Cytotaxonomy of Prenanthes faberi (Compositae–Cichorieae)

The generic placement of Prenanthes faberi Hemsl. (Compositae–Cichorieae) has long been a controversial matter. Recent molecular phylogenetic analyses indicate its inclusion in the genus Faberia Hemsl. The present cytological investigation shows that this species has a chromosome number of 2n = 34 and a fairly symmetric karyotype consisting of 26 median centromeric (m) and 8 submedian centromeric (sm) chromosomes varying in length between 1.72–4.20 μm. The karyological characters of P. faberi are remarkably consistent with those reported previously in species of Faberia. The transference of this species to Faberia is strongly supported.     

Duthieeae,a new tribe of grasses (Poaceae) identified among the early diverging lineages of subfamily Pooideae: molecular phylogenetics,morphological delineation,cytogenetics and biogeography

The phylogeny of Pooideae, one of the largest subfamilies of grasses, has been intensively studied during the past years. To investigate the early evolutionary splits in Pooideae we used a broad sample of genera with uncertain placement, some of which have not been studied in molecular phylogenetics before, complemented by representatives from other lineages of this subfamily. Morphological, cytogenetic and biogeographical analyses were added to the molecular sequence work on chloroplast matK–3’trnK and nuclear ITS. According to chloroplast DNA data, a new and well-supported lineage was identified among the early branches. It consisted of Phaenosperma and a larger group of genera encompassing Anisopogon, Danthoniastrum, Duthiea, Metcalfia, Pseudodanthonia (inclusion resting on ITS and morphology), Sinochasea and Stephanachne. Based on structural characters we suggest to keep Phaenosperma under the monotypic tribe Phaenospermateae and to accommodate the other genera under a new tribe Duthieeae, which is morphologically well-defined by synapomorphic spikelet features. Megalachne and Podophorus were not part of the early diverging Pooideae lineages but belong to the Aveneae/Poeae complex. Morphological characteristics of Duthieeae are discussed with respect especially to Stipeae and reveal consistent differences between both tribes. The genera of Duthieeae and the major lineages of Stipeae are keyed. A cytogenetic survey of exemplary taxa corroborates high chromosome base numbers as prevailing within the early diverging lineages of Pooideae, but chromosome sizes are more highly varied than previously reported. Ecogeographical analyses point to warm and humid conditions as the ancestral bioclimatic niche of Phaenosperma and Duthieeae, whereas adaptation to cold and drought occurred only in a part of Duthieeae but was obviously less successful than in the widespread and much more species-rich tribe Stipeae. The distribution of Duthieeae with species-poor or monotypic genera in mountains of the northern hemisphere and Anisopogon as an outlier in Australia suggests relict character.     

华南地区3种兔儿风属植物(菊科-帚菊木族)的细胞学研究

首次报道了华南地区兔儿风属(Ainsliaea DC.)(菊科-帚菊木族Asteraceae-Pertyeae)3种植物共4个居群的染色体数目和核型。其中长穗兔儿风(A.henryi Diels)的染色体数目为2n=24,核型公式为2n=16m+8sm;三脉兔儿风(A.trinervis Y.C.Tseng)的染色体数目为2n=26,核型公式为2n=16m+10sm;莲沱兔儿风(A.ramosa Hemsl.)2个居群的染色体数目均为2n=26,核型公式为2n=26=22m+4sm。所有居群的染色体由大到小逐渐变化,核型没有明显的二型性。这些结果表明兔儿风属植物确有x=12和x=13两个基数,其中x=13可能是该属的原始基数。     

Chromosomal evolution in Pleurothallidinae (Orchidaceae: Epidendroideae) with an emphasis on the genus Acianthera: chromosome numbers and heterochromatin

