Development and characterization of microsatellite markers for Berberis thunbergii (Berberidaceae)

? Premise of the study: Microsatellite markers were isolated and characterized in Berberis thunbergii, an invasive and ornamental shrub in the eastern United States, to assess genetic diversity among populations and potentially identify horticultural cultivars. ? Methods and Results: A total of 12 loci were identified for the species. Eight of the loci were polymorphic and were screened in 24 individuals from two native (Tochigi and Ibaraki prefectures, Japan) and one invasive (Connecticut, USA) population and 21 horticultural cultivars. The number of alleles per locus ranged from three to seven, and observed heterozygosity ranged from 0.048 to 0.636. ? Conclusions: These new markers will provide tools for examining genetic relatedness of B. thunbergii plants in the native and invasive range, including phylogeographic studies and assessment of rapid evolution in the invasive range. These markers may also provide tools for examining hybridization with other related species in the invasive range.     

The Invasion Ecology of Japanese Barberry (Berberis thunbergii) in the New England Landscape

Japanese barberry (Berberis thunbergii) has been characterized as one of the most widely known and planted exotic shrubs in the United States. It was first introduced to the US in the late 1800s. By 1920 the planting of Japanese barberry was encouraged as an ornamental shrub replacing the common barberry (Berberis vulgaris). Japanese barberry began spreading from cultivation in suburban and selected rural retreats by the 1920s, and had dispersed rapidly throughout the northeast by the 1960s. By the 1970s it was recognized as a problematic invasive in the northeast. It is readily dispersed primarily by birds. Fruit production varies with light level, but even under very low light levels (4% full sun) some seeds are produced. Fruits are dispersed in late fall through late winter. Seed dispersal curves are highly leptokurtic; most seedling are found under or adjacent to adults, but a small number may be found tens of meters from the nearest adult. Japanese barberry thrives under a broad range of light and soil moisture conditions. Significant variation in stem growth can be explained as a function of light level. Even at less than 1% full sun, some positive stem growth can occur. Survival is quite high at intermediate to high light levels, and only under the lowest light levels (<1% full sun) does survival drop significantly. Biomass of Japanese barberry in field plots can be largely explained as a function of light availability and soil moisture. The biomass of co-occurring species is suppressed by Japanese barberry, and recovery is slow in the first year following Japanese barberry removal except under high light levels. Glyphosate (Roundup) applied in early spring at first leaf out, when little else is in leaf, provides an effective means of eradicating Japanese barberry populations.     

Effects of Japanese barberry (Ranunculales: Berberidaceae) removal and resulting microclimatic changes on Ixodes scapularis (Acari: Ixodidae) abundances in Connecticut, USA

Japanese barberry (Berberis thunbergii de Candolle) is a thorny, perennial, exotic, invasive shrub that is well established throughout much of the eastern United States. It can form dense thickets that limit native herbaceous and woody regeneration, alter soil structure and function, and harbor increased blacklegged tick (Ixodes scapularis Say) populations. This study examined a potential causal mechanism for the link between Japanese barberry and blacklegged ticks to determine if eliminating Japanese barberry could reduce tick abundance and associated prevalence of Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt, and Brenner). Japanese barberry was controlled at five study areas throughout Connecticut; adult ticks were sampled over three years. Each area had three habitat plots: areas where barberry was controlled, areas where barberry remained intact, and areas where barberry was minimal or absent. Sampled ticks were retained and tested for B. burgdorferi presence. At two study areas, temperature and relative humidity data loggers were deployed in each of the three habitat plots over two growing seasons. Intact barberry stands had 280 ± 51 B. burgdorferi-infected adult ticks/ha, which was significantly higher than for controlled (121 ± 17/ha) and no barberry (30 ± 10/ha) areas. Microclimatic conditions where Japanese barberry was controlled were similar to areas without barberry. Japanese barberry infestations are favorable habitat for ticks, as they provide a buffered microclimate that limits desiccation-induced tick mortality. Control of Japanese barberry reduced the number of ticks infected with B. burgdorferi by nearly 60% by reverting microclimatic conditions to those more typical of native northeastern forests.     

