Arabis Species Research Articles

Seed germination ecophysiology and conservation of three endemic Arabis species (Brassicaceae) of Cyprus

Seed germination ecophysiology and conservation of three endemic Arabis species (Brassicaceae) of Cyprus

Complete chloroplast genome of two Arabis L. species from Korea and assessment of their phylogenetic relationship in plastome based phylogeny

Arabis stelleri DC. and A. takesimana Nakai belong to the family Brassicaceae. Arabis stelleri is widely distributed in East Asia, and A. takesimana is a Korean endemic plant. In this study, we report the complete chloroplast genomes of both species, measuring 153,577 bp for A. stelleri and 153,557 bp for A. takesimana. The plastome of A. stelleri comprises two inverted repeats (IRs) of 26,421 bp, a large single-copy (LSC) region measuring 82,705 bp, and a small single-copy (SSC) region of 18,030 bp. Whereas A. takesimana has IR regions of 26,426 bp, an LSC of 82,694 bp, and an SSC of 18,011 bp. Both the plastomes contain 131 total genes, 86 protein-coding genes, 37 tRNA genes, 8 rRNA genes, and 36.4% GC content. The organization and gene content of both plastomes were found to be similar to previously reported Arabis plastomes. In addition, we have tested the phylogenetic position of both the Arabis species and the relationship of the genus Arabis with other Brassicaceae members in comprehensive family-level plastome-based phylogeny. Arabis stelleri and A. takesimana are phylogenetically placed within the Arabis clade and show a close relationship to A. flagellosa, A. nipponica, A. paniculata, and A. hirsuta.

The new tribe Fourraeeae (Brassicaceae) and two Moroccan Arabis species transferred to the new genus Hurkaea

The taxonomic limits of two Moroccan Arabis species are revised based on a critical evaluation of morphology in light of phylogenetic and cytogenetic studies that also included the monospecific European Fourraea. As a result, the new tribe Fourraeeae, the new genus Hurkaea and new combinations H. josiae, H. conringioides, and H. conringioides subsp. humbertii are proposed. Keys to distinguish genera, species and subspecies are provided.

Transposition and duplication of MADS-domain transcription factor genes in annual and perennial Arabis species modulates flowering

The timing of reproduction is an adaptive trait in many organisms. In plants, the timing, duration, and intensity of flowering differ between annual and perennial species. To identify interspecies variation in these traits, we studied introgression lines derived from hybridization of annual and perennial species, Arabis montbretiana and Arabis alpina, respectively. Recombination mapping identified two tandem A. montbretiana genes encoding MADS-domain transcription factors that confer extreme late flowering on A. alpina These genes are related to the MADS AFFECTING FLOWERING (MAF) cluster of floral repressors of other Brassicaceae species and were named A. montbretiana (Am) MAF-RELATED (MAR) genes. AmMAR1 but not AmMAR2 prevented floral induction at the shoot apex of A. alpina, strongly enhancing the effect of the MAF cluster, and MAR1 is absent from the genomes of all A. alpina accessions analyzed. Exposure of plants to cold (vernalization) represses AmMAR1 transcription and overcomes its inhibition of flowering. Assembly of the tandem arrays of MAR and MAF genes of six A. alpina accessions and three related species using PacBio long-sequence reads demonstrated that the MARs arose within the Arabis genus by interchromosomal transposition of a MAF1-like gene followed by tandem duplication. Time-resolved comparative RNA-sequencing (RNA-seq) suggested that AmMAR1 may be retained in A. montbretiana to enhance the effect of the AmMAF cluster and extend the duration of vernalization required for flowering. Our results demonstrate that MAF genes transposed independently in different Brassicaceae lineages and suggest that they were retained to modulate adaptive flowering responses that differ even among closely related species.

Exploring the History of Chloroplast Capture in Arabis Using Whole Chloroplast Genome Sequencing.

