Chromosome number variation in the polyploid Cerastium alpinum-C. arcticum complex (Caryophyllaceae)

Chromosome numbers of Cerastium alpinum, C. arcticum , and C. nigrescens were studied from the main part of their distribution area. No chromosome number variation was found within C. alpinum , which seems to be octoploid throughout its range. Dodecaploid chromosome numbers (2n = 108) were found in both C. arcticum and C. nigrescens. A higher, possibly aneuploid, chromosome number was reported for plants from Southwest Greenland, and the intermediate chromosome number of 2n = 90 was found in potential hybrids between C. alpinum and C. nigrescens. Despite sporadic reports of deviating chromosome numbers, the chromosome number variation within the C. alpinum-C. arcticum complex seems to be restricted mainly to the octo- and dodecaploid levels.     

Taxonomic features ofSesleria calabrica (Poaceae), a neglected species from southern Italy

A taxonomic study of theSesleria juncifolia complex in the Italian Peninsula is presented, with a focus on southern Italian populations here named asSesleria calabrica (Deyl)Di Pietro comb. nov. et stat. nov. Karylological, morphological and anatomical characters were used for comparative analyses with populations of closely related species, such asS. juncifolia Suffren andSesleria apennina Ujhelyi occurring in the Italian Peninsula. Multivariate and univariate morphometric analyses, and qualitative morphological characters showed a distinct position ofS. calabrica. Populations ofS. calabrica differ in respect to various morphological characters of leaf and spikelet, such as the glume, lemma and palea length, stem length, the leaf sheath, leaf width, leaf thickness, and the total number of vascular bundles. Furthermore, previous karyological studies demonstrated that all the populations of bothS. juncifolia andS. apennina examined are octopolid (2n=8x=56), whereasS. calabrica was found to be dodecaploid (2n=12x=84).S. calabrica is strictly confined to the Pollino massif and the Orsomarso mountains in southern Italy, which represent the southernmost limit of theSesleria juncifolia complex distribution area both in Italy and in Europe. In addition toS. juncifolia andS. calabrica, the recognition ofS. apennina as a taxon distinct fromS. juncifolia is supported, at least for the area of the Apuan Alps.     

A new cytotype of Jacobaea vulgaris (Asteraceae): frequency,morphology and origin

Jacobaea vulgaris subsp. vulgaris (syn. Senecio jacobaea subsp. jacobaea) constitutes an intricate polyploid complex distributed in Europe. Four cytotypes have been reported in this species, three with euploid (diploid, tetraploid and octoploid; 2n=20, 40 and 80) and one with aneuploid (2n=32) chromosome numbers. Here we report that the diploid chromosome number (2n=20) reported from Bulgaria is due to misidentification with Jacobaea aquatica. On the other hand, we have discovered a new, hexaploid (2n=6x=60) cytotype within J. vulgaris subsp. vulgaris using flow cytometry. The new cytotype occurs within four sympatric populations of otherwise tetraploid and octoploid plants in Pannonia (one locality in the eastern Czech Republic and two localities in southwestern Slovakia) and in Podillya (one locality in western Ukraine). The frequency of hexaploid individuals within 76 studied populations is very low (only 10 of 693 analysed plants), and hexaploids probably represent hybrids between tetraploid and octoploid plants. Three mixed populations with hexaploid plants were subjected to detailed morphological and pollen fertility analyses. Multivariate morphometric analysis reveals partial separation of tetraploid and octoploid plants, whereas hexaploid individuals are similar in morphology to octoploids. In comparison with tetraploids, octoploids and hexaploids exhibit slightly longer ray florets, involucral bracts and tubular florets and more hairy outer achenes. Hexaploid plants display larger pollen grains and lower pollen fertility compared to tetraploids and octoploids.     