Structure and Dynamics of Populations of Japanese Barberry (Berberis Thunbergii DC.) in Deciduous Forests of New Jersey

Japanese barberry, Berberis thunbergii DC., has become a prominent exotic species in deciduous forests throughout the eastern and midwestern US. Populations range from small plants occurring at low densities to dense, impenetrable thickets of plants with up to 40 stems/individual. A study was undertaken at Morristown National Historical Park in New Jersey to document plant densities, plant size, recruitment through vegetative processes of new shoot initiation and clonal spread and recruitment from seedling establishment, and mortality of stems and plants. Nearly 2000 shoots on 370 plants were individually marked and followed for two growing seasons, and over 1000 seedlings were also individually marked and followed. Populations vary much more in total shoots/area than they do in plant individuals/area, or in mean plant size (shoots/plant), as even the sparse populations have a few large individuals. Shoot mortality is less than new shoot initiation, but most plants do not change in size or change by small numbers of stems. However, the number of new shoots per plant increases as plant size increases. Once plants have three stems, they suffer little or no mortality. Seedling establishment is proportional to the density of shoots, so that as plants grow in size, local recruitment from seed increases. Large numbers of seedlings, and a survival rate of 10%, combine to make seedling recruitment a major component of population increase. The combination of multiple forms of vegetative and seed-based population growth, and the very low rates of plant mortality due to the multi-stemmed growth form explains the ability of this invasive species to rapidly produce dense, persistent populations.     

Elevated native terrestrial snail abundance and diversity in association with an invasive understory shrub,Berberis thunbergii,in a North American deciduous forest

Invasive terrestrial plants often substantially reshape environments, yet how such invasions affect terrestrial snail assemblages remains understudied. We investigated how snail assemblages in deciduous forest soils with dense Berberis thunbergii (Japanese barberry), an invasive shrub in eastern North America, differ from forest areas lacking the shrub. Leaf litter and soil samples were collected from forest patches with dense B. thunbergii understories and adjacent control areas within two exurban forest tracts in western Pennsylvania, U.S.A. Snails were identified to species and quantified by standard diversity metrics. Contrary to our expectations, snails were significantly more abundant and diverse in B. thunbergii-invaded areas. Despite differences in abundance, the snail community composition did not differ between invaded and control habitats. The terrestrial snail assemblage we observed, which was composed entirely of native species, appears to respond favorably to B. thunbergii invasion and therefore may not be negatively impacted by physicochemical changes to soils typically observed in association with the plant. Such findings could reflect the fact that B. thunbergii likely creates more favorable habitat for snails by creating cooler, more humid, and more alkaline soil environments. However, the snail assemblages we retrieved may consist mostly of species with high tolerance to environmental degradation due to a legacy of land use change and acid deposition in the region.     

Germination,growth and survival of <Emphasis Type="Italic">Berberis thunbergii</Emphasis> DC. (Berberidaceae) and <Emphasis Type="Italic">Berberis thunbergii</Emphasis> var. <Emphasis Type="Italic">atropurpurea</Emphasis> in five natural environments

Germination, growth and survival of green Berberis thunbergii and its purple ornamental form, Berberis thunbergii var. atropurpurea, were compared in five natural environments (full sun meadow, edge of woods, moist woods, dry woods, pine woods) to determine whether these two forms have a similar ability to naturalize. Berberis thunbergii and Berberis thunbergii var. atropurpurea had similar germination rates of about 25% at the end of 3 years. Most of the seed germination occurred in year one (89%), with a small amount of additional germination in year two (10%), and even less in year three (1%). Greatest germination occurred in the moist woods and full sun meadow sites and the least occurred at the pine woods site. Germination was reduced in the pine woods environment by the thick leaf litter layer present there. Barberry seedling survival during the first year was only 22% and survival dropped to 11.3% by the end of 2 years. Purple barberry seedlings had a lower 2 year survival rate than green barberry. There was no difference in seedling growth between purple and green barberry seedlings, but surviving seedling growth rates at the five environments were comparable. Seedlings achieved maximum growth in the edge of woods environment, but also grew well in the full sun meadow environment. At harvest, the full sun meadow had the greatest number of seedlings present, while no seedlings survived in the pine woods site.     