In this study, we analysed chromosome number variation and chromomycin A₃/4′,6‐diamidino‐2‐phenylindole (CMA/DAPI) banding patterns in 48 species belonging to 12 genera of subtribe Pleurothallidinae (Orchidaceae) in order to understand the chromosome evolution based on recent phylogenetic hypotheses and taxonomic treatments. All species had small chromosomes, with numbers ranging from 2n = 20 in two Specklinia spp. to 2n = 80 in an unidentified Octomeria sp. In Acianthera, the most highly represented genus in this study, a great diversity of chromosome number and pattern of fluorescent bands was observed, showing heterochromatin accumulation in Acianthera section Sicariae subsection Pectinatae. Interspecific ascending and, mainly, descending dysploidy were the main mechanisms of chromosome number evolution in subtribe Pleurothallidinae. For Pleurothallidinae, x = 20 is suggested as the basic chromosome number, the same suggested for the related subtribe Laeliinae and for the whole tribe Epidendreae. The Brazilian species of the mega‐genus Stelis had chromosomes with small amounts of heterochromatin and chromosome numbers based on x₂ = 16. These are generally divergent from those reported for Andean and Meso‐American species, but in agreement with the monophyletic hypothesis proposed for Stelis spp. with a Brazilian Atlantic distribution. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178 , 102–120.     

Karyomorphological studies onWoodwardia sensu lato of Japan

Karyomorphological comparisons were made of five species of JapaneseWoodwardia. There were no marked differences at interphase and prophase among the five species.Woodwardia japonica, W. prolifera, andW. unigemmata were diploid with 2n=68 and the formulas of their metaphase karyotypes uniformly 4m(median centromeric chromosomes)+12sm(submedian)+52(st+t)(subterminal and terminal).Woodwardia orientalis was tetraploid with 2n=136 and 8m+24sm+104(st+t), and the ratio of each chromosomal type to total complement was identical to that of three diploid species. These four species had several characteristics in common:x=34, the longest chromosome of sm, and a mean chromosome length over 3.0 μm. AlthoughWoodwardia orientalis showed some similarity toW. prolifera, it seems to be an allotetraploid which originated by chromosome doubling of a hybrid ofW. prolifera and a diploid species as yet karyomorphologically unknown.Woodwardia kempii was tetraploid with 2n=124 and 8m+24sm+92(st+t), and differed from the others in havingx=31, the longest chromosomes of t, and a mean chromosome length under 3.0 μm. This species has been classified as an independent genus,Chieniopteris, and our karyomorphological study supports this treatment.     

扇脉杓兰和无距虾脊兰的核型分析

为了解扇脉杓兰(Cypripedium japonicum Thunb.)和无距虾脊兰(Calanthe tsoongiana T. Tang et F. T. Wang)的核型,采用根尖压片法对扇脉杓兰和无距虾脊兰的染色体数目和核型进行了研究。结果表明,扇脉杓兰体细胞的染色体数为22,核型公式为2n=2x=22=16m+2sm+2st+2t,染色体相对长度组成为2n=22=2L+6M2+12M1+2S,核不对称系数为60.01%,核型分类为2B型;而无距虾脊兰体细胞的染色体数为40,核型公式为2n=2x=40=28m+10sm+2st,染色体相对长度组成为2n=40=8L+10M2+16M1+6S,核不对称系数为59.84%,核型分类为2B型;两者核型都较为对称。其中,无距虾脊兰的核型为首次报道。这为扇脉杓兰和无距虾脊兰的进化地位和种质保护提供了细胞学证据。     

Cytotaxonomy of Dubyaea glaucescens (Compositae–Cichorieae)

Recent molecular phylogenetic analyses indicate that Dubyaea glaucescens (Compositae–Cichorieae) should be transferred to the genus Faberia as F. glaucescens. Here, we present cytological evidence for this transfer. Dubyaea glaucescens comprises two ploidy levels, 2n = 34 (diploid) and 2n = 51 (triploid), making the basic chromosome number x = 17. The chromosomes vary in length from 5.82 μm to 2.11 μm, and the karyotypes are 2n = 20m + 14sm (3sat) for the diploid cytotype and 2n = 30m + 21sm (3sat) for the triploid cytotype. Karyological characters of D. glaucescens, including chromosome number, size, morphology, and karyotype asymmetry, all agree remarkably with those reported previously in Faberia, but are distinct from those in other species of Dubyaea. The transfer of D. glaucescens to Faberia is thus strongly corroborated.     

