“Barcoding” and ISSR data illuminate a problematic infraspecific taxonomy for Chrysanthemoides monilifera (Calenduleae; Asteraceae): Lessons for biocontrol of a noxious weed

Chrysanthemoides monilifera Tourn. ex Medik is a noxious weed in Australia and New Zealand. It is a widespread species in southern Africa, where it shows considerable morphological variation that has resulted in a confusing infraspecific taxonomy. We use DNA sequence data from the nuclear Internal Transcribed Spacer (ITS) region from 78 samples of this species from its indigenous distribution range and 10 samples from Australia and New Zealand to determine the regions of origin of the invasive plants. These data are augmented by a smaller study using ISSR markers. Bayesian Inference analysis was somewhat resolved, with many weakly supported nodes. Clades with support tended to correspond to infraspecific taxonomic entities, and were geographically coherent. In contrast, a neighbour-net analysis was not as well resolved and indicated considerable reticulation. All analyses of ITS data retrieved two major clades corresponding to Western and Eastern distributions, with some overlap. Samples from New Zealand and Australia correspond to the taxon C. monilifera subsp. monilifera, and are resolved as most closely related to samples from the greater Cape Town area. Biological control agent populations for C. monilifera subsp. monilifera should be sourced from this region in order to avoid host plant incompatibility problems.     

Detection of coccidioidal antibodies in serum of a small rodent community in Baja California,Mexico

Coccidioidomycosis (Valley Fever) represents a serious threat to inhabitants of endemic areas of North America. Despite successful clinical isolations of the fungal etiological agent, Coccidioides spp., the screening of environmental samples has had low effectiveness, mainly because of the poor characterization of Coccidioides ecological niche. We explored Valle de las Palmas, Baja California, Mexico, a highly endemic area near the U.S.–Mexico border, where we previously detected Coccidioides via culture-independent molecular methods. By testing the serum from 40-trapped rodents with ELISA, we detected antibodies against Coccidioides in two species: Peromyscus maniculatus and Neotoma lepida. This study comprises the first report of wild rodent serum tested for coccidioidal antibodies, and sets the basis to analyze this pathogen in its natural environment and explore its potential ecological niche.     

How to Use Genetic Data to Distinguish Between Natural and Human-Mediated Introduction of <Emphasis Type="Italic">Littorina littorea</Emphasis> to North America

The rapid range southward expansion of the periwinkle Littorina littorea from the Canadian maritimes has fueled a long-running debate over whether this species was introduced to North America by human activity. A reappraisal of the mitochondrial DNA sequence evidence finds considerable endemic allelic diversity in the American population. The degree of endemic genetic diversity is higher than expected from human-mediated colonization, but not so much to suggest that it survived the last glacial maximum in America. Coalescent estimates of population divergence agree that colonization of America preceded European contact. A reappraisal of the ITS nuclear sequence data finds extensive recombination. Taking this recombination into account strengthens the genetic case against human-mediated introduction. Finally, a reappraisal of conflicting allozyme studies from the 1970’s supports a claim of limited divergence between American and European populations. This is consistent with post-glacial colonization, but the allozyme data cannot distinguish between natural or human-mediated colonization. Taken as a whole, the DNA sequence data supports the many sub-fossil reports of an American L. littorea population in the Canadian maritimes that preceded even the first visits by the Vikings.     

Loop‐mediated isothermal amplification (LAMP) for the identification of invasive Aedes mosquito species

Invasive Aedes mosquito species (Diptera: Culicidae) are of public health concern in Europe because they are either recognized or potential vectors of pathogens. Loop‐mediated isothermal amplification (LAMP) is a rapid and simple method for amplifying DNA with high specificity and efficiency, with the technique having potential for application in the field, including in high‐throughput format. Specific LAMP assays based on rDNA internal transcribed spacers 1 or 2 sequences, considering intraspecies variability at these loci, were developed for Aedes aegypti, Aedes albopictus, Aedes japonicus, Aedes koreicus and the indigenous Aedes geniculatus. No such assays could be developed for Aedes atropalpus and Aedes triseriatus because both loci were too short to serve as target. The assays rely on the clearly visible colour change from violet to sky blue after successful amplification. Sensitivity of egg detection was confirmed with ratios of up to one mosquito egg in 99 other eggs. Simple sample preparation of adults or eggs by mechanical homogenization in water required an additional heat treatment or centrifugation step to avoid non‐specific colour changes. Thus, further technical improvements are needed to render these assays truly field‐applicable, which would greatly facilitate surveillance of these invasive mosquito species and allow for prompt implementation of control measures.     