春季—冻融交替时期9种落叶及半常绿小灌木抗寒性综合评价

在春季—冻融交替时期,以北京地区迎春、金叶女贞、小花溲疏等9种落叶及半常绿小灌木一年生枝条为试材,通过人工模拟降温,测定其在4~-20℃低温胁迫下的6个生理响应指标,并对各指标进行相关性分析。结果表明,相对电导率、半致死温度、游离-脯氨酸含量和相对含水量这4个生理指标可作为9种小灌木抗寒性的评价指标。利用主成分分析、隶属函数法进行抗寒性综合评价,发现9种小灌木的抗寒性强弱顺序为:小花溲疏紫叶小檗太平花红王子锦带迎春连翘金叶女贞棣棠金山绣线菊。通过聚类分析可将9种小灌木分为3类,小花溲疏和紫叶小檗归为一类,其抗寒性相对较好;太平花、红王子锦带、迎春和连翘聚成一组,抗寒性一般;金叶女贞、棣棠和金山绣线菊聚在一起,抗寒性相对较差。     

The role of land-use history in major invasions by woody plant species in the northeastern North American landscape

Land-use history as a predictor of invasive alien plant distributions has received little study, especially across large spatial and temporal scales. Here we evaluate the importance of land-use history and other environmental characteristics as predictors of the distributions of a suite important invasive woody plant species in the northeastern United States. Using historical aerial photographs, we delineated 69 years (1934–2003) of land-use change across a typically heterogeneous 95 km² landscape. We randomly surveyed over 500 sites for six invasive plant species. We found that land use history patterns strongly affected presence and abundance of the invasive plants as a group, but affected some species more than others. Generally, past agricultural use favored invasive species, whereas intact forest blocks discouraged them. Current land-use trends toward residential/commercial development favor disturbance-adapted species like Celastrus orbiculatus (asiatic bittersweet) and will probably slow the spread of post-agricultural specialists such as Berberis thunbergii (Japanese barberry).     

Japanese barberry seed predation by Rhagoletis meigenii fruit flies harboring Wolbachia endosymbionts

The phytophagous fruit fly Rhagoletis meigenii harbors the bacterium Wolbachia pipientis and, together with Japanese barberry, form a tri-partite symbiosis. R. meigenii is a seed predator of invasive Japanese barberry plants and is dependent on this insect-plant interaction for reproductive success. The endosymbiotic bacterium W. pipientis is a reproductive parasite known to alter the sex ratios of offspring and the fitness of infected host insects. We investigated Japanese barberry fruit for the degree of infestation by R. meigenii and characterized the Wolbachia strain infecting R. meigenii. Densities of R. meigenii in four naturalized stands of Japanese barberry revealed low numbers of fruit flies with high variability in the population densities observed among individual plants. Overall, R. meigenii infested roughly 10–20 % of the Japanese barberry fruits analyzed; fruit with two seeds (vs. one seed) were the most frequently infested. Approximately, 90 % of the R. meigenii tested positive for Wolbachia infection via PCR amplification of the Wolbachia surface protein (wsp) gene. No bacterial strain diversity was observed when comparing multi-locus sequence typing (MLST) profiles within or among five R. meigenii populations in Maine, although the MLST profile obtained from R. meigenii differed from three co-occurring Rhagoletis. The Wolbachia endosymbiont of R. meigenii is a member of the Wolbachia supergroup A and the ST-13 cluster complex.     

Development of microsatellite markers in a riparian shrub, Spiraea thunbergii (Rosaceae)

? Premise of the study: Microsatellite primers in the deciduous shrub Spiraea thunbergii were developed to investigate genetic diversity and population genetic structure. Cross-species transferability was assayed in four congeneric species. ? Methods and Results: Using a compound simple sequence repeat (SSR) marker method, 10 primer sets were identified in Japanese populations of S. thunbergii. The primers amplified compound SSRs with two to five alleles per locus. More than half of the primers were also amplified in S. prunifolia, S. nipponica var. nipponica, and S. japonica. ? Conclusions: These markers might be useful for future studies of population genetics of S. thunbergii and congeneric species.     