Decaploidy in Fragaria iturupensis (Rosaceae)

The strawberry genus, Fragaria (Rosaceae), has a base chromosome number of x = 7. Cultivated strawberries (F. ×ananassa nothosubsp. ananassa) are octoploid (2n = 8x = 56) and first hybridized from F. chiloensis subsp. chiloensis forma chiloensis × F. virginiana subsp. virginiana. Europe has no known native octoploid species, and only one Asian octoploid species has been reported: F. iturupensis, from Iturup Island. Our objective was to examine the chromosomes of F. iturupensis. Ploidy levels of wild strawberry species, include diploid (2n = 2x = 14), tetraploid (2n = 4x = 28), pentaploid (2n = 5x = 35), hexaploid (2n = 6x = 42), octoploid (2n = 8x = 56), and nonaploid (2n = 9x = 63). Artificial triploid (2n = 3x = 21), tetraploid, pentaploid, octoploid, decaploid (2n = 10x = 70), 16-ploid, and 32-ploid plants have been constructed and cultivated. Surprisingly, chromosome counts and flow cytometry revealed that F. iturupensis includes natural decaploid genotypes with 2n = 10x = 70 chromosomes. This report is the first of a naturally occurring decaploid strawberry species. Further research on F. iturupensis and exploration on northern Pacific islands is warranted to ascertain the phylogeny and development of American octoploid species.     

青海青甘韭9个居群的核型

本文研究了青海葱属青甘韭 9个居群的染色体数目和核型。其中分布于湟源、西宁和共和海拔相对较低的地区的居群为 2倍体 ,核型公式为 2n =2x =16 =14m 2st (2SAT) (湟源居群和西宁居群 ) ,2n =2x =16 =12m 2sm 2st (2SAT) (共和居群 ) ;分布于玛沁、玉树、囊谦等高海拔地区的居群为 4倍体 ,核型公式为 2n =4x =32 =2 8m 4st (2SAT) (玉树居群 1和囊谦居群 1) ,2n =4x =32 =2 4m 4sm 4st (玛沁居群和玉树居群 3)和 2n =4x =32 =2 6m 2sm 4st (玉树居群 2 ) ;囊谦一个生长在林下的居群为 8倍体 ,2n =8x =6 4 =54m 2sm 8st。讨论了居群间的核型分化和倍性与分布的关系。     

The Biology of Allium monanthum (Liliaceae) I. Polyploid Complex and Variations in Karyotype

Abstract Plants of Allium monanthum Maxim., whose gender expression are usually dioecious, but rarely hermaphrodite or gynomonoecious, proved to constitute a polyploid complex, consisting of diploid, triploid, and tetraploid individuals. The basic chromosome complement of this species consists of seven metacentric or submetacentric chromosomes and one acrocentric, the latter possessing a satellite on the short arm. Thus, the karyotype formula is expressed as 7V+11 (x=8). The diploid plants (2n = 16) were confined to central Honshu, Japan. Typical female plants possessed the standard karyotype, whereas male plants were heterozygous for two kinds of translocations. The 3x plants (2n=24) are somewhat widely distributed in the areas from the Kanto to Hokuriku district in Honshu. All female triploid plants possessed the standard karyotype. The geographical distribution of 4x plants (2n=32) which express mostly a female phenotype occurred nearly throughout the whole areas investigated; they are geographically isolated from the 2x plants. A majority of 4x plants had the standard karyotype. The remaining tetraploids were of the aberrant type, 4x/51, which has five acrocentric chromosomes, and two aneuploids 4x+1 and 4x-1. Both 3x and 4x forms seem to be of autopolyploid origin. Three kinds of aberrant nucleolar chromosomes with an extra satellite or an inseried secondary constriction were found in the heterozygotes for translocations of 2x plants and also in some plants of the 3x form. These aberrant plants usually form their own homogeneous populations, but were somewhat scattered throughout the range in their distribution. Thus, these individuals are considered to have perpetuated these types of chromosome aberrations which originated in the remote past.     

