Cytological Study of Cypripedium japonicum Thunb. (Orchidaceae Juss.): An Endangered Species from Korea

Changes in chromosome number and karyotype evolution are important to plant diversification, as they are both major drivers of speciation processes. Herein, chromosome number, karyotype, and genome size of the Korean lady’s slipper orchid Cypripedium japonicum Thunb., an endangered species, were investigated in natural populations. Furthermore, all cytological data from this species are reported herein for the first time. The chromosome number of all investigated C. japonicum plants was diploid (2n = 2x = 22), with x = 11 as base chromosome number, whereby the species can now be clearly distinguished from the Japanese lady’s slipper orchid. The karyotypes of all studied individuals were of similar length, symmetrical, and rather unimodal. Flow cytometry of the C. japonicum revealed that the genome size ranged from 28.38 to 30.14 pg/1C. Data on chromosome number and karyotypes were largely consistent with previous results indicating that Korean (x = 11) populations of C. japonicum are more closely related to Chinese populations (x = 11) compared to Japanese (x = 10) populations. These comprehensive cytological results will benefit the efforts to discriminate the geographically isolated and endangered Eastern Asian (China, Japan, and Korea) lady’s slipper orchid species.

Karyotype analysis of Aeluropus species (Poaceae)

Aeluropus, a member of Poaceae subfam. Chloridoideae, includes six species, three of which occur in Iran. They are perennial halophytes of deserts and coastal marshlands of Iran. The genus is considered as a rich genetic source for gene manipulation and using it for crop improvement. Previous studies showed that members of Chloridoideae have small chromosomes and the base chromosome number n = 10. There are few chromosome records for Aeluropus species. Somatic metaphases of seven populations of three Aeluropus species were studied. The first chromosome counts (2n = 20) based on Iranian material for three species, A. macrostachyus, A. littoralis and A. lagopoides, are concordant with previous records outside Iran; mitotic number for A. macrostachyus is recorded here for the first time.

The Mitragyna speciosa (Kratom) Genome: a resource for data-mining potent pharmaceuticals that impact human health

Mitragyna speciosa (kratom) produces numerous compounds with pharmaceutical properties including the production of bioactive monoterpene indole and oxindole alkaloids. Using a linked-read approach, a 1,122,519,462 bp draft assembly of M. speciosa “Rifat” was generated with an N50 scaffold size of 1,020,971 bp and an N50 contig size of 70,448 bp that encodes 55,746 genes. Chromosome counting revealed that “Rifat” is a tetraploid with a base chromosome number of 11, which was further corroborated by orthology and syntenic analysis of the genome. Analysis of genes and clusters involved in specialized metabolism revealed genes putatively involved in alkaloid biosynthesis. Access to the genome of M. speciosa will facilitate an improved understanding of alkaloid biosynthesis and accelerate the production of bioactive alkaloids in heterologous hosts.

