Physical mapping of ribosomal DNA and genome size in diploid and polyploid North African Calligonum species (Polygonaceae).

Most Calligonum species are desert plants, characteristic of the Saharan bioclimatic region. All species karyologically analyzed until present have the basic chromosome number x = 9 and comprise diploids, triploids and tetraploids. The Tunisian flora comprises diploid Calligonum arich and C. azel, of restricted distribution, and the tetraploid C. comosum with wider distribution. Analyses of their karyotypes and polyploidisation-linked rDNA changes by orcein staining, fluorochrome banding with chromomycin A3 and fluorescent in situ hybridisation with 5S and 26S ribosomal DNA probes have been performed. We report the chromosome number for Calligonum arich (2n = 18) as well as the diploid level for C. comosum for the first time. Chromosome counts have also verified the earlier described tetraploid cytotype (2n = 36) of C. comosum. A general pattern of six GC-rich bands as well as two 35S sites and four 5S sites is described for Calligonum species at the diploid level although there is intraspecific variation regarding the site number in a second type of C. comosum, with one pair of 35S rDNA sites and two pairs of 5S rDNA sites. The tetraploid cytotype of C. comosum has undergone locus loss and genome downsizing. Genome size assessments confirmed previous data. Nonetheless, statistically significant differences were found depending on the type of tissue used for estimation. Measurements from seeds had always larger values than from leaves. The presence of cytosolic compounds in leaves, interfering with DNA staining, is discussed as a possible cause of the differences

The role of botanical families in medicinal ethnobotany: a phylogenetic perspective

Studies suggesting that medicinal plants are not chosen at random are becoming more common. The goal of this work is to shed light on the role of botanical families in ethnobotany, depicting in a molecular phylogenetic frame the relationships between families and medicinal uses of vascular plants in several Catalan-speaking territories. The simple quantitative analyses for ailments categories and the construction of families and disorders matrix were carried out in this study. A Bayesian approach was used to estimate the over- and underused families in the medicinal flora. Phylogenetically informed analyses were carried out to identify lineages in which there is an overrepresentation of families in a given category of use, i.e., hot nodes. The ethnobotanicity index, at a specific level, was calculated and also adapted to the family level. Two diversity indices to measure the richness of reported taxa within each family were calculated. A total of 47,630 use reports were analysed. These uses are grouped in 120 botanical families. The ethnobotanicity index for this area is 14.44% and the ethnobotanicity index at the family level is 68.21%. The most-reported families are Lamiaceae and Asteraceae and the most reported troubles are disorders of the digestive and nutritional system. Based on the meta-analytic results, indicating hot nodes of useful plants at the phylogenetic level, specific ethnopharmacological research may be suggested, including a phytochemical approach of particularly interesting taxa

First genome size assessments in Carduncellus and its related genera Femeniasia and Phonus (Asteraceae, Cardueae), with data on 21 taxa

Genome size of 18 species of the genus Carduncellus, two species of the related genus Phonusand the monotypic genus Femeniasia (F. balearica) has been assessed by flow cytometry for the first time. Ploidy levels were assigned using genome size data together with previously reported chromosome counts. A phylogenetic framework was built to visualize how cytogenetic traits distributed across taxa. The results confirmed three ploidy levels (2x, 4x and 6x), with a predominance of diploids. The 2C values ranged from 3.24 pg in Carduncellus calvusto 11.16 pg in C. erio-cephalus, whereas monoploid genome size (1Cx) ranged from 1.29 pg in C. duvauxii (4x)to 2.30 pg in Phonus rhiphaeus (2x). The mean 1Cx for tetraploids was lower than for diploids. For each ploidy level, genome size values of Carduncellus, Femeniasia and Phonus were found to be higher than those of Carthamus. This result is consistent with a trend frequently observed in plants, of higher genome sizes in long life cycle taxa compared to short-lived relative

Key processes for Cheirolophus (Asteraceae) diversification on oceanic islands inferred from AFLP data

The radiation of the genus Cheirolophus (Asteraceae) in Macaronesia constitutes a spectacular case of rapid diversification on oceanic islands. Twenty species - nine of them included in the IUCN Red List of Threatened Species - have been described to date inhabiting the Madeiran and Canarian archipelagos. A previous phylogenetic study revealed that the diversification of Cheirolophus in Macaronesia started less than 2 Ma. As a result of such an explosive speciation process, limited phylogenetic resolution was reported, mainly due to the low variability of the employed molecular markers. In the present study, we used highly polymorphic AFLP markers to i) evaluate species' boundaries, ii) infer their evolutionary relationships and iii) investigate the patterns of genetic diversity in relation to the potential processes likely involved in the radiation of Cheirolophus. One hundred and seventy-two individuals representing all Macaronesian Cheirolophus species were analysed using 249 AFLP loci. Our results suggest that geographic isolation played an important role in this radiation process. This was likely driven by the combination of poor gene flow capacity and a good ability for sporadic long-distance colonisations. In addition, we also found some traces of introgression and incipient ecological adaptation, which could have further enhanced the extraordinary diversification of Cheirolophus in Macaronesia. Last, we hypothesize that current threat categories assigned to Macaronesian Cheirolophus species do not reflect their respective evolutionary relevance, so future evaluations of their conservation status should take into account the results presented here