Morphometric and karyological analysis of a population ofSesleria sadleriana Janka in the Biele Karpaty Mountains (Slovakia)

Morphometric and karyological analysis was employed to prove the occurrence of a population ofSesleria sadleriana Janka, at the locality “Vr?atec” in the Biele Karpaty Mts. (Slovakia). Morphological characters of this population were analysed statistically (ANOVA, PCA) and compared with those of a population ofS. sadleriana in Austria (Hainburg an der Donau) and a population ofS. albicans Kit. exSchult. in the Czech Republic (Javo?í?ko). The two populations ofS. sadleriana did not differ from each other in the uppermost leaf length, spike length, glume length, lemma length, awn length of lemma and palea length. On the other hand, they differed significantly in these morphological characters from the population ofS. albicans. Karyological analysis demonstrated that both populations ofS. sadleriana consisted of octoploid plants (2n=8x=56). In addition to chromosome counting, flow cytometry was employed to screen ploidy levels. The experiment demonstrated a positive correlation between the ploidy estimated by chromosome counting and DNA flow cytometry inS. sadleriana andS. albicans. Flow cytometry proved extremely useful for ploidy screening in large numbers of plants. The locality “Vr?atec” represents the northernmost locality ofS. sadleriana known so far.     

The Asplenium aethiopicum complex in South Africa

BRAITHWAITE, A. F., 1986. The Asplenium aethiopicum complex in South Africa . Members of the complex in South Africa form an extensive polyploid series with three sexual and two apomictic cytotypes. The sexual tetraploid ( n = 72), octoploid ( n = 144) and dodecaploid ( n = 216) are described as Asplenium aethiopicum subsp. tripinnatum, A. aethiopicum subsp. aethiopicum and A. aethiopicum subsp. dodecaploideum respectively, and the apomictic octoploids ( 2n = 288) and decaploid ( 2n = 360) as A. aethiopicum subsp. filare , which is subdivided into apomicts pseudqfilare (8X), transvaalense (8 X) and capense (10 X). Comparison of their ecology and distribution suggests there is an increased tolerance to drier and cooler conditions with increase in level of polyploidy among the sexual subspecies and that the apomicts are tolerant of even more extreme conditions. The natural hexaploid hybrid between A. aethiopicum subsp. aethiopicum and A. aethiopicum subsp. tripinnatum is described and its meiotic pairing analysed. The numerical structure of the polyploid series in Africa generally suggests the complex represents a secondary polyploid cycle based on a genome of 72 chromosomes, and the unequivocal antosyndesis between the genomes of A. aethiopicum subsp. aethiopicum shown by the chromosome pairing in the hexaploid hybrids suggests the octoploid is either a segmental allopolyploid or autopolyploid. While it can be concluded from the morphology and cytology of A aethiopicum subsp. filare that the apomicts have arisen more than once, their precise mode of origin is unknown, although there is good evidence in at least one case for suggesting a hybrid origin.     

Cytogeographic Distribution and Genome Size Variation in Prairie Cordgrass (Spartina pectinata Bosc ex Link)

Prairie cordgrass plants (Spartina pectinata Bosc ex Link) were examined from 61 locations representing the geographic distribution of prairie cordgrass in the U.S. Using flow cytometry, the genome size of 183 individual plants of prairie cordgrass was determined, and the chromosome counts were obtained. Three distinct ploidy levels were observed: tetraploid ( $ \overline x = {1}.{56} {\text{pg}},{2}n = {4} \times = {4}0 $ ), hexaploid ( $ \overline x { = 2}.{33} {\text{pg}},{2}n = {6} \times = {6}0 $ ), and octoploid ( $ \overline {\text{x}} { = 3}.0{6} {\text{pg}},{2}n = {8} \times { = 8}0 $ ). In the sampled areas, the tetraploid populations extended from the East North Central to the New England regions of the U.S., while the octoploid cytotypes were mostly distributed in the West North Central regions. Populations of the tetraploids and octoploids were found in close proximity in the West North Central (Iowa and Kansas) and the West South Central (Oklahoma) regions. The hexaploid cytotype was found in one mixed population (4x?+?6x) occurring in Illinois. No statistically significant intraploidy genome size variation was found in the tetraploid populations, while significant intraploidy genome size variation was found in the octoploid populations. This study precisely defined the geographic distribution of cytotypes in prairie cordgrass throughout the different regions of the U.S. These results provide critical genome size and ploidy distribution information needed to design efficient breeding schemes for high yielding cultivars of prairie cordgrass with local adaption.     