The generic placement of a morphologically enigmatic species in Asteraceae: evidence from ITS sequences

 Bidens cordylocarpa is a high polyploid species restricted in distribution to stream sides in the mountains of Jalisco, Mexico. The morphologically enigmatic species was originally described as a member of the genus Coreopsis, but later transferred to Bidens, largely because the involucral bracts appear most similar to Bidens. Characters of the cypselae, often useful in generic placement, are of no value for this species because the fruits have features not detected in either Bidens or Coreopsis. Sequences from the internal transcribed spacer region of nuclear ribosomal DNA (ITS) were used to assess the relationships of Bidens cordylocarpa. The molecular phylogeny places B. cordylocarpa in a strongly supported clade of Mexican and South American Bidens, and provides more definitive evidence of relationships than morphology, chromosome number, or secondary chemistry. Molecular, morphological, and chromosomal data suggest that B. cordylocarpa is an ancient polyploid, perhaps the remnant of a polyploid complex. Received August 28, 2000 Accepted February 11, 2001     

ITS2 barcode for identifying the officinal rhubarb source plants from its adulterants

Officinal rhubarb, the dried root and rhizome of Rheum officinale Baill., Rh. palmatum L., and Rh. tanguticum (Maxim. ex Regel) Maxim. ex Balf. of Polygonaceae family, is one of the most well-known and important traditional Chinese medicines. The growing herbal market has led to the introduction of adulterants, and difficulties in morphological based discrimination has also resulted in concerns over consumer safety. ITS2 as a potential barcode was employed to discriminate officinal rhubarb sampled from the entire distribution range and its adulterants. The minimum K2P interspecific distance between officinal rhubarb source plants and the adulterants were higher than the maximum K2P intraspecific distance within the officinal rhubarb source plants. When the phylogenetic trees were constructed by neighbor joining (NJ), maximum parsimony (MP), maximum likelihood (ML) and Bayesian methods, all Rheum species were grouped into one clade, while Polygonum and Rumex species were clustered in another clade. In the Rheum clade, all the officinal rhubarb source plants constituted a distinct subclade, while other Rheum species formed other subclades. Our results suggested that the ITS2 region is a more suitable and accurate DNA barcode for distinguishing officinal rhubarb source plants from their adulterants.     

Molecular approach to the phylogeny and systematics of Cytisus (Leguminosae) and related genera based on nucleotide sequences of nrDNA (ITS region) and cpDNA (trnL-trnF intergenic spacer)

 Phylogenetic relationships of Cytisus and allied genera (Argyrocytisus, Calicotome, Chamaecytisus, Cytisophyllum, and Spartocytisus) were assessed by analysis of sequences of the nrDNA internal transcribed spacer (ITS) and the cpDNA trnL-trnF intergenic spacer. Genera of the Genista-group (Chamaespartium, Echinospartum, Genista, Pterospartum, Spartium, Teline and Ulex) were included to check the position of Cytisus species transferred to Teline. The tree obtained by combining both sets of data indicates that the Genista and Cytisus groups form two separate clades. Cytisus heterochrous and C. tribracteolatus are more closely related to the Cytisus-group, thus their transfer to Teline is not supported by molecular data. Cytisus fontanesii (syn. Chronanthos biflorus) groups with Cytisophyllum sessilifolium and Cytisus heterochrous within the Cytisus-group. Similarly, Argyrocytisus battandieri falls within the Cytisus-group as a well differentiated taxon. All these taxa seem to have early diverged from the Cytisus-group. Their taxonomic rank should be reconsidered to better reflect their phylogenetic separation from Cytisus. On the contrary, Chamaecytisus proliferus and Spartocytisus supranubius enter in the main core of Cytisus, and they should better be included in sections of Cytisus (sect. Tubocytisus and Oreosparton, respectively). Sect. Spartopsis is not monophyletic and the position of several species, currently included in this section, deserves reevaluation: C. arboreus aggregate is closely related to C. villosus (sect. Cytisus) and to Calicotome; C. striatus is closely related to Cytisus sect. Alburnoides; and the position of C. commutatus (incl. C. ingramii) remains unclear. The relationships and positioning of several minor taxa (C. transiens, C. megalanthus, and C. maurus) are also discussed. Received November 22, 2001; accepted March 16, 2002 Published online: October 14, 2002 Addresses of the authors: Paloma Cubas (e-mail: cubas@farm.ucm.es) and Cristina Pardo (e-mail: cpardo@farm.ucm.es), Departamento de Biología Vegetal II, Facultad de Farmacia, Universidad Complutense, E-28040 Madrid, Spain. Hikmat Tahiri Faculté des Sciences, Université Mohammed V, BP 1014 Rabat, Morocco (e-mail: tahiri@ fsr.ac.ma).