Karyotype analysis and DNA content in some species of Chrysolaena (Vernonieae,Asteraceae)

Cytogenetic characterization by karyotyping and determination of DNA content by flow cytometry of five species of Chrysolaena (Vernonieae, Asteraceae) was performed. This is the first study of nuclear DNA content realized in the genus. The 2C-values were compared with the ploidy level and the total karyotype length (TKL) of each species. Mitotic analysis revealed a base chromosome number x = 10 for all entities and different ploidy levels, from diploid (2n = 2x = 20) to octoploid (2n = 8x = 80). All species showed bimodal karyotypes composed of metacentric and submetacentric chromosomes. The average chromosome size (ML) varied from 1.86 μm to 2.70 μm, while the TKL ranged from 18.65 μm to 80.55 μm. The intrachromosomal asymmetry index (A₁) varied from 0.27 to 0.38, while the interchromosomal asymmetry index (A₂) ranged from 0.19 to 0.25. A new cytotype is reported for the first time for C. propinqua. Accessory chromosomes found in C. verbascifolia, C. cognata, C. flexuosa, and C. propinqua are also reported as new.     

Chromosome evolution in the Laurales based on analyses of original and published data

We present a summary of currently available chromosome information for all seven families in the order Laurales on the basis of original and previously published data and discuss the evolution of chromosomes in this order. Based on a total of 53 genera for which chromosome data were available, basic chromosome numbers appear consistent within families: x = 11 (Calycanthaceae); x = 22 (Atherospermataceae and Siparunaceae); x = 19 (Monimiaceae); and x = 12 and 15 (Lauraceae). The Hernandiaceae have diverse numbers: x = 15 (Gyrocarpoideae) and x = 18 and 20 (Hernandioideae). Karyotype analyses showed that Hennecartia, Kibaropsis, and Matthaea (all Monimiaceae) contained two or three sets of four distinct chromosomes in 38 somatic chromosomes, suggesting that 2n = 38 was derived by aneuploid reduction from 2n = 40, a tetraploid of x = 10. In light of the overall framework of phylogenetic relationships in the Laurales, we show that x = 11 is an archaic base number in the order and is retained in the Calycanthaceae, which are sister to the remainder of the order. Polyploidization appears to have occurred from x = 11 to x = 22 in a common clade of the Siparunaceae, Atherospermataceae, and Gomortegaceae (although 2n = 42 in the Gomortegaceae), and aneuploid reduction from x = 11 to x = 10 occurred in a common clade of the Hernandiaceae, Lauraceae, and Monimiaceae. To understand chromosome evolution in the Lauraceae, however, more studies are needed of genera and species of Cryptocaryeae.     

Karyotype analysis of medicinal plant <Emphasis Type="Italic">Liriope spicata</Emphasis> var. <Emphasis Type="Italic">prolifera</Emphasis> (Liliaceae)

Karyotype of Liriope spicata var. prolifera, a Chinese endemic species, was described in detail for the first time. Its proto-variety L. spicata was also investigated for comparison. The basic chromosome number of these two species was x = 18. L. spicata var. prolifera, recorded as triploid 2n = 54, consisted of 30 metacentric chromosomes and 24 submetacentric chromosomes. Only one chromosome of the 11th group had a secondary constriction with a satellite in the short arm. L. Spicata was tetraploid 2n = 72 and consisted of four sets of 6 submetacentric chromosomes and 12 metacentric chromosomes without visible satellites. This paper provides further available data on Liriope chromosomes, and also indicates that L. spicata var. prolifera and L. spicata are probably separate species.     

Chromosomes tell half of the story: the correlation between karyotype rearrangements and genetic diversity in sedges,a group with holocentric chromosomes

Chromosome rearrangements may affect the rate and patterns of gene flow within species, through reduced fitness of structural heterozygotes or by reducing recombination rates in rearranged areas of the genome. While the effects of chromosome rearrangements on gene flow have been studied in a wide range of organisms with monocentric chromosomes, the effects of rearrangements in holocentric chromosomes—chromosomes in which centromeric activity is distributed along the length of the chromosome—have not. We collected chromosome number and molecular genetic data in Carex scoparia, an eastern North American plant species with holocentric chromosomes and highly variable karyotype (2n = 56–70). There are no deep genetic breaks within C. scoparia that would suggest cryptic species differentiation. However, genetic distance between individuals is positively correlated with chromosome number difference and geographic distance. A positive correlation is also found between chromosome number and genetic distance in the western North American C. pachystachya (2n = 74–81). These findings suggest that geographic distance and the number of karyotype rearrangements separating populations affect the rate of gene flow between those populations. This is the first study to quantify the effects of holocentric chromosome rearrangements on the partitioning of intraspecific genetic variance.     

