Market potential for new vegetable varieties in Solomon Islands

A market study was conducted in the Solomon Islands in 2009. The objectives were to understand the current diversity of vegetables and the total volume of vegetables traded in the country, determine the potential for new vegetable varieties, and identify major varieties and traits that market vendors prefer. Quantitative data were gathered in Guadalcanal Province (Honiara central market) and Malaita Province (Auki market), from mid-November to mid- December. Results showed an annual volume of 2,631 metric tons sold in both markets valued at US$ 2.83 million, much lower than the estimated production volume of 6,506 metric tons in 2009. Although only about 20% of the vendors sold new varieties in the past, nearly 40% said that several vegetables with good market potential are currently missing in their areas. Reasons vary from production constraints (infertile soil, high incidence of insects, pests and diseases, excessive rain), lack of financial resources (high cost of production, high transportation cost, expensive seeds), no/poor access to resources (seeds, land, water), to seasonal availability (not available in the market when they want to sell it, insufficient quantities produced). The main vegetable varieties that vendors thought were better than the ones being sold and which they would be interested to try are: yardlong bean with green pods (79%), cabbage with dark green leaves (73%), and onion with white bulbs (50%)

Reduction of incubation time and enhancement of analyte adhesion uniformity of impedance biosensors using microvibration method

Electrochemical impedance spectroscopy (EIS) analysis can detect an analyte with high sensitivity inshort time. The self-assembled monolayer (SAM) technique is usually used for attaching analytes to atransducer. In general, the relatively time-consuming incubation time and the non-uniform immobilizationof an analyte on the sensing electrode are the commonly encountered problems. This study proposesa simple microvibration method based on Bernoulli’s theory for improving incubation time and enhancingthe adhesion uniformity of the analyte. The detection of the group-2 allergen Der p2 demonstratesthat a suitable applied frequency at a fixed amplitude can considerably reduce the sample preparationtime and improve the adhesion and adhesive uniformity of the analyte. It is also found that compared tothe conventional dipping method the microvibration method can give a relatively large detection range,provide a relatively better detection linearity, and result in a standard detection curve with a relativelylarge slope so that the sensitivity of the sensor can be increased and the detection error due to measurementvariations can be reduced. The proposed scheme can be further applied to other detection methodsthat use surface-bound reactions for analyte immobilization

Characterization of a Unique Chromosomal Copper Resistance Gene Cluster from Xanthomonas campestris pv. vesicatoria

We characterized the copper resistance genes in strain XvP26 of Xanthomonas campestris pv. vesicatoria, which was originally isolated from a pepper plant in Taiwan. The copper resistance genes were localized to a 7,652-bp region which, based on pulsed-field gel electrophoresis and Southern hybridization, was determined to be located on the chromosome. These genes hybridized only weakly, as determined by Southern analysis, to other copper resistance genes in Xanthomonas and Pseudomonas strains. We identified five open reading frames (ORFs) whose products exhibited high levels of amino acid sequence identity to the products of previously reported copper genes. Mutations in ORF1, ORF3, and ORF4 removed copper resistance, whereas mutations in ORF5 resulted in an intermediate copper resistance phenotype and insertions in ORF2 had no effect on resistance conferred to a copper-sensitive recipient in transconjugant tests. Based on sequence analysis, ORF1 was determined to have high levels of identity with the CopR (66%) and PcoR (63%) genes in Pseudomonas syringae pv. tomato and Escherichia coli, respectively. ORF2 and ORF5 had high levels of identity with the PcoS gene in E. coli and the gene encoding a putative copper-containing oxidoreductase signal peptide protein in Sinorhizobium meliloti, respectively. ORF3 and ORF4 exhibited 23% identity to the gene encoding a cation efflux system membrane protein, CzcC, and 62% identity to the gene encoding a putative copper-containing oxidoreductase protein, respectively. The latter two ORFs were determined to be induced following exposure to low concentrations of copper, while addition of Co, Cd, or Zn resulted in no significant induction. PCR analysis of 51 pepper and 34 tomato copper-resistant X. campestris pv. vesicatoria strains collected from several regions in Taiwan between 1987 and 2000 and nine copper-resistant strains from the United States and South America showed that successful amplification of DNA was obtained only for strain XvP26. The organization of this set of copper resistance genes appears to be uncommon, and the set appears to occur rarely in X. campestris pv. vesicatoria

Detection of allergies using a silver nanoparticle modified nanostructured biosensor

The IgE (Immunoglobulin E) in the serum of an asthma patient is a useful index for the detection of allergy diseases. In this study, a nanostructured biosensor with uniformly deposited gold nanoparticles (GNPs) is used as the sensing electrode for fast and low serum consuming detection of the IgE in an allergy patient’s serum. To enhance the charge transfer efficiency of the biosensor, silver nanoparticles (SNPs) were deposited on the GNP layer. The group 2 allergen, Der p2, was used to indicate IgE. To ensure the specificity of detection, affinity purified goat anti-human IgE antibody was further immobilized to the IgE. After immobilizing the anti-IgE, electrochemical impedance spectroscopy (EIS) analysis was implemented to examine the concentration of the target IgE which was displayed in terms of a Nyquist plot. Blood serum samples with known allergy levels detected by the commercially available ImmunoCAP were used for verification of the sensor results. It is observed that the difference in the charge transfer resistance ( Ret) between the Der p2 immobilized electrode and the anti-IgE bonded electrode for each individual serum sample closely correlates to its ImmunoCAP class. The blood serum detection results indicate that the presented nanostructured biosensor is able to detect a patient’s allergy level with low sample consumption, short sample preparation time, and quick processing

Bacterial wilt resistance in tomato, pepper, and eggplant: genetic resources respond to diverse strains in the Ralstonia solanacearum species complex

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienceBacterial wilt, caused by strains belonging to the Ralstonia solanacearum species complex, inflicts severe economic losses in many crops worldwide. Host resistance remains the most effective control strategy against this disease. However, wilt resistance is often overcome due to the considerable variation among pathogen strains. To help breeders circumvent this problem, we assembled a worldwide collection of 30 accessions of tomato, eggplant and pepper (Core-TEP), most of which are commonly used as sources of resistance to R. solanacearum or for mapping quantitative trait loci. The Core-TEP lines were challenged with a core collection of 12 pathogen strains (Core-Rs2) representing the phylogenetic diversity of R. solanacearum. We observed six interaction phenotypes, from highly susceptible to highly resistant. Intermediate phenotypes resulted from the plants’ ability to tolerate latent infections (i.e., bacterial colonization of vascular elements with limited or no wilting). The Core-Rs2 strains partitioned into three pathotypes on pepper accessions, five on tomato, and six on eggplant. A “pathoprofile” concept was developed to characterize the strain clusters, which displayed six virulence patterns on the whole set of Core-TEP host accessions. Neither pathotypes nor pathoprofiles were phylotype specific. Pathoprofiles with high aggressiveness were mainly found in strains from phylotypes I, IIB, and III. One pathoprofile included a strain that overcame almost all resistance sources