Gamete composition and chromosome variation in pollen-derived plants from octoploid triticale x common wheat hybrids

Summary Anther culture of secondary octoploid triticale (AABBDDRR) and F₁ hybrids (AABBDDR) of octoploid triticale x common wheat crosses was carried out, and 96 pollen-derived plants were developed and studied cytologically. In addition to the 8 types of pollen-derived plants with the theoretically predicted chromosome number, plants with the chromosome constitutions of 2n = 38, 43, 45, 47, 74, and mixoploids were obtained. The haploids and the diploids had different distributions. The frequencies of plants with one and two (pairs of) rye chromosomes were extremely high, and anther culture may be an expeditious route for creating alien addition lines of distant hybrid F₁s. Chromosome aberrations, including deletions, inversions, translocations, as well as isochromosomes and ring chromosomes, were observed in some plants. Abnormal meioses, such as chromosome non-disjunction, were also found. The reasons for the chromosome aberrations are discussed.     

Chromosome polymorphism of thePoa macrocalyx complex in Hokkaido

A chromosome survey ofPoa macrocalyx growing on the coast of Hokkaido was carried out. Counts were made for 619 samples collected from 37 populations. A large variation in the chromosome numbers (2n=42-2n=87) was disclosed, and on the basis of this and some other observations, this species was presumed to represent an apomictic polyploid complex. Three main cytotypes with 2n=42, 2n=49 and 2n=68 were discovered. They differed in their geographical distribution. Plants with 2n=70 and 2n=77 appeared to a considerable extent, but it could not be ascertained whether they were good “races”. Other plants with diverse chromosome numbers, and in some cases only ephemeral, were also sporadically detected. Infrapopulational variation was scarce in some populations while fairly common in some others. Uneven segregation of chromosomes at meiosis and the fusion of reduced and unreduced gametes seemed to be the main factors contributing to chromosome fluctuations within a population.     

Occurrence of tetraploid and octoploid cytotypes in Senecio jacobaea ssp. jacobaea (Asteraceae) in Pannonia and the Carpathians

Four different cytotypes have been reported for Senecio jacobaea L. ssp. jacobaea throughout Europe, with the most common occurrence of tetraploids (2 n  = 40). Here we present a survey of previously published chromosome number data on this subspecies and its geographical distribution, and focus on populations from Pannonia and the Carpathians. Two ploidy levels have been determined in the study area, using chromosome counting and flow cytometry: tetraploid (2 n  = 40) and octoploid (2 n  = 80). Fifty-one populations originating from Slovakia, Austria, the Czech Republic, Hungary, Ukraine and Romania have been analysed. Multivariate morphometric analyses have been performed on 39 populations to study morphological differentiation between these two cytotypes. Despite slight morphological tendencies expressed on the level of populations, tetraploid and octoploids cannot be reliably distinguished morphologically and they are not taxonomically classified formally here.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 153 , 231–242.     

Variation and geographical distribution of ploidy levels inPennisetum sectionBrevivalvula (Poaceae) in Burkina Faso,Benin and southern Niger

Pennisetum sect.Brevivalvula is a species complex characterized by polyploidy and apomixis. Ploidy level was assessed by DAPI-flow cytometry for 304 plants of the section, originating from Burkina Faso, Benin and southern Niger. The results were confirmed for 54 plants based on chromosome counts. The samples show four euploidy levels (with x = 9) distributed among five species:P. hordeoides (2n = 36, 54),P. pedicellatum (2n = 36, 45, 54),P. polystachion (2n = 18, 36, 45, 54),P. setosum (2n = 54), andP. subangustum (2n = 18, 36, 54). The geographical distribution of these ploidy levels seems related to major vegetation zones present in Africa. Diploid populations ofP. polystachion andP. subangustum were found in the Banfora area, in Burkina Faso.     

