Karyotype Analysis of Speirantha gardenii (Hook.) Baill.

This paper reports the chromosome numbers and karyotype analysis of Speirantha gardenii, which is endemic to China. The material was collected from Huang Shan, Anhui. It is a diploid species. Its somatic chromosome is 2n=38=22m+6sm+10st. The 9th pair is submedian centromere chromosomes, but it has two constrictions. The secondary constriction is on the short arm near centromere. Of the 19 chromosome pairs,secondary constriction is present only in this pair.     

Retroelement genome painting: cytological visualization of retroelement expansions in the genera Zea and Tripsacum

Divergence of abundant genomic elements among the Zea and Tripsacum genera was examined cytologically and a tool kit established for subsequent studies. The LTR regions from the CRM, Huck, Grande, Prem1, Prem2/Ji, Opie, Cinful-1, and Tekay retroelement families were used as FISH probes on mitotic chromosome spreads from a "trispecies" hybrid containing chromosomes from each of three species: Zea mays (2n = 20), Z. diploperennis (2n = 20), and Tripsacum dactyloides (2n = 36). Except for Tekay, which painted both Zea and Tripsacum chromosomes with nearly equal intensity, the retroelement probes hybridized strongly to the Zea chromosomes, allowing them to be distinguished from those of Tripsacum. Huck and Grande hybridized more intensely to maize than to Z. diploperennis chromosomes. Tripsacum genomic clones containing retroelement sequences were isolated that specifically paint Tripsacum chromosomes. The retroelement paints proved effective for distinguishing different genomes in interspecific hybrids and visualizing alien chromatin from T. dactyloides introgressed into maize lines. Other FISH probes (180-bp knob, TR-1, 5S, NOR, Cent4, CentC, rp1, rp3, and alpha-ZeinA) could be simultaneously visualized with the retroelement probes, emphasizing the value of the retroelement probes for cytogenetic studies of Zea and Tripsacum.     

Cytogenetic analysis of three species of the genus <Emphasis Type="Italic">Haemulon</Emphasis> (Teleostei: Haemulinae) from Margarita Island,Venezuela

This paper describes the karyotype analysis of Haemulon aurolineatum, Haemulon bonariensis and Haemulon plumierii, by Giemsa staining, C-banding, Ag-staining and fluorescent in situ hybridization (FISH), to locate the 18S and 5S rRNA genes. Diploid modal count in the three species was 2n = 48 acrocentric elements. Except for pair 24, which exhibited an unmistakable secondary constriction in all three species, it was not possible to classify them as homologous to each other because differences in chromosome size were too slight between adjacent pairs within a size-graded series. Ag-NOR clusters were located in pair 24 in the three species with signal located on the secondary constriction of these chromosomes. C-banding demonstrated that the three species share the same distribution pattern of the constitutive heterochromatin with centromeric heterochromatic blocks in the 23 chromosome pairs and a pericentromeric block in pair 24 which is coincident with the NORs. FISH experiments showed that 18S rDNA sequences were located coincident with the Ag-NOR site in the three species; however, differences in both the number and chromosome distribution of 5S-rDNA cluster were detected among them. Our data suggest that chromosome evolution of Haemulon has been preserved from major changes in the karyotypic macrostructure, whereas microstructural changes have occurred.     

The chromosomes ofCunninghamia konishii,C. lanceolata,andTaiwania cryptomerioides (Taxodiaceae)

Karyotype analyses were conducted onCunninghamia konishii, Cunninghamia lanceolata, andTaiwania cryptomerioides, all members ofTaxodiaceae. The somatic chromosome number was found to be 2n = 2x = 22 in all species which concurrs with previous reports. The karyotypes are generally asymmetrical with the smaller chromosomes being more submedian than the larger ones. Chromosomes with unusual or specific structures, thought to be associated with the nucleolar organizing region, were found in each species.Cunninghamia species have a marker chromosome pair with an unusually long secondary constriction.Taiwania has an unusually long kinetochore region present in a submedian chromosome pair.     