Recent updates and developments to plant genome size databases

Two plant genome size databases have been recently updated and/or extended: the Plant DNA C-values database (http://data.kew.org/cvalues), and GSAD, the Genome Size in Asteraceae database (http://www.asteraceaegenomesize.com). While the first provides information on nuclear DNA contents across land plants and some algal groups, the second is focused on one of the largest and most economically important angiosperm families, Asteraceae. Genome size data have numerous applications: they can be used in comparative studies on genome evolution, or as a tool to appraise the cost of whole-genome sequencing programs. The growing interest in genome size and increasing rate of data accumulation has necessitated the continued update of these databases. Currently, the Plant DNA C-values database (Release 6.0, Dec. 2012) contains data for 8510 species, while GSAD has 1219 species (Release 2.0, June 2013), representing increases of 17 and 51%, respectively, in the number of species with genome size data, compared with previous releases. Here we provide overviews of the most recent releases of each database, and outline new features of GSAD. The latter include (i) a tool to visually compare genome size data between species, (ii) the option to export data and (iii) a webpage containing information about flow cytometry protocols

Physical mapping of ribosomal DNA and genome size in diploid and polyploid North African Calligonum species (Polygonaceae).

Most Calligonum species are desert plants, characteristic of the Saharan bioclimatic region. All species karyologically analyzed until present have the basic chromosome number x = 9 and comprise diploids, triploids and tetraploids. The Tunisian flora comprises diploid Calligonum arich and C. azel, of restricted distribution, and the tetraploid C. comosum with wider distribution. Analyses of their karyotypes and polyploidisation-linked rDNA changes by orcein staining, fluorochrome banding with chromomycin A3 and fluorescent in situ hybridisation with 5S and 26S ribosomal DNA probes have been performed. We report the chromosome number for Calligonum arich (2n = 18) as well as the diploid level for C. comosum for the first time. Chromosome counts have also verified the earlier described tetraploid cytotype (2n = 36) of C. comosum. A general pattern of six GC-rich bands as well as two 35S sites and four 5S sites is described for Calligonum species at the diploid level although there is intraspecific variation regarding the site number in a second type of C. comosum, with one pair of 35S rDNA sites and two pairs of 5S rDNA sites. The tetraploid cytotype of C. comosum has undergone locus loss and genome downsizing. Genome size assessments confirmed previous data. Nonetheless, statistically significant differences were found depending on the type of tissue used for estimation. Measurements from seeds had always larger values than from leaves. The presence of cytosolic compounds in leaves, interfering with DNA staining, is discussed as a possible cause of the differences

Cheirolophus intybaceus (Asteraceae, Centaureinae) o la constància del valor 2C

Cheirolophus intybaceus es una especie heliófila propia de los matorrales mediterráneos termófilos que crece en una franja litoral de unos 50 km de anchura que va desde Tolón (Var, Francia) hasta el sur de la península Ibérica, estando también presente en las islas Baleares (excepto en Menorca). Se encuentra también en las zonas elevadas y soleadas de las cuencas fluviales mediterráneas, formando un complejo de táxones estrechamente relacionados entre sí. Los objetivos de este trabajo son: i) contribuir a la aportación de datos de tamaño del genoma para diversas especies de Asteraceae; ii) estudiar la variación de la cantidad de ADN a lo largo del área de distribución de una especie; iii) evaluar la capacidad de discriminación de este parámetro a niveles taxonómicos bajos. Se ha encontrado una correlación positiva y significativa entre la cantidad de ADN y la latitud, es decir, que en hábitats con menor pluviosidad y más cálidos el tamaño del genoma tiende a disminuir en esta especie. La variación en todo el área de distribución de Ch. intybaceus es de 1,15 veces. Nos encontramos, por lo tanto, ante un caso de baja variabilidad que apoya la constancia del valor 2C

Molecular cytogenetic characterization of some representatives of the subgenera Artemisia and Absinthium (genus Artemisia, Asterraceae)

Se ha llevado a cabo un estudio citogenético molecular en tres especies del género Artemisia, que complementa trabajos previos sobre dos subgéneros que han sido poco estudiados desde este punto de vista, Artemisia (A. chamaemelifolia, A. vulgaris) y Absinthium (A. absinthium). Se han efectuado tinciones de bandeo con cromomicina A3 y con 4',6-diamidino-2-fenilindol (DAPI), así como hibridación in situ fluorescente (FISH) del ADN ribosómico 5S y 18S-5.8S-26S. Se han calculado los datos morfométricos relativos a los caracteres del cariotipo y se han construido los idiogramas con indicación de la posición de las regiones ricas en AT y GC y los loci del ADNr. Se ha observado la colocalización de la mayoría de estas regiones; tal como se había mencionado en otros estudios sorbe el género, ambos ADN ribosómicos aparecen siempre colocalizados, lo que constituye un rasgo distintivo con respecto de la mayor parte de angiospermas. En cuanto a las características diferenciales de cada especie, A. absinthium muestra cromosomas largos, un cariotipo simétrico y carece de bandas centroméricas, que, por el contrario, aparecen en A. chamaemelifolia y A. vulgaris. La última especie presenta, además, cromosomas B en los que se ha detectado ADN ribosómico y heterocromatina. A pesar de estas diferencias, la morfología del cariotipo y el modelo de bandas de las tres especies son muy similares. Esto puede reflejar una relación filogenética estrecha entre ambos subgéneros, lo que es coherente con las filogenias moleculares hasta ahora publicadas para el género, que presentan mezcladas especies de los subgéneros Artemisia y Absinthium