Sampling variation in genetic resources of seed crops: a review

Summary The first explorations for the collection of genetic resources of crop plants took place in areas designated as centers of origin. Later, important characters were found to be present in areas other than those indicated by Vavilov. Hence collection missions were extended to cover other areas in addition to the centers of diversity with different ecogeography and agromorphological features. Collecting activities were aimed not only at providing germplasm for immediate use in breeding but also at conserving genetic variation for future contingencies. The analysis of the collected material has revealed the complex nature, amount and distribution of genetic variation present in natural populations as well as in landraces, old varieties and primitive forms. The study of variation for characters from different regions indicated that it is possible to select certain characters for detecting variability in the populations and establishing the minimum number of genotypes to be sampled. A minimum number of 20–130 plants per sample, depending on the crop, is recommended in order to capture 95% of the total variation in the field. However, it has been emphasized that the number of different populations sampled rather than the sample size per population determines the overall efficiency of a collection. The findings reported allow better utilization of the collected material and formulation of optimal and cost-effective sampling strategies for the future.     

RFLP analysis of Aegilops species belonging to the Sitopsis section

The phylogenetic relationships among theAegilops species belonging to the Sitopsis section were investigated using RFLP (restriction-fragment-length polymorphism) analysis. Twenty-five probes, each of which hybridised to oneor more restriction fragments located in the B-genomechromosomes of cultivated wheats, were used. At least one and in most cases two fragments were located in every B genome chromosome arm. Adendrogram derived from a cluster analysis of the complete RFLP dataset showed a subdivision of the species belonging to the Sitopsis section into one group comprising the species of the Truncata subsection and another group comprised of the species of theEmarginata subsection. Dendrograms also were produced using RFLP data from loci located in different combinations of only three chromosomes, and some of these showed different subdivisions of the species. This demonstrates the importance in obtaining reliable classification data of using probes that detect loci evenly distributed in the genome and located in each chromosomearm.     

Genetic variation of the durum wheat landrace Haurani from different agro-ecological regions

The durum wheat landrace Haurani (Triticum durum Desf.) is grown under contrasting climatic regions of Syria from Deir Ezzor, in the North-East (230 m altitude, 150 mm mean annual rainfall), to Qunaytra, in the South-West (1060 m altitude, 825 mm mean annual rainfall). In order to assess the genetic variation between and within Haurani populations, samples from eight provinces of Syria (Daraa, Damascus, Qunaytra, Deir Ezzor, Hassakeh, Aleppo, Homs and Hama) were analysed by RFLPs and seed storage proteins of glutenin subunits as markers. The analyses showed the presence of genetic polymorphisms in all populations with the highest values in those from Homs and Hassakeh. Moreover, the results point out differences in genetic distances between populations; some populations were further apart, such as Damascus and Aleppo, whereas others were closer to each other, for instance Homs and Hama. Cluster analysis identified two distinct groups of populations, characterized by geographical proximity, with similar rainfall and altitude. It is suggested that the similarity of landraces at locations close to each other might be the result of more frequent seed exchanges between farmers or of gene flow due to 5% estimated outcross rate of Haurani.     

Effects of n-3 Polyunsaturated Fatty Acids (ω-3) Supplementation on Some Cardiovascular Risk Factors with a Ketogenic Mediterranean Diet