Fine-scale geographical structure of genetic diversity in inland wild beet populations

Introgression arising from crop-to-wild gene flow provides novel sources of genetic variation in plant species complexes. Hybridization within the Beta vulgaris species complex is of immediate concern; crop lineages ( B .  vulgaris ssp. vulgaris ) hybridize easily with their wild relatives ( B .  vulgaris ssp. maritima ) thereby threatening wild beet gene diversity with genetic swamping. Hybridization 'hotspots' occur in European seed production areas because inland ruderal wild beets occur and reproduce in sympatry with cultivated beets. We studied gene flow occurring between seed-producing cultivars and ruderal wild B .  vulgaris in southwestern France to determine whether feral beets, arising from unharvested cultivated seed, represent an opportunity for crop-to-wild gene flow. We surveyed 42 inland ruderal beet populations located near seed production fields for nucleo-cytoplasmic variation and used a cytoplasmic marker diagnostic of cultivated lines. Occurrence of cultivated-type cytoplasm within ruderal populations clearly reflected events of crop seed escape. However, we found no genetic signatures of nuclear cultivated gene introgression, which suggests past introgression of cultivated cytoplasm into a wild nuclear background through seed escape rather than recent direct pollen flow. Overall, patterns of genetic structure suggested that inland ruderal wild beet populations act as a metapopulation, with founding events involving a few sib groups, followed by low rates of seed or pollen gene flow after populations are established. Altogether, our results indicate that a long-lived seed bank plays a key role in maintaining cultivated-type cytoplasm in the wild and highlight the need for careful management of seed production areas where wild and cultivated relatives co-occur.     

Introgression between native and prehistorically naturalized (archaeophytic) wild pear (<Emphasis Type="Italic">Pyrus</Emphasis> spp.) populations in Northern Tohoku,Northeast Japan

Hybridization between native and cultivated species is a concern in conservation biology. However, detecting such hybridization and distinguishing true natives from prehistorically naturalized species based on phenotypic characteristics is difficult. Here, we report on introgression between native and prehistorically introduced pear (Pyrus) species in Northern Tohoku (northern end of Honshu Island), Japan. We analyzed 20 microsatellites in 226 wild, seemingly wild, or cultivated materials. Phenetic analysis showed that wild Japanese populations of P. ussuriensis var. ussuriensis in Northern Tohoku, previously considered true natives based on morphology and phytogeography, differed from those in continental Asia, confirming their nativeness. However, Bayesian inference of population structures showed that Japanese P. ussuriensis was genetically admixed with two genetic clusters: true native P. ussuriensis var. ussuriensis and prehistorically introduced P. pyrifolia. Even in the Kitakami Mountains, where true native populations of var. ussuriensis are believed to persist, most wild trees were at least somewhat admixed. Prehistorically introduced then naturalized plants are treated as natives in Japan’s conservation management, and some are considered endangered. However, introgression of prehistorically naturalized P. pyrifolia into threatened native P. ussuriensis var. ussuriensis has occurred. This paper examines the implications for conservation management.     

Plasticity in salt tolerance traits allows for invasion of novel habitat by Japanese knotweed s. l. (Fallopia japonica and F.xbohemica, Polygonaceae)

Japanese knotweeds are among the most invasive organisms in the world. Their recent expansion into salt marsh habitat provides a unique opportunity to investigate how invasives establish in new environments. We used morphology, cytology, and AFLP genotyping to identify taxa and clonal diversity in roadside and salt marsh populations. We conducted a greenhouse study to determine the ability to tolerate salt and whether salt marsh populations are more salt tolerant than roadside populations as measured by the efficiency of PSII, leaf area, succulence, height, root-to-shoot ratio, and total biomass. Clonal diversity was extremely low with one F. japonica clone and five F. ×bohemica genotypes. The two taxa were significantly different in several traits, but did not vary in biomass or plasticity of any trait. All traits were highly plastic in response to salinity, but differed significantly among genets. Despite this variation, plants from the salt marsh habitats did not perform better in the salt treatment, suggesting that they are not better adapted to tolerate salt. Instead, our data support the hypothesis that plasticity in salt tolerance traits may allow these taxa to live in saline habitats without specific adaptation to tolerate salt.     