Chromosomal studies on five species of the genus Leptodactylus Fitzinger, 1826 (Amphibia, Anura) using differential staining

Cytogenetic studies were carried out on five species of Leptodactylus, namely L. fuscus, L. notoaktites, L. labyrinthicus, L. ocellatus, and L. podicipinus, after standard staining, Ag-NOR and C-banding as well as BrdU incorporation for three of them. The species had 2n = 22 chromosomes and two basic karyotype patterns. Chromosome 8 was a marker bearing a secondary constriction. In all species, this secondary constriction corresponded to the Ag-NOR site. The species had centromeric C-bands in all chromosomes of the complement, but some interstitial or telomeric bands seemed to differentiate some karyotypes, either at the species or the population level. In L. ocellatus, the C-banding pattern confirmed the occurrence of a heteromorphic pericentric inversion in chromosome 8 in specimens from one of the populations. The BrdU incorporation technique showed no detectable difference in the replication patterns of the major bands in the chromosomes of L. notoaktites, L. labyrinthicus, and L. ocellatus.     

Chromosome evolution in kangaroos (Marsupialia: Macropodidae): cross species chromosome painting between the tammar wallaby and rock wallaby spp. with the 2n = 22 ancestral macropodid karyotype.

Marsupial mammals show extraordinary karyotype stability, with 2n = 14 considered ancestral. However, macropodid marsupials (kangaroos and wallabies) exhibit a considerable variety of karyotypes, with a hypothesised ancestral karyotype of 2n = 22. Speciation and karyotypic diversity in rock wallabies (Petrogale) is exceptional. We used cross species chromosome painting to examine the chromosome evolution between the tammar wallaby (2n = 16) and three 2n = 22 rock wallaby species groups with the putative ancestral karyotype. Hybridization of chromosome paints prepared from flow sorted chromosomes of the tammar wallaby to Petrogale spp., showed that this ancestral karyotype is largely conserved among 2n = 22 rock wallaby species, and confirmed the identity of ancestral chromosomes which fused to produce the bi-armed chromosomes of the 2n = 16 tammar wallaby. These results illustrate the fission-fusion process of karyotype evolution characteristic of the kangaroo group.     

草芍药,野牡丹和黄牡丹的核型研究

本文报道了国产芍药属(Paeonia L.)植物草芍药、野牡丹和黄牡丹的染色体数目及核型,均为2n=10=6m 2sm 2st,它们分别具2、3和4对次缢痕,所具次缢痕的数目和位置可以作三种核型的区别特征。     

Karyological Study on the Endangered Species Camellia azalea (Theaceae)

The chromosome number and karyotype of Camellia azalea were reported here for the first time . The species showed in somatic cells the round prochromosome type of the interphase nuclei and the interstitial type of the prophase chromosomes. It was a diploid , and the karyotype could be formulated as 2n = 2x = 30 = 28m (1SAT ) + 2sm, belonging to Stebbins’1B type. The third, fourth, ninth, tenth, eleventh and twelfth chromosomes had secondary constriction respectively, and one satellite had been found on the fifteenth chromosome. The cytological results supported the suggestion that C. azalea was primitive species in Sect . Camellia of the genus Camellia. A clue on selecting parents was also proposed due to the chromosome numbers and the position in Sect. Camellia.     

Chromosomal localization of the 18S-28S and 5S rRNA genes and (TTAGGG)n sequences of butterfly lizards (Leiolepis belliana belliana and Leiolepis boehmei, Agamidae, Squamata)

Chromosomal mapping of the butterfly lizards Leiolepis belliana belliana and L. boehmei was done using the 18S-28S and 5S rRNA genes and telomeric (TTAGGG)n sequences. The karyotype of L. b. belliana was 2n = 36, whereas that of L. boehmei was 2n = 34. The 18S-28S rRNA genes were located at the secondary constriction of the long arm of chromosome 1, while the 5S rRNA genes were found in the pericentromeric region of chromosome 6 in both species. Hybridization signals for the (TTAGGG)n sequence were observed at the telomeric ends of all chromosomes, as well as interstitially at the same position as the 18S-28S rRNA genes in L. boehmei. This finding suggests that in L. boehmei telomere-to-telomere fusion probably occurred between chromosome 1 and a microchromosome where the 18S-28S rRNA genes were located or, alternatively, at the secondary constriction of chromosome 1. The absence of telomeric sequence signals in chromosome 1 of L. b. belliana suggested that its chromosomes may have only a few copies of the (TTAGGG)n sequence or that there may have been a gradual loss of the repeat sequences during chromosomal evolution.     