两种羽叶菊属植物(菊科:千里光族)的细胞学研究及其系统学意义

该研究首次报道了滇羽叶菊和台湾刘寄奴的染色体数据。结果表明:两者的染色体数量都为48,核型公式均为2n=2x=36m+10sm+2st,与前人报道的刻裂羽叶菊的核型稍有不同。两者的染色体形态均由大到小逐渐变化,核型二型性不明显,但前者染色体明显比后者大。这说明羽叶菊属染色体基数确实应为x=24,且染色体大小在种间有较大差异。细胞学证据表明,该属与蒲儿根属中染色体基数为x=24的类群以及狗舌草属确实近缘。     

Karyomorphology ofCrossostylis (Rhizophoraceae)

We present the first report on somatic chromosome numbers and morphology in eight of 13 recorded species ofCrossostylis, one of inland genera of Rhizophoraceae. The chromosome number ofCrossostylis is 2n=28 in all species examined; therefore, the genus hasx=14, a number which is the smallest and unknown elsewhere in the family. Based onCrossostylis raiateensis, we further present that 24 of 28 chromosomes at metaphase have centromeres at median position, and the remaining four at submedian or subterminal position. The chromosome morphology seems to imply thatCrossostylis might be a tetraploid with the original base numberx=7, but an extensive study in the other inland genera is needed to find such a small chromosome number.     

Chromosome number and secondary chromosomal associations in wild populations of Geranium pratense L. from the cold deserts of Lahaul-Spiti (India)

In this work we studied the meiotic chromosome number and details of secondary chromosomal associations recorded for the first time in Geranium pratense L. from the alpine environments in the cold deserts of Lahaul-Spiti (India). All the presently studied individuals of the species existed at 4x level (x = 14). The present chromosome count of n = 28 in the species adds a new cytotype to the already existing diploid chromosome count of 2n = 28 from the Eastern Himalayas and outside of India. Out of the six accessions scored presently four showed normal meiotic course. However, two accessions investigated from Mud, 3800 m and Koksar, 3140 m depicted abnormal meiotic course due to the presence of multivalents and univalents, and secondary associations of bivalents/chromosomes. The secondary chromosomal associations in the species existed among bivalents/chromosomes were noticed in the PMCs at prophase-I (diakinesis) and persisted till the separation of sister chromatids at M-II. The variation in the number of bivalents/chromosomes involved in the secondary associations at M-I (2–8) and A-I/M-II (2–12) has also been recorded. The occurrence of such secondary associations of bivalents/chromosomes in G. pratense which existed at 4x level indicated the secondary polyploid nature of the species.     

Cytology and systematics in JapaneseArisaema (Araceae)

Chromosome numbers are determined from 37 populations attributed to 22 taxa of JapaneseArisaema. Of them, chromosome numbers ofA. limbatum var.conspicuum (2n=26),A. minus (2n=26),A. nambae (2n=28) andA. seppikoense (2n=26) are determined for the first time. New chromosome numbers, 2n=26, are reported forA. aequinoctiale, A. limbatum, A. stenophyllum, A. undulatifolium andA. yoshinagae. Three modes of basic chromosome numbers,x=14,x=13 andx=12, occur in JapaneseArisaema. Precise karyotypic comparisons of 20 taxa reveal that taxa withx=14 andx=13 share 26 major chromosome arms and have an obvious chromosomal relationship. One of two submeta-centric chromosomes inx=13 corresponds to two telo-centric chromosomes inx=14. InA. ternatipartitum with 2n=6x=72, ten out of 12 basic chromosomes are the most similar in size and arm ratio with larger ten chromosomes ofA. ringens among JapaneseArisaema examined. A basic chromosome number ofx=14 is the commonest in the genusArisaema and the remaining basic chromosome numbers,x=13 andx=12, seem to be derived through dysploidal reduction by translocating large segments of major arm of telo-centric chromosome onto other minor arm of telo-centric followed by loss of the remainings including a centromere, and by loss of two telo-centrics fromx=14, respectively. Some systematic problems of JapaneseArisaema are discussed based on new cytological data.Arisaema hatizyoense, A. minus andA. nambae are accepted as independent species.     