春季-冻融交替时期9种落叶及半常绿小灌木抗寒性综合评价

在春季—冻融交替时期,以北京地区迎春、金叶女贞、小花溲疏等9种落叶及半常绿小灌木一年生枝条为试材,通过人工模拟降温,测定其在4 ~ -20℃低温胁迫下的6个生理响应指标,并对各指标进行相关性分析。结果表明,相对电导率、半致死温度、游离-脯氨酸含量和相对含水量这4个生理指标可作为9种小灌木抗寒性的评价指标。利用主成分分析、隶属函数法进行抗寒性综合评价,发现9种小灌木的抗寒性强弱顺序为：小花溲疏＞ 紫叶小檗＞ 太平花＞ 红王子锦带＞ 迎春＞ 连翘＞ 金叶女贞＞ 棣棠＞ 金山绣线菊。通过聚类分析可将9种小灌木分为3类,小花溲疏和紫叶小檗归为一类,其抗寒性相对较好;太平花、红王子锦带、迎春和连翘聚成一组,抗寒性一般;金叶女贞、棣棠和金山绣线菊聚在一起,抗寒性相对较差。     

Genetic and morphological analysis of Berberis microphylla G. Forst. accessions in southern Tierra del Fuego

Calafate (Berberis microphylla G. Forst.) is a spontaneous shrub grown in the Patagonian region, from which berries are traditionally harvested for different purposes. This study aims to investigate on the spatial genetic structure of calafate populations grown in southern Tierra del Fuego and their morphological and genetic diversity. A first step of the research focused on 23 putative populations screened by a landscape genetic approach based on 82 geo-referenced and Random Amplified Polymorphic DNA marker characterized plants. The second phase regarded the analysis of the morphological characteristics of fruits, shoots and leaves observed on a subset of 39 plants. Taking into account multiple similarity between pairs and sub-sets of accessions, the observed differences have been associated to geographical and environmental conditions. The results allowed to postulate the existence of homogeneous populations within the studied plant sets and to formulate hypothesis on the evolution of B. microphylla in that area. No association between genetic and morphologic distances of the accessions has been observed.     

Micropropagation systems for the mexican redbud (Cercis canadensis var. Mexicana L.) and other woody plants of the chihuahuan desert

Summary There are many Chihuahuan desert species that have potential as landscape plants for the arid communities of the southwestern United States [agarita, Berberis trifoliata Moric.; Mexican buckeye, Ungnadia speciosa Endl.; Texas madrone, Arbutus xalapensis var. texana (Buckl.). A. Gray]. Within these plant populations, there are superior genotypes that offer even greater interest for the landscape. However, it is difficult to clonally propagate many of these species with conventional techniques, and the seed-derived populations often do not breed true. Therefore, selection of superior genotypes in wild populations coupled with clonal propagation through tissue culture may offer an attractive option. It is relatively easy to achieve disinfestation of explants from desert plants due to a general lack of natural surface contamination by fungi and bacteria, even though interference from numerous trichomes can impede good contact with disinfesting agents. However, there is only a narrow window of time that is ideal for explant collection, because of the brief, periodic flushes of growth that characterize this unusual plant group. There may be years when, due to the harsh environment, the amount of suitable explant material is severely limited. Phenolics and exudates are also problematic in this group of plants, and acclimatization of ex vitro plantlets to the harsh desert environment is a particular challenge. For these reasons, specific adaptations and modifications were necessary to achieve success with micropropagation of desert plant species such as Mexican redbud (Cercis canadensis var. mexicana L.).     