Chloroplast capture occurs when the chloroplast of one plant species is introgressed into another plant species. The phylogenies of nuclear and chloroplast markers from East Asian Arabis species are incongruent, which indicates hybrid origin and shows chloroplast capture. In the present study, the complete chloroplast genomes of A. hirsuta, A. nipponica, and A. flagellosa were sequenced in order to analyze their divergence and their relationships. The chloroplast genomes of A. nipponica and A. flagellosa were similar, which indicates chloroplast replacement. If hybridization causing chloroplast capture occurred once, divergence between recipient species would be lower than between donor species. However, the chloroplast genomes of species with possible hybrid origins, A. nipponica and A. stelleri, differ at similar levels to possible maternal donor species A. flagellosa, which suggests that multiple hybridization events have occurred in their respective histories. The mitochondrial genomes exhibited similar patterns, while A. nipponica and A. flagellosa were more similar to each other than to A. hirsuta. This suggests that the two organellar genomes were co-transferred during the hybridization history of the East Asian Arabis species.

East Asian Arabis species (Brassicaceae) exemplify past hybridization and subsequent emergence of three main evolutionary lineages in East Asia, America and the amphi-Beringian region

East Asian Arabis species (Brassicaceae) exemplify past hybridization and subsequent emergence of three main evolutionary lineages in East Asia, America and the amphi-Beringian region

Divergence of annual and perennial species in the Brassicaceae and the contribution of cis-acting variation at FLC orthologues.

Variation in life history contributes to reproductive success in different environments. Divergence of annual and perennial angiosperm species is an extreme example that has occurred frequently. Perennials survive for several years and restrict the duration of reproduction by cycling between vegetative growth and flowering, whereas annuals live for 1 year and flower once. We used the tribe Arabideae (Brassicaceae) to study the divergence of seasonal flowering behaviour among annual and perennial species. In perennial Brassicaceae, orthologues of FLOWERING LOCUS C (FLC), a floral inhibitor in Arabidopsis thaliana, are repressed by winter cold and reactivated in spring conferring seasonal flowering patterns, whereas in annuals, they are stably repressed by cold. We isolated FLC orthologues from three annual and two perennial Arabis species and found that the duplicated structure of the A. alpina locus is not required for perenniality. The expression patterns of the genes differed between annuals and perennials, as observed among Arabidopsis species, suggesting a broad relevance of these patterns within the Brassicaceae. Also analysis of plants derived from an interspecies cross of A. alpina and annual A. montbretiana demonstrated that cis‐regulatory changes in FLC orthologues contribute to their different transcriptional patterns. Sequence comparisons of FLC orthologues from annuals and perennials in the tribes Arabideae and Camelineae identified two regulatory regions in the first intron whose sequence variation correlates with divergence of the annual and perennial expression patterns. Thus, we propose that related cis‐acting changes in FLC orthologues occur independently in different tribes of the Brassicaceae during life history evolution.

Essential Oil Composition of Endemic Arabis purpurea Sm. & Arabis cypria Holmboe (Brassicaceae) from Cyprus.

There are very few reports on the phytochemistry of the Arabis L. (Brassicaceae) species in the literature. Here we present essential oil composition of aerial parts of two endemic Arabis species from Cyprus. The essential oils of Arabis purpurea Sm. and Arabis cypria Holmboe afforded very low oil yields (< 0.01% (v/w) yield). Sixty six compounds were identified in the essential oil of A. purpurea that represent 82.75 ± 0.21 % (n = 3) of the oil. The major components of the oil were nonacosane 16.18 ± 0.13 %, heptacosane 14.91 ± 0.17 %, hexahydrofarnesyl acetone 12.44 ± 0.10 % and phytol 7.36 ± 0.10 % (n = 3). Forty three compounds were identified in the essential oil of A. cypria which represent 81.28 ± 1.55 % (n = 3) of the oil. The major components of the oil were nonacosane 20.25 ± 0.47 %, heptacosane 9.13 ± 1.88 %, hexahydrofarnesyl acetone 9.03 ± 0.44 % and 1-tetradecanol 4.38 ± 2.60 % (n = 3). To the best of our knowledge this is the first report on the essential oil compositions of these species.

Arabis watsonii (P.H.Davis) F.K.Mey.: An overlooked cruciferous species from eastern Anatolia and its phylogenetic position.

