Wild-weed-crop complexes of common bean (Phaseolus vulgaris L., Fabaceae) in the Andes of Peru and Colombia, and their implications for conservation and breeding

During germplasm explorations carried out in Peru and Colombia, interbreeding complexes of wild and cultivated common bean were observed in both countries, eight in Apurimac and Cusco departments of Peru and eight in Cundinamarca and Boyaca´ departments of Colombia. The existence of complexes was evidenced both by segregation of wild and cultivated morphological traits in certain populations, and by the presence of genetically stabilized weedy types which were assumed to have arisen from past hybridization. Observations on phaseolin seed protein confirmed that genetic exchange was occurring. Phaseolin types introduced from other regions were in incipient stages of introgression into local populations. On the other hand, local phaseolin types were observed in all phases of the complexes from totally wild to fully cultivated beans, suggesting that the complexes had undergone a long evolution. Complexes could be an effective means to generate genetic variability, introgressing genes from wild populations into cultivated types and complementing modern plant breeding programs. The conservation of such complexes depends on the continued existence of the wild, weedy and cultivated beans in close proximity; on the maintenance of a semi-domesticated environment; and on the willingness of farmers to leave weedy types in the field.     

Seasonality in rooting of Prosopis chilensis cuttings and in-vitro micropropagation

Seasonality in rooting of cuttings and its relationship with some environmental conditions and growth parameters of Prosopis chilensis (Mol. Stunz) were studied. It was observed that rooting could be induced in cuttings taken from field collections only during the dry season, the period corresponding to the highest vegetative growth and reproductive activity (September to March); however, percentages did not exceed 15%. The rooting response does not occur during the dormant period (May to September). When using cuttings from clonal material growing in the glasshouse, rootings exceeding 80% were obtained in liquid aerated media.

In-vitro micropropagation was assessed in P. chilensis using nodal and apical segments collected both from the field and from clonal material and plantlets grown from seed in the glasshouse. Juvenile material gave an 80% regeneration rate of complete plants in Murashige-Skoog medium fortified with 5 mg naphtaleneacetic acid 1⁻¹ and 10 mg cysteine 1⁻¹. In this same medium, the regenerative response of segments obtained from rooted cuttings was 60%. The material collected from the field showed no rooting responses.     

Evaluation of safety and efficacy of DNA vaccines against bovine herpesvirus-1 (BoHV-1) in calves

Four DNA vaccines against BoHV-1 were evaluated for their efficacy in calves. Twelve animals were divided into four groups which were injected with four different DNA vaccines: pVAX-tgD (Vaccine A); pVAX-tgD co-immunised with pVAX-48CpG (Vaccine B); pVAX-UbiLacI-tgD-L (Vaccine C); pVAX-UbiLacI-tgD-L co-immunised with pVAX-48CpG (Vaccine D). Three additional calves were given the plasmid vector and served as controls. Ninety days after the first vaccination all calves were challenge infected with BoHV-1.All animals developed a severe form of infections bovine rhinotracheitis. Only the calves given the pVAX-tgD co-immunised with pVAX-48CpG (Vaccine B) developed humoral antibodies against BoHV-1 between 56 and 90 days after the first vaccination, whereas in calves of other groups and in the controls, antibodies appeared only after the infection. In the calves vaccinated with either pVAX-tgD (Vaccine A) or pVAX-tgD combined with pVAX-48CpG (Vaccine B), BoHV-1-specific IFN-γ secreting cells were detected in PBMCs 90 days after the first vaccination and their number increased after challenge exposure. In the other groups the IFN-γ secreting cells were detected after virus infection and at low values.     

Lignin changes after steam explosion and laccase-mediator treatment of eucalyptus wood chips

Eucalyptus globulus chips were steam exploded followed by treatment with a laccase-mediator system (LMS) under different experimental conditions. Removal of hemicelluloses and, to a lesser extent, lignin was observed. Thermogravimetic analyses of whole meal obtained from chips before and after steam explosion indicated an increase in lignin degradation temperature due to lignin condensation. In contrast, application of LMS treatment caused a reduction in lignin and polysaccharide degradation temperatures. Lignins were isolated from wood samples before and after each treatment and analyzed by 2D NMR and (13)C NMR. An increase in carboxyl and phenolic hydroxyl groups and a significant decrease in β-O-4 structures were found in steam-exploded samples. The most relevant changes observed after laccase treatment were increased secondary OH and degree of condensation.     

