Orobanche cohenii (Orobanchaceae) a new species from Israel

Orobanche cohenii a new species belonging to Orobanche sect. Trionychon is described and illustrated from Mt. Hermon, Israel. Its relationships with the other species of Orobanche sect. Trionychon occurring in this area are examined

The status of Portulaca oleraceal in Tenerife, the Canary Islands

La recolección de material perteneciente a Portulaca oleracea y especies afines en Tenerife y algunas otras islas del archipiélago reavivó nuestro interés en este complejo poliploide. Con la intención de homogeneizar el tratamiento de los taxones relacionados a Portulaca oleracea L., se propone elevar el rango subespecífico de alguno de ellos a rango específico. Se describe por primera vez para la ciencia Portulaca canariensis. El estudio de Portulaca oleracea y especies afines en Tenerife y otras islas del archipiélago revelan los siguientes hechos: a. Tres niveles de ploidía (diploide, tetraploide y hexaploide) están presentes en las islas, b. Se observaron poblaciones simpátricas de especies diploides, de tetraploides, de tetraploides más hexaploides, de hexaploides y de diploides más tetraploides y hexaploides y c. Las especies tetraploides fueron las más frecuentes, seguidas de las diploides, siendo las hexaploides las menos frecuentes. Los resultados de los recuentos cromosómicos concuerdan con los estudios previos realizadosFollowing a comprehensive collection of Portulaca oleracea-related species in Tenerife and a few other Canary Island renewed interest this polyploidy complex led to another progress in its investigations. In order to equalize the treatment of the taxa related to Portulaca oleracea L., its subspecies are raised to the specific rank. A new species, P. canariensis is described. Our study of the Portulaca oleracea-related species found in Tenerife and a few other Canary Island reveal the following facts: a. The three ploidy levels (diploids, tetraploids, and hexaploids) are well represented there, b. Sympatric populations of diploid plus diploid, tetraploids plus tetraploids, tetraploids plus hexaploids, hexaploids plus hexaploids, and diploid plus tetraploid plus hexaploid were discovered there and c. The most frequent species found were tetraploid, then the diploid and the least were hexaploids. Chromosome count followed our findings in previous studies

Su alcune piante nuove delle Isole Pelagie

On some new plants to Pelagic islands (Straits of Sicily) \u2013 Fifteen vascular plants belonging to the families Aizoaceae, Amaryllidaceae, Asteraceae, Brassicaceae, Euphorbiaceae, Myoporaceae, Orobanchaceae, Oxalidaceae, Portulacaceae and Solanaceae are reported as new to one or both the major Pelagic islands. With the exception of Narcissus serotinus and Orobanche minor, they are non-native plants, probably of recent human introduction, mostly in areas heavily modified by man. Myoporum insulare, widely used for reforestation and for ornament, occurs also in sub and semi-natural environments

Collapsing granular suspensions

A 2D contact dynamics model is proposed as a microscopic description of a collapsing suspension/soil to capture the essential physical processes underlying the dynamics of generation and collapse of the system. Our physical model is compared with real data obtained from in situ measurements performed with a natural collapsing/suspension soil. We show that the shear strength behavior of our collapsing suspension/soil model is very similar to the behavior of this collapsing suspension soil, for both the unperturbed and the perturbed phases of the material.Comment: 7 pages, 5 figures, accepted for publication in EPJ

Biogenic crust dynamics on sand dunes

Sand dunes are often covered by vegetation and biogenic crusts. Despite their significant role in dune stabilization, biogenic crusts have rarely been considered in studies of dune dynamics. Using a simple model, we study the existence and stability ranges of different dune-cover states along gradients of rainfall and wind power. Two ranges of alternative stable states are identified: fixed crusted dunes and fixed vegetated dunes at low wind power, and fixed vegetated dunes and active dunes at high wind power. These results suggest a cross-over between two different forms of desertification

Microsatellites for the genus Cucurbita and an SSR-based genetic linkage map of Cucurbita pepo L.