Arabis watsonii (P.H.Davis) F.K.Mey. was initially reported as Thlaspi watsonii P.H.Davis in Flora of Turkey. Although F.K.Meyer transferred this species to Arabis L., this species has been overlooked and treated as Thlaspi L. in relevant literature for Flora of Turkey. In this study this species was evaluated using molecular (nuclear ITS and plastidic trnL-F sequences) and morphological data. Results clearly show that Arabis watsonii is sister to the Arabis hirsuta aggregate and its relatives. In conclusion, our results increased the number of known Arabis species in Turkey to 23. Furthermore, detailed description and distribution of the species are given and a new IUCN threat category for Arabis watsonii is proposed.

Arabis erecta (Brassicaceae), a new species from Republic of Korea

A new species of Arabis L. (Brassicaceae), A. erecta Y.Y. Kim &amp; C.G. Jang, was discovered in Gyeongsangbuk-do Province, Republic of Korea and is described and illustrated here. The species is similar to A. stelleri DC. and A. takesimana Nakai in its general vegetative and floral morphology. However, the new species is distinguished by its glabrous leaves surface, not inflated receptacle, and fruiting pedicels and siliques appressed to the rachis. In addition, the diagnostic characters between related species, an identification key, and a distribution map are provided.

A Time-Calibrated Road Map of Brassicaceae Species Radiation and Evolutionary History.

The Brassicaceae include several major crop plants and numerous important model species in comparative evolutionary research such as Arabidopsis, Brassica, Boechera, Thellungiella, and Arabis species. As any evolutionary hypothesis needs to be placed in a temporal context, reliably dated major splits within the evolution of Brassicaceae are essential. We present a comprehensive time-calibrated framework with important divergence time estimates based on whole-chloroplast sequence data for 29 Brassicaceae species. Diversification of the Brassicaceae crown group started at the Eocene-to-Oligocene transition. Subsequent major evolutionary splits are dated to ∼20 million years ago, coinciding with the Oligocene-to-Miocene transition, with increasing drought and aridity and transient glaciation events. The age of the Arabidopsis thaliana crown group is 6 million years ago, at the Miocene and Pliocene border. The overall species richness of the family is well explained by high levels of neopolyploidy (43% in total), but this trend is neither directly associated with an increase in genome size nor is there a general lineage-specific constraint. Our results highlight polyploidization as an important source for generating new evolutionary lineages adapted to changing environments. We conclude that species radiation, paralleled by high levels of neopolyploidization, follows genome size decrease, stabilization, and genetic diploidization.

Systematics and evolution of arctic‐alpine Arabis alpina (Brassicaceae) and its closest relatives in the eastern Mediterranean

The high mountains in southern Anatolia and the eastern Mediterranean are assumed to play a major role as a primary center of genetic diversity and species richness in Eurasia. We tested this hypothesis by focusing on the widespread perennial arctic-alpine Arabis alpina and its sympatrically distributed closest relatives in the eastern Mediterranean. Plastid (trnL intron, trnL-F intergenic spacer) and nuclear (ITS) DNA sequence analysis was used for phylogenetic reconstruction. Broad-scale plastid haplotype analyses were conducted to infer ancestral biogeographic patterns. Five Arabis species, identified from the eastern Mediterranean (Turkey mainland and Cyprus), evolved directly and independently from A. alpina, leaving Arabis alpina as a paraphyletic taxon. These species are not affected by hybridization or introgression, and species divergence took place at the diploid level during the Pleistocene. Pleistocene climate fluctuations produced local altitudinal range-shifts among mountain glacial survival areas, resulting not only in the accumulation of intraspecific genotype diversity but also in the formation of five local species. We also show that the closest sister group of Arabis alpina consists exclusively of annuals/winter annuals and diverged prior to Pleistocene climatic fluctuations during the colonization of the lowland Mediterranean landscape. These findings highlight that Anatolia is not only a center of species richness but also a center for life-history diversification.

