Construction of Chromosome Segment Substitution Lines in Peanut (Arachis hypogaea L.) Using a Wild Synthetic and QTL Mapping for Plant Morphology

Chromosome segment substitution lines (CSSLs) are powerful QTL mapping populations that have been used to elucidate the molecular basis of interesting traits of wild species. Cultivated peanut is an allotetraploid with limited genetic diversity. Capturing the genetic diversity from peanut wild relatives is an important objective in many peanut breeding programs. In this study, we used a marker-assisted backcrossing strategy to produce a population of 122 CSSLs from the cross between the wild synthetic allotetraploid (A. ipaënsis×A. duranensis)^4x and the cultivated Fleur11 variety. The 122 CSSLs offered a broad coverage of the peanut genome, with target wild chromosome segments averaging 39.2 cM in length. As a demonstration of the utility of these lines, four traits were evaluated in a subset of 80 CSSLs. A total of 28 lines showed significant differences from Fleur11. The line×trait significant associations were assigned to 42 QTLs: 14 for plant growth habit, 15 for height of the main stem, 12 for plant spread and one for flower color. Among the 42 QTLs, 37 were assigned to genomic regions and three QTL positions were considered putative. One important finding arising from this QTL analysis is that peanut growth habit is a complex trait that is governed by several QTLs with different effects. The CSSL population developed in this study has proved efficient for deciphering the molecular basis of trait variations and will be useful to the peanut scientific community for future QTL mapping studies.     

Is livestock grazing compatible with amphibian diversity in the High Mountains of Córdoba, Argentina?

The High Mountains of Córdoba, Argentina have a long evolutionary history of grazing by large herbivores. However, about 400?years ago, European livestock were introduced and gradually replaced native herbivores. Since the 1920s, domestic herbivores have been the only large herbivores present in the area, causing severe soil erosion and a threat to the system diversity. The endemic fauna of the region includes four amphibian species. We evaluated the effect of livestock rearing on amphibian diversity and water bodies in woodlands and grasslands of the High Mountains of Córdoba. The work was conducted on stream stretches and ponds in two contrasting grazing situations: an area with livestock presence and another area where livestock was excluded 14?years ago. The following variables were recorded at each sampling site: amphibian richness and abundance, percentage of emergent, submerged and peripheral vegetation in areas surrounding the water bodies, water pH, and water dissolved O₂. No significant differences were detected in amphibian diversity between streams of both grazing situations, whereas a greater diversity (p?<?0.01) was observed in ponds in grazed grasslands. Our results suggest that livestock rearing, qualitatively measured as grazing and 14?years of livestock exclusion, in the study area would not have negative effects on amphibian diversity. This finding might be due to the long evolutionary grazing history of the area, large-scale livestock exclusion exhibiting a novel scenario. The ongoing reintroduction of native grazers may provide the benefits of grazing without the consequent soil erosion and habitat degradation associated with domestic livestock.     

Home range of greater and lesser rhea in Argentina : relevance to conservation

In this work we report results of radiotracking studies on the movements and home range sizes of two near-threatened species, the greater rhea (Rhea americana) and the lesser rhea (Pterocnemia pennata pennata) in relation to different land use regimes. We radiomonitored greater and lesser rheas for 3 years in their respective habitats: the Pampas and the Patagonia regions. We chose two study areas in each habitat with similar agricultural activities and different hunting control. We did not find significant differences in movements and home range size between study areas of each species. This suggests that disturbance caused by human presence in the areas did not affect rhea spacing behaviors. Moreover, lesser rheas showed larger home range and movements than greater rheas, showing that the home range size is not an immutable property of body mass, and that abundance and distribution of food appears to be the main factor that influences the movements and home range size of these birds.     

Low temperature induces the delivery of mature and immature CFTR to the plasma membrane

Deletion of phenylalanine 508 (ΔF508) is the most prevalent disease-causing mutation resulting in retention of the immature CFTR in the endoplasmic reticulum. The most common strategy to induce the delivery of ΔF508-CFTR to the surface of cells is by reducing the incubation temperature (≈28 °C). Cell surface biotinylation of HEK293T cells grown at 37 °C for 48 h, confirmed the presence of mature wild-type CFTR, but not ΔF508-CFTR at the cell surface. On the other hand, cells incubated at 28 °C for 16 h showed both mature and immature ΔF508-CFTR at their surface. The trafficking of immature ΔF508-CFTR, but not mature ΔF508-CFTR, to the cell surface occurred at low temperature even upon addition of BFA, suggesting the involvement of a Golgi-independent pathway. These results suggest that low temperature induces the appearance of a mix population of mature and immature CFTR molecules at the plasma membrane through distinct pathways.     

Rank Difference Analysis of Microarrays (RDAM), a novel approach to statistical analysis of microarray expression profiling data

Background  

A key step in the analysis of microarray expression profiling data is the identification of genes that display statistically significant changes in expression signals between two biological conditions.     

ABCG transporters export cutin precursors for the formation of the plant cuticle

1. Download : Download high-res image (193KB)
2. Download : Download full-size image