An experimental set‐up to study carbon,water, and nitrate uptake rates by hydroponically grown plants

The experimental system described allows concomitant hourly measurements of CO₂, H₂O, and NO₃ uptake rates by plants grown hydroponically in a greenhouse. Plants are enclosed in an airtight chamber through which air flows at a controlled speed. Carbon dioxide exchange and transpiration rates are determined from respective differences of concentrations of CO₂ and water vapor of the air at the system inlet and outlet. This set‐up is based on the “open‐system”; principle with improvements made on existing systems. For instance, propeller anemometers are used to monitor air flow rates in the chamber. From their signal it is possible to continuously adjust air speed to changing environmental conditions and plant activity. The air temperature inside the system therefore never rises above that outside. Water and NO₃ uptake rates are calculated at time intervals from changes in the volume and the NO₃ concentration of the nutrient solution in contact with the roots. The precise measurement of the volume of solution is achieved using a balance which has a higher precision than any liquid level sensors. Nitrate concentration is determined in the laboratory from aliquots of solution sampled at time intervals. A number of test runs are reported which validate the measurements and confirm undisturbed conditions within the system. Results of typical diurnal changes in CO₂, H₂O, and NO₃ uptake rates by fruiting tomato plants are also presented.     

Genetic diversity, conservation, and utilization of Theobroma cacao L.: genetic resources in the Dominican Republic

Cacao (Theobroma cacao L.) is a significant agricultural commodity in the Dominican Republic, which ranks 11th in the world for cacao exports. To estimate genetic diversity, determine genetic identity, and identify any labeling errors, 14 SSR markers were employed to fingerprint 955 trees among cacao germplasm accessions and local farmer selections (LFS). Comparisons of homonymous plants across plots revealed a significant misidentification rate estimated to be 40.9 % for germplasm accessions and 17.4 % for LFS. The 14 SSRs amplified a total of 117 alleles with a mean allelic richness of 8.36 alleles per locus and average polymorphism information content (PIC) value of 0.67 for the germplasm collection. Similar levels of variation were detected among the LFS where a total of 113 alleles were amplified with a mean of 8.07 alleles per locus and PIC of 0.57. The observed heterozygosity (H_obs) was 0.67 for the germplasm collection and 0.60 for LFS. Based on population structure analysis 43.9 % of the germplasm accessions and 72.1 % of the LFS are predominantly of the Amelonado ancestry. Among these Amelonado, 51.7 % for the germplasm collection and 50.6 % for LFS corresponded to Trinitario hybrid lineage. Criollo ancestry was found in 7.6 and 9.5 % of the germplasm accessions and LFS, respectively. The Contamana, Nacional, and Iquitos backgrounds were also observed in both populations, but the Curaray background was only detected in the germplasm accessions. No Purús or Guiana ancestry was found in either of the populations. Overall, significant genetic diversity, which could be exploited in the Dominican Republic breeding and selection programs, was identified among the germplasm accessions and LFS.     

Reliability evaluation of sampling plan fixed by Council Directive 91/68/EEC for the maintenance of officially brucellosis-free flock status

The European Union (EU) strategy with respect to sheep and goat brucellosis aims to eradicate the infection and achieve officially brucellosis-free (OBF) status in all EU holdings and territories. Council Directive 91/68/EEC of 28 January 1991 states that to maintain OBF status of ovine or caprine holdings located outside an OBF territory, only a representative number of animals need to be tested annually. However, depending on the number of animals in a holding, this testing method risks non-detection of the infection, thereby reducing the efficacy of the brucellosis control plan. The recommended sampling procedure has a low sensitivity for detecting infection in medium-sized flocks; furthermore, the risk of not detecting re-infection in OBF flocks, particularly in territories that have not yet gained OBF status, is also not acceptable. Moreover, in large-sized flocks, the Directive sampling procedure entails taking an excessive number of samples, which can be very expensive. The authors evaluated, by using statistical analyses and a simulation model based on field data, the possible consequences of the current EU strategy. It is suggested that the sampling criteria for the maintenance of OBF status in the EU should be modified and that a statistically based sampling method should be applied instead of the fixed percentage method that is currently in use.     

Genetic parameters for milk fatty acids,milk yield and quality traits of a Holstein cattle population reared under tropical conditions

Information about genetic parameters is essential for selection decisions and genetic evaluation. These estimates are population specific; however, there are few studies with dairy cattle populations reared under tropical and sub‐tropical conditions. Thus, the aim was to obtain estimates of heritability and genetic correlations for milk yield and quality traits using pedigree and genomic information from a Holstein population maintained in a tropical environment. Phenotypic records (n = 36 457) of 4203 cows as well as the genotypes for 57 368 single nucleotide polymorphisms from 755 of these cows were used. Covariance components were estimated using the restricted maximum likelihood method under a mixed animal model, considering a pedigree‐based relationship matrix or a combined pedigree‐genomic matrix. High heritabilities (around 0.30) were estimated for lactose and protein content in milk whereas moderate values (between 0.19 and 0.26) were obtained for percentages of fat, saturated fatty acids and palmitic acid in milk. Genetic correlations ranging from −0.38 to −0.13 were determined between milk yield and composition traits. The smaller estimates compared to other similar studies can be due to poor environmental conditions, which may reduce genetic variability. These results highlight the importance in using genetic parameters estimated in the population under evaluation for selection decisions.