Distribution and Host Range of a Powdery Mildew Fungus Infecting Garlic Mustard, Alliaria petiolata, in Southwestern Ohio

Abstract Garlic mustard is an invasive Eurasian biennial that has rapidly spread throughout the United States. In Southwestern Ohio, many garlic mustard populations are infected with Erysiphe cruciferarum, a causal agent of powdery mildew disease in Brassicaceous plants. We examined the regional distribution of E. cruciferarum on garlic mustard and determined the potential host range of E. cruciferarum on several native Brassicaceous species and selected Brassicaceous crop varieties. A survey of 19 natural areas in western Ohio revealed that populations of garlic mustard with high incidences of powdery mildew were largely centered in Montgomery and Greene Counties in Ohio, with disease incidence decreasing away from Dayton, Ohio. Sampling locations that were on level or southeast facing slopes had significantly higher disease incidences than those on northwest or southwest facing slopes. Five native spring ephemeral species, including four Cardamine species and one Arabis species, showed no obvious signs ...

Colonizing the American continent: Systematics of the genus Arabis in North America (Brassicaceae)

The circumscription of the genus Arabis underwent many and drastic changes within the past. Using DNA sequence information from the nuclear ribosomal RNA and parts of the plastid genome (trnL-trnLF), as well as a critical evaluation of herbarium material from East Asia and North America, we circumscribe the various Arabis taxa of North America. The American and East Asian Arabis species are closely related and, contrary to what was previously believed, they are not closely related to the Eurasian A. hirsuta. Using cpDNA, we found five North American lineages of Arabis with distinct distribution patterns, of which only the purple/red-flowered lineage consists of proven diploids that evolved directly from East Asian progenitors. All other four lineages evolved via ancient hybridization either on the Asian continent prior to migration to North America or showed significant evidence for hybridization and reticulation while diversifying on the American continent. We also provide the first evidence for the systematic circumscription of East Asian Arabis taxa, which together with the North American taxa, form one clade distantly related to European A. ciliata and Eurasian A. hirsuta. The findings also represent the first record of A. pycnocarpa for the floras of China, Japan, and Russian Far East.

Complex metabolism of aromatic glucosinolates in Pieris rapae caterpillars involving nitrile formation, hydroxylation, demethylation, sulfation, and host plant dependent carboxylic acid formation

We investigated the metabolism of two chain elongated phenolic glucosinolates and the corresponding O-methyl derivatives upon ingestion by caterpillars of the butterfly Pieris rapae (L.). The glucosinolates (GSLs) were 4-hydroxyphenethylGSL, ( R)-2-hydroxy-2-(4-hydroxyphenyl)ethylGSL, 4-methoxyphenethylGSL, and ( R)-2-hydroxy-2-(4-methoxyphenyl)ethylGSL, variously occurring in foliage of two Arabis species: Arabis hirsuta (L.) Scop. and Arabis soyeri Reut. & Huet subsp. subcoriacea (Gren. ex Nyman) Breitstr. (Brassicaceae). Frass from caterpillars reared on each Arabis species contained two sulfated nitriles (4-sulfates of 3-(4-hydroxyphenyl)propanenitrile and 3-hydroxy-3-(4-hydroxyphenyl)propanenitrile) as apparent GSL metabolites. Comparison of glucosinolate levels in foliage and levels of sulfated nitriles in frass, and experiments with isolated GSLs spiked to crucifer foliage and ingested by P. rapae, demonstrated that phenolic GSLs and the corresponding O-methyl derivatives were metabolised to sulfated nitriles, and that metabolites lacking a β-hydroxy group were partially hydroxylated in this position during metabolism in P. rapae. In contrast, an induction experiment did not show increased levels of β-hydroxylated GSLs in A. soyeri plants upon caterpillar feeding. Frass contents of other putative GSL metabolites from the interaction with the two Arabis species differed significantly; caterpillars reared on A. hirsuta excreted significant amounts of four carboxylic acids (3-(4-hydroxyphenyl)propanoic acid, 3-hydroxy-3-(4-hydroxyphenyl)propanoic acid, and the corresponding 4-sulfates), which were low or absent when the caterpillars were reared on A. soyeri. The excreted carboxylic acids could be formed by hydrolysis of nitriles to carboxylic acids in caterpillar guts by an ingested nitrilase enzyme from A. hirsuta foliage; this hypothesis was supported by demonstration of 3-(4-hydroxyphenyl)propanenitrile hydrolysing nitrilase activity (E.C. 3.5.5.x) in a crude A. hirsuta extract. Some hypothetic metabolites, glycine conjugates of phenolic carboxylic acids, were not detected. Conditions for group separation and HPLC isolation of intact GSLs and sulfated metabolites were optimised, NMR spectroscopic data of the compounds are reported, and evolutionary and ecological implications are discussed.