Chromosomes of the caryophyllidean tapeworm Glaridacris laruei

The chromosomes of the monozoic tapeworm Glaridacris laruei, from 4 locations in New York State, were studied in leucobasic fuchsin stained squashes of testes and vitelline cells. The diploid chromosome number is 16. Metaphase figures from vitelline cells consist of 3 pairs of metacentrics (“V's”), 4 pairs of acrocentrics (“rods”), and 1 pair of submetacentrics (“J's”). The complement is characterized by a pair of metacentrics 9 μm long, representing 11.5% of the total chromosome length. The shortest are acrocentrics, 2–4 μm long. Meiosis was observed only in spermatogenesis, which proceeds as usual with normal sperm formed after 2 meiotic divisions. Colchicine pretreatment did not facilitate analysis of chromosomes. The scarcity of cell division in 2 populations of G. laruei suggests a possible mitotic rhythm or temperature effect on cell division. Similarities were observed between the the complements of G. laruei and Hunterella nodulosa (2n = 14). A theoretical idiogram, constructed from that of G. laruei, closely resembles H. nodulosa, indicating that there may be a close cytological relationship between these phenotypically different caryophyllids. An idiogram and photographs of chromosomes supplement the paper.     

Sugarcane genome architecture decrypted with chromosome‐specific oligo probes

Sugarcane (Saccharum spp.) is probably the crop with the most complex genome. Modern cultivars (2n = 100–120) are highly polyploids and aneuploids derived from interspecific hybridization between Saccharum officinarum (2n = 80) and Saccharum spontaneum (2n = 40–128). Chromosome‐specific oligonucleotide probes were used in combination with genomic in situ hybridization to analyze the genome architecture of modern cultivars and representatives of their parental species. The results validated a basic chromosome number of x = 10 for S. officinarum. In S. spontaneum, rearrangements occurred from a basic chromosome of x = 10, probably in the Northern part of India, in two steps leading to x = 9 and then x = 8. Each step involved three chromosomes that were rearranged into two. Further polyploidization led to the wide geographical extension of clones with x = 8. We showed that the S. spontaneum contribution to modern cultivars originated from cytotypes with x = 8 and varied in proportion between cultivars (13–20%). Modern cultivars had mainly 12 copies for each of the first four basic chromosomes, and a more variable number for those basic chromosomes whose structure differs between the two parental species. One?four of these copies corresponded to entire S. spontaneum chromosomes or interspecific recombinant chromosomes. In addition, a few inter‐chromosome translocations were revealed. The new information and cytogenetic tools described in this study substantially improve our understanding of the extreme level of complexity of modern sugarcane cultivar genomes.     

Cytological investigations on two species of allocreadiid trematodes with special reference to the occurrence of triploidy and parthenogenesis in Allocreadium fasciatusi

Karyotypes and cytological details of gametogenesis were analysed for Allocreadium handiai and A. fasciatusi. Mitotic plates studied in squashes of testes, ovary, eggs and intramolluscan stages showed that A. handiai is a diploid (2n = 14) with six pairs of submetacentrics and one pair of subtelocentrics. Total chromosome length of the diploid complement was 86.57 μm, the largest chromosome measured 8.87 μm (10.24% total chromosome length [TCL]) and the smallest was 2.83 μm (3.28% TCL). Squashes of testes revealed the presence of all stages of spermatogenesis with spermatocytes in various stages of meiotic activity and spermatids containing bundles of spermatozoa. Stages of development of the ovum conclusively proved that reproduction takes place by amphimixis. Mitotic figures of A. fasciatusi, on the other hand, revealed that it is a triploid (3n = 21) with three metacentrics, 12 submetacentrics and six subtelocentrics. The mean total chromosome length of the triploid complement was 137.54 μm. The largest chromosome measured 10.37 μm (7.54% TCL) and the smallest measured 2.67 μm (1.94% TCL). Spermatogenesis was abortive with no evidence of synaptic pairing and spermatozoa were not produced. Eggs remained unfertilized and reproduction was achieved by parthenogenesis which is of mitotic type. The karyotypes of the two species differed not only in the ploidy level but also in the centromeric indexes of certain chromosomes.