Until recently, only a few microsatellites have been available for Cucurbita, thus their development is highly desirable. The Austrian oil-pumpkin variety Gleisdorfer Ölkürbis (C. pepo subsp. pepo) and the C. moschata cultivar Soler (Puerto Rico) were used for SSR development. SSR-enriched partial genomic libraries were established and 2,400 clones were sequenced. Of these 1,058 (44%) contained an SSR at least four repeats long. Primers were designed for 532 SSRs; 500 primer pairs produced fragments of expected size. Of these, 405 (81%) amplified polymorphic fragments in a set of 12 genotypes: three C. moschata, one C. ecuadorensis, and eight C. pepo representing all eight cultivar groups. On an average, C. pepo and C. moschata produced 3.3 alleles per primer pair, showing high inter-species transferability. There were 187 SSR markers detecting polymorphism between the USA oil-pumpkin variety “Lady Godiva” (O5) and the Italian crookneck variety “Bianco Friulano” (CN), which are the parents of our previous F2 mapping population. It has been used to construct the first published C. pepo map, containing mainly RAPD and AFLP markers. Now the updated map comprises 178 SSRs, 244 AFLPs, 230 RAPDs, five SCARs, and two morphological traits (h and B). It contains 20 linkage groups with a map density of 2.9 cM. The observed genome coverage (Co) is 86.8%

Genome-wide BAC-end sequencing of Cucumis melo using two BAC libraries

<p>Abstract</p> <p>Background</p> <p>Although melon (<it>Cucumis melo </it>L.) is an economically important fruit crop, no genome-wide sequence information is openly available at the current time. We therefore sequenced BAC-ends representing a total of 33,024 clones, half of them from a previously described melon BAC library generated with restriction endonucleases and the remainder from a new random-shear BAC library.</p> <p>Results</p> <p>We generated a total of 47,140 high-quality BAC-end sequences (BES), 91.7% of which were paired-BES. Both libraries were assembled independently and then cross-assembled to obtain a final set of 33,372 non-redundant, high-quality sequences. These were grouped into 6,411 contigs (4.5 Mb) and 26,961 non-assembled BES (14.4 Mb), representing ~4.2% of the melon genome. The sequences were used to screen genomic databases, identifying 7,198 simple sequence repeats (corresponding to one microsatellite every 2.6 kb) and 2,484 additional repeats of which 95.9% represented transposable elements. The sequences were also used to screen expressed sequence tag (EST) databases, revealing 11,372 BES that were homologous to ESTs. This suggests that ~30% of the melon genome consists of coding DNA. We observed regions of microsynteny between melon paired-BES and six other dicotyledonous plant genomes.</p> <p>Conclusion</p> <p>The analysis of nearly 50,000 BES from two complementary genomic libraries covered ~4.2% of the melon genome, providing insight into properties such as microsatellite and transposable element distribution, and the percentage of coding DNA. The observed synteny between melon paired-BES and six other plant genomes showed that useful comparative genomic data can be derived through large scale BAC-end sequencing by anchoring a small proportion of the melon genome to other sequenced genomes.</p

Jack of All Trades, Master of All: A Positive Association between Habitat Niche Breadth and Foraging Performance in Pit-Building Antlion Larvae

Species utilizing a wide range of resources are intuitively expected to be less efficient in exploiting each resource type compared to species which have developed an optimal phenotype for utilizing only one or a few resources. We report here the results of an empirical study whose aim was to test for a negative association between habitat niche breadth and foraging performance. As a model system to address this question, we used two highly abundant species of pit-building antlions varying in their habitat niche breadth: the habitat generalist Myrmeleon hyalinus, which inhabits a variety of soil types but occurs mainly in sandy soils, and the habitat specialist Cueta lineosa, which is restricted to light soils such as loess. Both species were able to discriminate between the two soils, with each showing a distinct and higher preference to the soil type providing higher prey capture success and characterizing its primary habitat-of-origin. As expected, only small differences in the foraging performances of the habitat generalist were evident between the two soils, while the performance of the habitat specialist was markedly reduced in the alternative sandy soil. Remarkably, in both soil types, the habitat generalist constructed pits and responded to prey faster than the habitat specialist, at least under the temperature range of this study. Furthermore, prey capture success of the habitat generalist was higher than that of the habitat specialist irrespective of the soil type or prey ant species encountered, implying a positive association between habitat niche-breadth and foraging performance. Alternatively, C. lineosa specialization to light soils does not necessarily confer upon its superiority in utilizing such habitats. We thus suggest that habitat specialization in C. lineosa is either an evolutionary dead-end, or, more likely, that this species' superiority in light soils can only be evident when considering additional niche axes