a criterion for section delimitation, the transfer of E. gedrosiacus, E. cyanocephalm and E. sojakii from Sect. Oligolepis to Sect. Ritropsis is suggested. Differences in basic chromosome numbers point towards the possible role played by centric fusion/fission in the karyotypic evolution of the genus. The Karl Pearson coefficient of correlation and principal components analysis indicated the occurrence of structural changes in chromosomes. The species occupied classes 1A, 2A & 2B of Stebbins' karyotype classification, indicating the presence of a primitive symmetrical karyotype in the genus.     

POLYPLOIDY,DYSPLOIDY, AND CHROMOSOME PAIRING IN ECHEVERIA (CRASSULACEAE) AND ITS HYBRIDS

The 140+ species of Echeveria have more than 50 gametic chromosome numbers, including every number from 12 through 34 and polyploids to n = ca. 260. With related genera, they comprise an immense comparium of 200+ species that have been interconnected in cultivation by hybrids. Some species with as many as 34 gametic chromosomes include none that can pair with each other, indicating that they are effectively diploid, but other species with fewer chromosomes test as tetraploids. Most diploid hybrids form multivalents, indicating that many translocations have rearranged segments of the chromosomes. Small, nonessential chromosomal remnants can be lost, lowering the number and suggesting that higher diploid numbers (n = 30–34) in the long dysploid series are older. These same numbers are basic to most other genera in the comparium (Pachyphytum, Graptopetalum, Sedum section Pachysedum), and many diploid intergeneric hybrids show very substantial chromosome pairing. Most polyploid hybrids here are fertile, even where the parents belong to different genera and have very different chromosome numbers. This seems possible only if corresponding chromosomes from a polyploid parent pair with each other preferentially, strong evidence for autopolyploidy. High diploid numbers here may represent old polyploids that have become diploidized by loss, mutation, or suppression of duplicate genes, but other evidence for this is lacking. Most species occur as small populations in unstable habitats in an area with a history of many rapid climatic and geological changes, presenting a model for rapid evolution.     

Chromosomal criteria and their phylogenetic implications in the genus Onobrychis Mill. sect. Lophobrychis (Leguminosae), with special reference to Egyptian species

Chromosome numbers and measurements were recorded in 22 individuals from six populations of six species of Onobrychis , including the Egyptian species and most representatives of section Lophobrychis . The basic number of chromosomes was either x = 7 or x = 8 and the chromosomes were medium to medium-small, ranging in length, from c . 1.6 μm to 2.6 μm. Two new ploidy levels were found, 2 n = 4 x = 28 in O. bobrovii Grossh. and 2 n = 4 x = 32 in O. pulchella Schrenk. The origin of the chromosome numbers, geographical distribution and evolution of the species were assessed. Comparison of the data with those in the literature revealed that the observed interspecific variability among section Lophobrychis can be useful in taxonomic delimitation and demonstrates a complexity of evolution between the diploid and polyploid species. Section Lophobrychis has a comparatively highly derived organization and can be considered as a heterogeneous unit in the genus Onobrychis .  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 409–414.     

13种21居群葱属植物的细胞分类学研究

采用常规压片法,对13种（含1变种）21居群葱属（Allium L.）植物进行了细胞分类学研究。结果表明：所研究类群的染色体基数为7、8和11,核型的类型为2A、2B和3A型,并且存在2倍体、3倍体和4倍体。主要讨论了葱属根茎组（Sect.Rhizirdium G.Don）部分类群的核型分化和进化机制,高山韭（A.sikkimense Baker）和多星韭（A.wallichii Kunth）的细胞地理学,以及B染色体的多态性及其在生境上的适应意义。最后在本研究的基础上,结合前人的细胞分类学研究结果,对葱属植物的核型进化形成了如下认识：（1）该属植物的原始染色体基数为8,其他基数的类群是由基数为8的类群进化而来的;（2）葱属植物在核型类型的进化上存在两条路线：基数为7的类群核型进化趋势为2A→2B→2C,而基数为8的类群的核型进化趋势为1A→2A→2B→2C;（3）多倍化是葱属植物进化的重要机制之一。     

CHROMOSOME NUMBERS IN THE GENUS ANTHURIUM

Chromosome numbers were determined for 63 Anthurium species. Thirty-eight of these were newly determined. Generally the present work confirmed existing chromosome counts when these were available for comparison. The most common somatic chromosome number found was 30, but counts ranged from 2n = 20 to 90. In a few instances conflicting counts were obtained. B chromosomes were found frequently in Sect. Cardiolonchium and varied in number from one to three. Four polyploid series were evident from all available counts: 20-40, 24-30-48-84, 28-56 and 30-60-90-ca 124. Most species were part of the polyploid complex based on 30. Although species were not observed with n = 5, 6 or 7, movement among the basic numbers was considered to have occurred at this level. The relationship among these basic numbers and n = 15 (x₂) is still obscure.     