Cytogenetics, Ploidy, and Genome Sizes of Camellia and Related Genera

Camellia L., the most speciose member of the diverse tea family Theaceae, has a long and complex horticultural history. Extensive cultivation and hybridization have produced thousands of varieties of Camellia, including commercially important crops such as cultivated tea, oilseed, and iconic flowering shrubs. Cytogenetics of Camellia and related genera is complicated; chromosome number and ploidy can vary widely between species, and interspecific and interploid hybridization occurs. However, specific information regarding cytogenetics of many species, cultivars, and modern hybrids is lacking. The objectives of this study were to compile a consolidated literature review of the cytogenetics of Camellia and related genera and to determine chromosome numbers, ploidy, and genome sizes of specific accessions of selected species, cultivars, and interspecific and interploid hybrids. A review of the existing literature regarding Theaceae cytogenetics is presented as a consolidated reference comprising 362 taxa. Genome sizes were determined with flow cytometry using propidium iodide as a fluorochrome and Pisum sativum ‘Ctirad' and Magnolia virginiana ‘Jim Wilson’ as internal standards. Chromosome numbers of selected taxa were determined using traditional cytology and were used to calibrate genome sizes with ploidy level. Our results confirmed a base chromosome number of x = 15 for Theeae including Camellia, x = 17 for Stewartiae, and x = 18 for Gordoniae. Surveyed camellias ranged from 2n = 2x = 30 to 2n = 8x = 120, including diploids, triploids, tetraploids, pentaploids, hexaploids, and octoploids. Previously uncharacterized taxa such as Camellia azalea, C. amplexicaulis, C. chrysanthoides, C. cordifolia, C. cucphuongensis, C. flava, C. nanyongensis, and C. trichoclada were found to be diploid. Ploidy was also newly determined for Schima argentea, S. khasiana, S. remotiserrata, and S. sinensis (all diploids). Both diploid and triploid Stewartia ovata were found, and a ploidy series was discovered for Polyspora that ranged from diploid to octoploid. Ploidy determinations were used to confirm or challenge the validity of putative interploid hybrids. Monoploid genome sizes varied among subfamily and genera, with 1Cx values ranging from 0.80 pg for Franklinia to a mean of 3.13 pg for Camellia, demonstrating differential rates of genome expansion independent of ploidy. Within Camellia, monoploid genome sizes varied among subgenera, sections, and some species (range, 2.70–3.55 pg). This study provides a consolidated and expanded knowledgebase of ploidy, genome sizes, hybridity, and reproductive pathways for specific accessions of Camellia and related genera that will enhance opportunities and strategies for future breeding and improvement within Theaceae.

Anemonastrum tenuicaule and A. antucense (Ranunculaceae), new combinations for a New Zealand endemic species and its South American relative

A rational taxonomic circumscription of genera in tribe Anemoneae (Ranunculaceae) is briefly discussed. It is concluded that, in view of the morphological diversity of the group and recent molecular phylogenetic findings, a moderately narrow approach to the re-circumscription of genera earlier included in Anemone sensu lato is preferable, in particular, with the recognition of the lineage with the base chromosome number x = 7 (Anemonesubgen.Anemonidium) as two genera, Hepatica sensu stricto and Anemonastrum in an expanded circumscription (including Anemonidium, Arsenjevia, Jurtsevia, and Tamuria). Following these conclusions, new nomenclatural combinations are proposed for two related species endemic to New Zealand and South America, respectively: Anemonastrumtenuicaule (= Anemonetenuicaulis, Ranunculustenuicaulis) and Anemonastrumantucense (= Anemoneantucensis). Information on typification is updated: the lectotype of Anemoneantucensis is the specimen from P and not a specimen from G, and the lectotype of Ranunculustenuicaulis is a specimen from AK. Biogeographic scenarios already proposed to explain the relationship of these two species and some other South America – New Zealand distribution patterns are discussed. It is concluded that the long-distance dispersal scenario fits best the available data for Anemonastrum. Two host-specific and geographically restricted species of Urosystis parasitizing A.tenuicaule and A.antucense are briefly discussed.

Classification of the Relhania generic group (Asteraceae, Gnaphalieae) revisited using molecular phylogenetic analysis

Phylogenetic relationships within the Relhania generic group, a southern African lineage of 45 yellow-flowered daisy species, are examined using parsimony and Bayesian analysis of plastid DNA, nuclear DNA, and morphological characters. The resulting phylogenetic hypothesis indicates that the species fall into two clades, one comprising the genera containing short-lived (annual / biennial) species, and the other exclusively perennial. Within the perennial clade, containing six genera, several well-supported and morphologically coherent clades are recovered. However, there is substantial generic non-monophyly and many relationships lack resolution, with several species being unplaced. Subdivision into multiple genera would require the recognition of up to twelve small or monospecific genera, and lack of resolution would render this solution potentially unstable. Instead, the six currently-recognised perennial genera Antithrixia, Comborhiza, Oreoleysera, Relhania and Rosenia are here synonymized under the oldest name, Oedera Linnaeus. An infrageneric taxonomy comprising eight sections is proposed for Oedera sensu amplo. This new, enlarged concept of Oedera is defined by the perennial life-history, by leaves with involute or flat margins, by pappus bristles (if present) that are never plumose, and by a base chromosome number of x = 7. Keys to the genera, an updated description of Oedera sensu amplo, and keys to the sections and species are provided. A total of 25 new combinations is made.