Contribution to ITS phylogeny of the Brassicaceae, with special reference to some Asian taxa

Sequence data from the nuclear ribosomal internal transcribed spacer (ITS) region for 189 accessions representing 184 species in 121 genera of Brassicaceae were used to determine monophyly of tribes and genera, tribal boundaries, and component genera. Parsimony analysis and Bayesian inference suggest that the tribes Camelineae and Arabideae are polyphyletic and should be subdivided into smaller tribes. The study also supports the recent recognition of the new tribes Aphragmeae, Biscutelleae, Buniadeae, Calepineae, Conringieae, Dontostemoneae, Erysimeae, Malcolmieae, Megacarpaeeae, and Turritideae. The data argue for the placement of Borodinia in the tribe Boechereae, Litwinowia and Pseudoclausia in the Chorisporeae, Atelanthera and Streptoloma in the Euclidieae, and Megacarpaea and Pugionium in the Megacarpaeeae, and exclusion of Asperuginoides, Didymophysa, and Ptilotrichum from the Alysseae, Macropodium, Pseudoturritis, and Stevenia from the Arabideae, and Crucihimalaya, Irenepharsus, Pachycladon, and Turritis from the Camelineae. Finally, the findings support the expansion of Stevenia to include both Berteroella and Ptilotrichum, Sterigmostemum to include Oreoloma and one species of Anchonium, Crucihimalaya to include Transberingia and several species of Arabis, and Parrya to include Pseudoclausia. The data also suggest that Calymmatium and Olimarabidopsis may be congeneric.

Arabis Elgonensis (Brassicaceae), a New Species from Mount Elgon, Uganda

ABSTRACT Arabis elgonensis (Brassicaceae), a new species from Mount Elgon, Uganda, is described and illustrated. Its distinguishing characters from the other species of Arabis are discussed.

A new species of Arabis (Brassicaceae) from inner Anatolia

A new species of Arabis L., A. erikii Mutlu sp. nov., is described and illustrated. The species is restricted to inner Anatolia, south-west of Sivas. It grows on steppes. Diagnostic morphological characters are given for discrimination from the most similar taxa. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 145, 251–256.

Phylogenetic Position and Generic Limits of Arabidopsis (Brassicaceae) Based on Sequences of Nuclear Ribosomal DNA

The primary goals of this study were to assess the generic limits and monophyly of Arabidopsis and to investigate its relationships to related taxa in the family Brassicaceae. Sequences of the internal transcribed spacer region (ITS-1 and ITS-2) of nuclear ribosomal DNA, including 5.8S rDNA, were used in maximum parsimony analyses to construct phylogenetic trees. An attempt was made to include all species currently or recently included in Arabidopsis, as well as species suggested to be close relatives. Our findings show that Arabidopsis, as traditionally recognized, is polyphyletic. The genus, as recircumscribed based on our results, (1) now includes species previously placed in Cardaminopsis and Hylandra as well as three species of Arabis and (2) excludes species now placed in Crucihimalaya, Beringia, Olimarabidopsis, Pseudoarabidopsis, and lanhedgea.

A new species of Arabis L. (Brassicaceae) from South Anatolia

Abstract A new species of Arabis L A. alanyensis H. Duman sp. nov., is described and illustrated. The species is restricted to the north of Alanya (Antalya), It grows on calcareous rocks. Diagnostic morphological characters for discrimination from the most similar taxa are given.