Background: the ketogenic diet (KD) has become a widely used nutritional approach for weight loss. Some of the KD’s positive effects on metabolism and cardiovascular risk factors are similar to those seen after n-3 polyunsaturated fatty acids (ω-3) supplementation. We hypothesized that a ketogenic Mediterranean diet with phytoextracts combined with ω-3 supplementation may have increased positive effects on cardiovascular risk factors and inflammation. Methods: We analyzed 34 male overweight subjects; aged between 25 and 65 years who were overall healthy apart from overweight. The subjects followed a ketogenic diet protocol for four weeks; with (KDO3) or without (KD) ω-3 supplementation. Results: All subjects experienced a significant loss of body weight and body fat and there was no significant differences between treatment (body weight: KD—4.7 kg, KDO3—4.03 kg, body fat KD—5.41 kg, KDO3—5.86 kg). There were also significant decreases in total cholesterol, LDL-c, and glucose levels. Triglycerides and insulin levels decreased more in KDO3 vs. KD subjects, with a significant difference. All the investigated inflammatory cytokines (IL-1β, IL-6, TNF-α) decreased significantly in KDO3 subjects whilst only TNF-α showed a significant decrease in KD subjects over the 12 month study period. No significant changes were observed in anti-inflammatory cytokines (IL-10 and IL-1Ra), creatinine, urea and uric acid. Adiponectin increased significantly only in the KDO3 group. Conclusions: ω-3 supplementation improved the positive effects of a ketogenic Mediterranean diet with phytoextracts on some cardiovascular/metabolic risk factors and inflammatory state.     

Somatic cell mating and segregation in chimeric frogs

Both pentaploid and haploid cells were observed in a short-term culture of bone marrow of a diploid-triploid frog chimera. Apparently, diploid and triploid marrow cells fused to form "hybrid" pentaploid cells, which subsequently gave rise by somatic reduction to haploid daughter cells. The hybrid marrow cells and their haploid segregants are presumably at a selective disadvantage, as neither type of cell has been detected in the circulating blood of chimeric frogs.     

Generation of leaf shape through early patterns of growth and tissue polarity

A major challenge in biology is to understand how buds comprising a few cells can give rise to complex plant and animal appendages like leaves or limbs. We address this problem through a combination of time-lapse imaging, clonal analysis, and computational modeling. We arrive at a model that shows how leaf shape can arise through feedback between early patterns of oriented growth and tissue deformation. Experimental tests through partial leaf ablation support this model and allow reevaluation of previous experimental studies. Our model allows a range of observed leaf shapes to be generated and predicts observed clone patterns in different species. Thus, our experimentally validated model may underlie the development and evolution of diverse organ shapes.     

Gap disturbances and regeneration patterns in a Bosnian old-growth forest: a multispectral remote sensing and ground-based approach

Objectives

We examined canopy gap structure and regeneration patterns at the landscape scale using a combination of remote sensing and field-based surveys.

Methods

The study was carried out in the forest reserve of Lom, an old-growth Fagus-Abies-Picea forest located within the Dinaric Alps in the north-western part of Bosnia and Herzegovina. A high-resolution (1-m panchromatic and 4-m multispectral) Kompsat-2 satellite image was orthorectified and classified through an unsupervised pixel-based classification using an artificial neural network method.

Results

This approach allowed the identification of 650 canopy gaps, ranging in size from 32 to 1,776?m². Only 20 intermediate to large gaps (>250?m²) were identified, and they were mainly present near the perimeter of the reserve. The origin of these large openings was associated with past human-caused disturbances or topographic conditions. The species composition of regeneration within large, human-caused gaps differed markedly from small gaps and non-gap sites in the core area of the reserve. Shade-intolerant species dominated the seedling and sapling layers in large openings. The landscape approach employed in this study confirmed the hypothesis that small gaps predominate at Lom, especially within the core area of the reserve.     

Snow gliding and loading under two different forest stands: a case study in the north-western Italian Alps

The presence of a thick snowpack could interfere with forest stability, especially on steep slopes with potential damages for young and old stands. The study of snow gliding in forests is rather comple...     

Flavonoids of white lupin roots participate in phosphorus mobilization from soil

The impact of flavonoids released by phosphorus-deficient white lupin roots on inorganic P and soil microorganisms is largely unknown. We report that flavonoids isolated from white lupin roots mobilized inorganic phosphorus and decreased soil microbial respiration, citrate mineralization, and soil phosphohydrolase activities, but did not reduce the soil ATP content. The results suggest that white lupin's release of flavonoids into the rhizosphere plays a significant role in its efficient P-acquisition strategy by solubilizing Fe-bound P and by limiting the microbial mineralization of citrate.