A cytotaxonomic study of theCalamagrostis purpurea —langsdorffii—canadensis complex in the lowlands of hokkaido

A chromosome survey of 278 individuals from 52 localities confirmed, that the principal components of theCalamagrostis purpurea—langsdorffi—canadensis complex in the lowlands of Hokkaido are tetraploid (2n=28) and octoploid (2n=56). A few hexploids (2n=42), were also found, but they may be either a triploid of the tetraploid plants or a hybrid between the tetraploid and octoploid plants. These hexaploids clearly differ in origin from the North American plants with 2n=42 which are generally placed underC. canadensis. The tetraploids and the octoploids are significantly different in pollen size but resemble each other in other morphological features and ecological requirements. These two races are also not disparate in distribution within Hokkaido. The tetraploids in Hokkaido are closely related to the tetraploids known in Alaska, and these tetraploid plants may be continuously distributed from Hokkaido to Alaska. The octoploids in Hokkaido have shown good pollen. They seem to have had a somewhat different course of evolution fromC. purpurea s. str. which principally reproduces in an apomictic manner.     

横断山区两种菊科植物的核型研究

对横断山区两种菊科植物圆齿狗娃花和细叶亚菊进行了染色体数目报道和核型研究,其中圆齿狗娃花为首次报道,2n=18=2x=18m(2SAT);而细叶亚菊的为新的染色体数目,2n=72=8x=56m+16sm,与之前报道的36不同。研究结果发现菊科植物这两个属在横断山及其它地区同时存在二倍体与多倍体。     

长萼堇菜多倍体复合体种群的分布格局研究

采用常规压片方法观察了长萼堇菜Viola inconspicua Blume多倍体复合体18个种群的染色体数目,发现其中4个种群的染色体为2n=4x=24,14个种群的染色体为2n=8x=48.讨论了长萼堇菜四倍体和八倍体种群的分布,并推测其可能的起源和造成目前分布格局的原因.     

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 Icelandic Populus tremula

Aspen ( Populus tremula ) from two locations in Iceland, representing the north and the east populations, were examined for its chromosome number. The plants all have diploid chromosome number (2n=2x=38), as with most other aspen populations of this species in Europe. No previous record of chromosome count on the Icelandic material is available. The significance of such chromosome study is discussed. — Flora Nordica Notes no. 22.     

Biosystematic study ofSedum L. SubgenusAizoon (Crassulaceae)

Variation in chromosome number and morphological characters ofSedum aizoon L. var.floribundum Nakai were investigated to analyze, correlations between them. Geographical variation in chromosome number was also examined. Chromosome numbers of 189 individuals from 55 localities were counted as 2n=32, 33, 34, 48, 61, 64, 78, 80, 84, 85, 88, 93, 94, 95, 96, 97 and 102. InSedum subgenusAizoon, which has the basic number of X=8, var.floribundum of the speciesaizoon showed a polyploid series from tetraploid to dodecaploid. Tetraploids were found most frequently in this variety. More than two chromosome numbers were found in all the populations with 2n=61 or more. Tetraploids were mainly distributed in the eastern part of Japan, and higher polyploids (higher than hexaploid level except octaploids) were distributed in the western part of Japan. Thirteen morphological characters were examined in 119 individuals belonging to 30 populations. The principal component analysis and the cluster analysis of these characters indicated that populations with similar chromosome numbers were not always morphologically similar. Ten morphotypes can be recognized based on the combination of chromosome number and morphological characters. ThusS. aizoon var.floribundum can be regarded as a polyploid-aneuploid complex.