秋枫属的染色体数目及其进化意义

对秋枫属两个种Bischofia javanica和B·polycarpa的体细胞进行了染色体计数研究。结果表明这两个种在形态学上虽然存在差异,如秋枫是圆椎花序,重阳木是总状花序,但染色体数目均为2n=196。同时,结合细胞学、形态学和生态学特点探讨了秋枫属的染色体基数,多倍化的起源及其演化意义。     

Contribution to the cytotaxonomy of Oryzopsis (Poaceae)

Meiotic studies were performed in twelve populations of four Oryzopsis species (O. pubiflora, O. lateralis, O. holciformis var. longiglomis and O. barbellata) to obtain data on the ploidy level and cytological evolution of the genus. The chromosome number 2n=2x=24 was revealed in all the species and populations studied. The present and other studies show the occurrence of two basic chromosome numbers in the genus, i.e. x=11 and x=12. Although Oryzopsis species and populations studied are diploid and are expected to form only bivalents in metaphase of meiosis‐I, quadrivalents were observed in O. pubiflora and O. lateralis, possibly due to the occurrence of heterozygote translocations. B‐chromosomes of 0–2 were observed in all species and populations studied. This is the first report of the occurrence of B‐chromosomes in the genus Oryzopsis. Several meiocytes showed the presence of double chromosome number in O. lateralis, and multipolar cells were observed in populations of O. barbellata, O. lateralis and O. holciformis var. longiglomis. The occurrence of large pollen grains (possibly unreduced) was observed along with smaller (normal) pollen grains in these species. Significant differences observed in chiasma frequency and distribution among studied species may be of use in species delimitation. The Kakan population differed significantly from the other populations of O. lateralis in meiotic characteristics. If such cytological differences are accompanied by morphological variation (under investigation), we may consider this population as a new variety or subspecies.     

半蒴苣苔属植物染色体制片优化及染色体数目和倍性研究

染色体数目和倍性是系统与进化生物学和遗传学研究中十分重要的基础信息。为探索半蒴苣苔属染色体制片的适宜条件以及染色体数目的进化模式及其与物种的进化关系，该研究基于半蒴苣苔属染色体数目的进化历史，并根据该属植物具有叶片扦插繁殖的特性，采用叶片水培生根法获取半蒴苣苔(Hemiboea subcapitata)、弄岗半蒴苣苔(H.longgangensis)、龙州半蒴苣苔(H.longzhouensis)、江西半蒴苣苔(H.subacaulis var.jiangxiensis)、华南半蒴苣苔(H.follicularis)和永福半蒴苣苔(H.yongfuensis)6种植物的根尖材料，分析不同实验条件对染色体制片效果的影响，对染色体制片实验的条件进行优化及染色体计数，结果表明：(1)9:30—10:00取材，解离10 min以及染色15 min为半蒴苣苔属染色体制片的适宜条件。(2)上述6种半蒴苣苔属植物均为二倍体，染色体数目均为32(2n=2x=32)。(3)除个别物种染色体数目有变化以外，该属大部分物种染色体数目可能为2n=2x=32且染色体数目变化可能是非整倍化的作用，与物种进化没有明...     

Observations of Chromosomes of Malus Species in China

Somatic chromosome numbers of 37 forms (representing 22 species) of apples in China were counted using wall-degradation and hypotonic method. Among the species investigated 3 categories of chromosome numbers, i.e. 2n=34, 51 and 68 are confirmed. The chromosome numbers of the following species are here first reported: Malus ombrophila 2n= 34, M. prattii 2n=34, M. melliana 2n=34, Zhaojiaohonghua (M. sp.) 2n=34, and M. asiatica var. 2n=68. Polyploids (including infraspecific polyploids) account for 41% of the total number of the species investigated. 51 is a predominant number. It is suggested that ploidy variation is an important pathway in apple evolution in China, and triploid may be considered as a suitable evolution grade. There are rich apple germplasm resources in China. The systematic studies of this genus are obviously essential.     

中国水韭属植物的染色体数目及其分类学意义

利用细胞学方法观察统计了中国4种水韭属Isoestes植物的染色体数目。结果发现4个种的染色体基数均为x=11,其中高寒水韭I．hypsophila Hand.-Mazz．为2n=22,为首次报道;台湾水韭 I．taiwanensis DeVol为2n=22;中华水韭I．sinensis Palmer 2n=44为四倍体;而产于云南贵州一带并一直被当作是宽叶水韭I．japonica A．Br．的水韭属植物2n=22,与文献报道的宽叶水韭(2n=66,67,77,87,88,89)完全不同,应重新予以认识和评价。依据本文和其他相关的研究结果,对东亚水韭属植物进行了分类处理。     

兰花蕉属植物染色体新计数

首次报道了国产兰花蕉属植物2种1变种的体细胞染色体计数,其中兰花蕉及其变种长萼兰花蕉为2n=54,为六倍体;海南兰花蕉为2n=18,为二倍体。分析了世界范围内兰花蕉属植物染色体数及其倍性的地理学关系。