濒危植物杜鹃红山茶的细胞学研究

报道了杜鹃红山茶(Camellia azalea)的细胞学资料。其间期核为球形前染色体型,有丝分裂前期染色体为中间型。核型公式为2n=2x=30=28m(1SAT) 2sm,核型类型属于Stebbins的1B型。第3、4、9、10、11、12条染色体的长臂上具有次缢痕,第15条染色体的短臂上具随体。细胞学证据支持杜鹃红山茶在山茶组中较为原始的推断,并为人工杂交育种时亲本的选择提出了一些建议。     

Evidence for chromosome number reduction and chromosomal homosequentiality in the 24-chromosome Korean frog Rana dybowskii and related species

The karyotype of the Korean frog Rana dybowskii with its pattern of C-band heterochromatin distribution was numerically analyzed. There are 2n = 24 chromosomes in the karyotype representing a reduction in number from the typical 2n = 26 chromosome karyotype of Rana. The karyotype shows other evidence of reorganization relative to 26-chromosome species. The chromosomes grade smoothly in size from largest to smallest without the two size classes that are characteristic for 26-chromosome species. In contrast to many 26-chromosome species, there are few centromeric C-bands but many interstitial ones. C-bands for each homologous chromosome pair are distinctive. A prominent secondary constriction is located on one of the smallest chromosomes, chromosome 11, in a position similar to that seen in most 26-chromosome species. The karyotype of R. dybowskii is compared to those of other species of Rana known to have 2n = 24 chromosomes; it is most similar to that of R. chensinensis, less so that of R. ornativentris and less still to that of R. arvalis in terms of the positions of centromeres and secondary constrictions. C-bands as well as secondary constrictions in the karyotypes of these frogs show evidence of chromosomal homosequentiality. The process and possible consequences of chromosome number reduction from an ancestral 26-chromosome karyotype is also evident in the karyotypes of these closely allied palearctic frogs. Pericentric inversions followed by fusion of two small elements apparently produced a new chromosome, chromosome 6, occurring originally among northeast Asian populations.     

三尖叶猪屎豆染色体核型分析

本文以三尖叶猪屎豆(Crotalaria anagyroides H.B.K)根尖为试验材料,对其染色体核型及数目进行了研究。研究结果表明:三尖叶猪屎豆体细胞染色体数目为2n=16。染色体组总长度为26.62微米,全部的染色体为中部着丝点,除在第8对染色体上发现有一随体外,其余均没有发现随体和次缢痕。按Levan的染色体分类标准,其染色体核型组成是K(2n)=16=14m+2m_8~(sat)。     

青海四种雏蝗染色体核型的比较分析

采用常规染色体制片方法对雏蝗属的褐色雏蝗Chorthippusbrunneus(Thunb .) ,异色雏蝗C .big uttulus(Linnaeus) ,小翅雏蝗C .fallax(Zub .) ,青藏雏蝗C .qingzangensis(Ying)的染色体核型进行分析 ,结果 :染色体数目均为 2n(♂ ) =1 7=1 6+XO ;常染色体类型为两类 ,中着丝点染色体 (m ,6条 )和端着丝点染色体 (T ,1 0条 ) ;性染色体类型为端着丝点。褐色雏蝗、异色雏蝗和青藏雏蝗的核型公式和染色体的相对长度组成为K( 2n ,♂ ) =1 7=6m +1 1T =6L +6M +4S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +6M +4S +XX ;小翅雏蝗的为K( 2n,♂ ) =1 7=6m +1 1T =6L +4M +6S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +4M +6S+XX。褐色雏蝗性染色体中部有次缢痕。染色体臂数 4种均为NF =2 3(♂ ) ,2 4 (♀ )。     

Apomixis in Tripsacum: comparative mapping of a multigene phenomenon.

A relationship has been established between the expression of apomixis in natural polyploids of Tripsacum dactyloides and fertility as measured by percent seed set. Thus, fertility may be reliably used as a defining phenotype for apomixis when scoring the progeny from diploid (2n = 2x = 36) x tetraploid (2n = 4x = 72) crosses in Tripsacum. By exploiting the relationship between apomixis and fertility, as defined by seed set, analyses were performed on a set of related second-generation triploid populations segregating for apomixis. These populations were derived from sexual (diploid) x apomictic (tetraploid) crosses. Six out of 25 genome-dispersed restriction fragment length polymorphism (RFLP) markers co-segregate with fertility. Five of these markers were previously reported and include: php20855, tda48, tda53, umc62, and umc83, and are linked to Tripsacum genetic linkage groups F, I, H, L, and A, respectively. Significantly, we report here the syntenic relationships of the maize chromosome intervals to Tripsacum that segregate for numerous meiosis-specific and fertility-associated genes. Utilizing RFLP locus comparative mapping based on conservation of chromosome (genic) regions between related species, it may be concluded that the genes controlling fertility have been preserved in both Tripsacum and maize. A sixth marker, umc166, has also been shown to co-segregate with fertility and is conserved in both grass species. Specifically, umc166 is linked to Tripsacum linkage group D and, by syntenic comparison, to the short arm of maize chromosome 5. Encoded within this marked interval is the gene Ameiotic1 (Am1) whose function is required for the initiation of meiosis in both micro- and megaspore mother cells and whose absence of expression in the female is, in all likelihood, a prerequisite for the expression of apomixis.     