Estudios cromosómicos en Lycium (Solanaceae) de Norteamérica

The results of chromosomal studies reported for species of Lycium of the world are presented. Meiotic chromosome numbers were determined from pollen mother-cell squashes of North American taxa of Lycium. In a single case, a mitotic chromosome number was determined from the radicle of a germinating seed. The taxa studied were: L. andersonii Gray var. andersonii, L. andersonii var. deserticola (C. L. Hitchc.) Jepson, L. andersonii var. pubescens S. Wats., L. andersonii var. wrightii A. Gray, L. berlandieri Dun. var. berlandieri, L. berlandieri var. parviflorum (Gray) Terrac., L. berlandieri var. peninsulare ( Brandeg.) C. L. Hitchc., L. brevipes Benth. var. brevipes, L. californicum Nutt. ex Gray var. californicum, L. californicum var. Arizonicum A. Gray, L. cal.ifornicum var. interior Chiang, L. carolinianum var. Quadrifidum ( Moc. & Sessé ex Dun. ) C. L. Hitchc., L. cooperi A. Gray, L. macrodon A. Gray var. macrodon, L. nodosum var. isthmense ( Chiang) Chiang, L. pallidum Miers var. pallidum, L. parishii A. Gray var. parishii, L. parishii var. modest1tm ( I. M. Johnst.) Chiang, L. puberulum var. berberidoides ( Correll) Chiang, and L. torreyi A. Gray. Chromosome numbers of n = 12, 24, 48, 60, and 2n = 24 were found. It is concluded rhat x = 12 is the base chromosome number for Lycium. The origin of n = 18, previously reported, is discussed.

Phylogenetic position and independent generic status of Indocypraea (Asteraceae-Heliantheae-Ecliptinae): evidence from chloroplast DNA sequences

Indocypraea (Asteraceae-Heliantheae-Ecliptinae) is a newly-erected monotypic genus, containing only I. montana. Historically, this species has been variously included in Verbesina, Wedelia, and Wollastonia, and its position has never been investigated from a molecular phylogenetic perspective. Based on chloroplast DNA sequences, I revealed that I. montana is only remotely related to these genera, and is sister to Synedrella with strong support. This topology is also significantly favored by the statistical topology tests. The generic status of Indocypraea is further supported by the achenes brownish yellow and densely dotted with white or yellowish white mottles, and a base chromosome number of x = 37, both of which are distinct in the subtribe Ecliptinae. Additionally, I clarify the identity of Wedelia wallichii var. megalantha, and synonymize it with I. montana.

A study of chromosome and gametophyte development in Pellaea connectens C. Chr.

Pellaea connectens C. Chr., a cheilanthoid fern species, is rare and endemic to West Sichuan, China, and has an ambiguous taxonomical status. Recent molecular phylogenetic work has supported that it is a member of the genus Argyrochosma. In this research, we studied chromosome number and gametophyte development of this species to further elucidate its phylogenetic placement. We found that Pellaea connectens is a sexual tetraploid species with 64 spores per sporangium and with a base chromosome number of x = 27, which is consistent with Argyrochosma and different from other cheilanthoid ferns. We also found that the spore germination pattern of Pellaea connectens is of the Vittaria type and subsequent gametophyte development process is of the Ceratopteris type. All of the above concur with the characteristics of Argyrochosma nivea. Most of the gametophytes of Pellaea connectens reach an adult stage with a cordate symmetric shape, with a few developed as irregularly lobed prothalli. We conclude that cytology and gametophyte development characters support the previous taxonomic treatment of removing Pellaea connectens from Pellaea to Argyrochosma.