Intercontinental dispersal prior to human translocation revealed in a cryptogenic invasive tree

In this study, complementary species-level and intraspecific phylogenies were used to better circumscribe the original native range and history of translocation of the invasive tree Parkinsonia aculeata. Species-level phylogenies were reconstructed using three chloroplast gene regions, and amplified fragment length polymorphism (AFLP) markers were used to reconstruct the intraspecific phylogeny. Together, these phylogenies revealed the timescale of transcontinental lineage divergence and the likely source of recent introductions of the invasive. The sequence data showed that divergence between North American and Argentinean P. aculeata occurred at least 5.7 million years ago, refuting previous hypotheses of recent dispersal between North and South America. AFLP phylogenies revealed the most likely sources of naturalized populations. The AFLP data also identified putatively introgressed plants, underlining the importance of wide sampling of AFLPs and of comparison with uniparentally inherited marker data when investigating hybridizing groups. Although P. aculeata has generally been considered North American, these data show that the original native range of P. aculeata included South America; recent introductions to Africa and Australia are most likely to have occurred from South American populations.     

Differences in functional traits among distinct populations of the plant invader Bunias orientalis

入侵植物疣果匙荠不同种群间的功能性状差异 特定环境下植物扩大领域入侵到其他区域时,其功能性状会发生改变。原产地环境已形成植物原有功能性状,当植物居住环境发生改变时,其功能性状亦会随之改变。本文旨在探讨居于常见条件与原产地气候条件的原状态、入侵状态、归化状态下不同疣果匙荠(Bunias orientalis)种群间的性状变异。自8个国家收集了12种疣果匙荠种子(每种状态各4种),将其种植于标准条件下的同质园中,并比较不同状态不同种类的物候、生长、繁殖等功能性状变化。 研究结果表明, 物候不因植物状态而异,但某些原产于常年低温地区的原状态植物并未开花。相比原状态植物,入侵状态植物的叶子更多,这表明了其在积累植被生物量上的活力。短角果的数量和质量,以及其他的生长性状在不同的状态间没有差异,但在不同种群间存在差异。一些功能性状的变异可能是由于原生地对当地条件的长期适应和遗传多样性所致,而其他环境因素在新环境下的差异可能导致了较高的性状变异。     

A Panax-centric view of invasive species

Plant-centric sampling provides a novel approach to quantifying the potential impact of invasive species on native plant species. The aim of this study was to determine the level of exposure of individuals and populations of Panax quinquefolius to invasive plant species using this approach in thirty natural ginseng populations. A high level of invasion was found with 63–70% of ginseng populations containing at least one invasive species. Approximately one-third of all individuals were found in close proximity to invasive plants. The most prevalent invasive species were Rosa multiflora and Berberis thunbergii. The exposure to invasives of plants in different size classes varied among populations. Invasive species presence increased with greater ginseng population sizes and presence of harvest. The abundance of invasives plants within forest interiors near this valuable medicinal herb suggests that the economic and ecological costs of competitive interactions with native species could be high.     

More than multiple introductions: Multiple taxa contribute to the genesis of the invasive California’s wild artichoke thistle

The history of some invasive species is so complex that their origins can be difficult to determine. One example of such invasive species is the California invasive known as “wild artichoke thistle” (Cynara cardunculus var. sylvestris), found in natural and disturbed ecosystems. Wild artichoke thistle is a Mediterranean native and the progenitor of two domesticated horticultural taxa, artichoke and cardoon. Different hypotheses regarding the origins of California plants have included introductions by 19th century Italian immigrants and the de-domestication (evolutionary reversion to wild-type morphology) of feral (escaped, free-living) cultivars. Using microsatellite markers, we compared the genetic constitutions of 12 artichoke thistle populations in California with possible progenitor populations: 17 Spanish and Italian wild populations and eight different artichoke and cardoon cultivars. Each California population was compared with its putative progenitors using STRUCTURE analysis. Our results suggest that California's artichoke thistle populations are polyphyletic. Surprisingly, two-thirds of California's populations closely matched populations from the Iberian Peninsula. Three populations matched domesticated artichoke. One population appears to have wild and cultivar hybrid ancestry. Alleles specific to Italian populations were found at low frequencies in some California plants, suggesting that Italian wild plants may have been in California, but have left a trivial genetic legacy. Given that the de-domesticated plants in this study appear to be as invasive as the wild taxon, we conclude with a discussion of the role that ferality and de-domestication may have in plant invasions.