Chromosome evolution in the genus Mikania (Compositae)

Karyotypic analysis of ten species of the genus Mikania was carried out using Feulgen staining. Species belonging to the following sections were analyzed: Section Thyrsigerae containing M. additicia (2n = 34), M. hemisphaerica, M. lanuginosa, and M. punctata (2n = 36), and Mikania sericea (2n = 42), which adds a new basic chromosome number (x = 21) to the genus and to the tribe Eupatorieae; Section Corymbosae with M. hastato-cordata (2n = 34) and M. involucrata and M. microptera with 2n = 36 chromosomes; Section Spicato-Racemosae with M. sessilifolia, with 2n = 108 chromosomes. One unidentified species with 2n = 34 chromosomes was also analyzed. All the species studied show one large pair of chromosomes with a secondary constriction in the middle region of the long arm. The morphology of this chromosome suggests that it can be considered as a cytological marker for the genus. Because of the distinctive inflorescence types found in the genus Mikania and the high frequency of species with x = 18, a correlation between morphological and chromosomal evolution is discussed. The present study suggests that the basic original chromosome number for the genus is x = 18, from which the others (x = 17, 19, 20, 21) have been derived by aneuploidy to form the observed aneuploid series.     

Utilization of wild relatives in genetic improvement of Arachis hypogaea L.

Summary The chromosome complements of 12 taxa in section Arachis were karyotypically and meiotically analysed. In taxa with 2n=20 the arm ratio of the respective pair of chromosomes was taken as an independent quantitative character and statistically analysed by Mahalanobis D². Two clusters were formed, one represented solely by A. batizocoi and the other consisting of the remaining 11 taxa. This grouping was confirmed by canonical analysis. In the larger group of species, A villosa and A. correntina were closely related karyotypically and on D² distance, while A. cardenasii forms a distinct subgroup. A. cardenasii lacks the short A chromosome recorded in other species of this group, and A. batizocoi is no longer the only species to have a pair of chromosomes with a secondary constriction. The taxa with 2n=40, A. monticola and A. hypogaea, are karyotypically very similar, though there is a difference in the number of chromosome pairs with a secondary constriction. On the basis of karyomorphological affinity, especially in relation to marker chromosomes, A. cardenasii is probably one of the ancestors of the tetraploid species studied.Approved as ICRISAT Journal Article No. 169 and released for publication     

Karyomorphology of Taiwanese Begonia (Begoniaceae): taxonomic implications

The karyomorphology of all 14 species of Taiwanese Begonia was investigated to elucidate their chromosome features and chromosomal evolution. Among all species investigated, differences in chromosome features are found in: (1) chromosome number 2 n = 22, 26, 36, 38, 52, 60, 64, 82, and (2) frequencies of chromosomes with secondary, tertiary, and/or small constrictions of polyploids, ranging from 23% to 63%, which is higher than the expected value of about 9%. It is suggested that after polyploidization from the diploid species (i.e., 2 n = 22 and frequencies of chromosomes with secondary, tertiary, and/or small constrictions of polyploids of about 9%), chromosome translocations occurred, followed by a decrease in chromosome number, and subsequently stabilized genomes were formed in various species in Taiwan. The karyomorphological evidence also suggested that the chromosome morphology has evolved in parallel in the begonias belonging to different sections in Taiwan. The variation in chromosomal features is more complex than the variation in floral and fruit morphologies. Karyomorphological data also supports the recognition of five new species in Taiwan: Begonia bouffordii, B. chuyunshanensis, B. pinglinensis, B. tengchiana, and B. wutaiana. Based on detailed karyomorphological analyses, the taxonomic implications, speciation, and chromosomal evolution in Taiwanese Begoniaare discussed.     

中国特有的八角莲和六角莲的核型

本文研究了八角莲Dysosma versipellis(Hance)M.Cheng和六角莲Dysomapleiantha((Hance)Woodson的核型。二者的染色体数目均为2n=12,由四对具中部着丝点染色体、一对具近中部着丝点染色体和一对具端部着丝点染色体组成,各有一对染色体具有次缢痕,八角莲的次缢痕在第3对染色体的长臂上,六角莲的次缢痕在第1对染色体的短臂上。二者均属较对称的“2A”核型。但它们在染色体相对长度的变异幅度和差值、臂比的变异幅度和差值以及最长与最短染色体的比值上均有微小的差异。结果表明二者有密切的亲缘关系。演化趋势是八角莲→六角莲。八角莲的核型为首次报道。     

Reproduction of Meloidogyne marylandi and M. incognita on several Poaceae

The susceptibility of 22 plant species to Meloidogyne marylandi and M. incognita was examined in three greenhouse experiments. Inoculum of M. marylandi was eggs from cultures maintained on Zoysia matrella "Cavalier" or Cynodon dactylon x C. trasvaalensis "Tifdwarf". Inoculum of M. incognita was eggs from cultures maintained on Solanum lycopersicum 'Rutgers'. In each host test the inoculum density was 2,000 nematode eggs/pot. None of the three dicot species tested (Gossypium hirsutum, Arachis hypogaea, and S. lycopersicum) were hosts for M. marylandi but, as expected, M. incognita had high levels of reproduction on G. hirsutum and S. lycopersicum. Meloidogyne marylandi reproduced on all of the 19 grass species (Poaceae) tested but reproduction varied greatly (P = 0.05) among these hosts. The following grasses were identified for the first time as hosts for M. marylandi: Buchloe dactyloides (buffalograss), Echinochloa colona (jungle rice), Eragostis curvula (weeping lovegrass), Paspalum dilatatum (dallisgrass), P. notatum (bahiagrass), Sorghastrum, nutans (indiangrass), Tripsacum dactyloides (eastern gamagrass), and Zoysia matrella (zoysiagrass). No reproduction of M. incognita was observed on B. dactyloides, Cyndon dactylon (common bermudagrass), E. curvula, P. vaginatum (seashore paspalum), S. nutans, T. dactyloides, Z. matrella or Z. japonica. Reproduction of M. incognita was less than reproduction of M. marylandi on the other grass species, except for the Zea mays inbred line B73 on which M. incognita had greater reproduction than did M. marylandi (P = 0.05) and Stenotaphrum secundatum (St. Augustinegrass) on which M. incognita and M. marylandi had similar levels of reproduction.     

Assessment of genome organization among diploid species (2n = 2x = 14) belonging to primary and tertiary gene pools of pearl millet using fluorescent in situ hybridization with rDNA probes.

Two contrasting forms of Pennisetum belonging to the primary and tertiary gene pools were assessed for genomic organization using in situ hybridization with rDNA probes (18S-5.8S-25S and 5S) on metaphase and interphase cell nuclei. The primary gene pool is represented by diploid (2n = 2x = 14) cultivated pearl millet (Pennisetum glaucum) and its close wild relatives (Pennisetum violaceum and Pennisetum mollissimum). Pennisetum schweinfurthii (2n = 2x = 14) was taken as representative of the tertiary gene pool, owing to its diploid status and its similarity to the accessions of the primary gene pool in chromosome number. Using the 18S-5.8S-25S probe, we observed two sites of distribution in the four species but at different locations. Within the primary gene pool, signals were detected on the telomeric part of the short arm of chromosome pair VI and at the nucleolar organizing region (NOR) of the satellited chromosome pair (VII). Signals were observed at the NOR of the two satellited chromosome pairs (I and IV) of P. schweinfurthii. The 5S probe was detected at the telomeric part of the short arm of metacentric chromosome pair IV of the three species of the primary gene pool, while it occured in an intercalary position on the short arm of chromosome pair II of P. schweinfurthii. These results showed a chromosomal similarity of rDNA sequence locations within the primary gene pool and are in agreement with the high genetic identity between wild and cultivated forms of pearl millet previously revealed by allozyme studies. Implications of genomic organization for genetic resource enhancement are discussed. Key words : Pennisetum, in situ hybridization, rDNA probes, genomic organization.