A disease and production index (DPI) for selection of cacao (Theobroma cacao) clones highly productive and tolerant to pod rot diseases

Frosty pod rot (FPR) (Moniliophthora roreri), along with black pod rot (Phytophthora species) and witches’ broom disease (Moniliophthora perniciosa) constitute the main phytosanitary problems limiting cacao (Theobroma cacao) production causing severe yield losses. One of the main sought after methods of pod rot management is the selection of tolerant cacao genotypes. Typically, the selection is carried out through the quantification of the percentage of diseased pods (PDP). However, PDP does not consider the relative productivity, or production potential (PT) of the genotype. Production potential can vary among cacao genotypes. Consequently, genotypes with similar PT can have similar or vastly different disease tolerance levels as measured by PDP. The disease and production index (DPI) was developed to integrate a genotype's tolerance to M. roreri and other diseases as measured by PDP, with its PT. Here, we evaluated the number of healthy pods, number of diseased pods, and weight of fresh seed for 29 clones grown in replicated five-tree plots over 4 years. The data obtained was used to calculate PDP and DPI for each clone for three different disease combinations: frosty pod rot alone, pod rots other than frosty pod rot, and the combination of all pod rots. Multivariate analysis verified that DPI discriminated between clones based on productivity and disease tolerance. Surprisingly, there was a close ranking of clones between resistance to FPR and resistance to all other pod rots. The DPI can be used in breeding programmes focused on the selection of high yielding disease-tolerant cacao genotypes.     

A new resistance gene to PepYMV (Pepper yellow mosaic virus) in Capsicum annuum L.

Pvr4 locus, commonly associated with a co-dominant CAPS marker, confers monogenic dominant resistance to potyvirus complex in Capsicum spp. Aiming to investigate whether the resistance found in resistant genotypes not bearing Pvr4 marker is due to allelism in the Pvr4 locus, or due to a new locus of the pvr series, segregation analyses of an F₂ population obtained from a cross between two pepper lines “Myr-29-10” (P₁) (resistant to PepYMV, showing a single band of 444 bp, Pvr4/Pvr4) and “PIM-025” (P₂) (resistant to PepYMV, showing a single band of 458 bp, Pvr4⁺/Pvr4⁺) were performed. According to the results, there is strong evidence that the locus controlling PepYMV resistance in PIM-025 (P₂) is not Pvr4. These results provide evidence that those resistant genotypes, bearing a susceptible band pattern in the Pvr4 locus (458 bp, Pvr4⁺/Pvr4⁺), carry a different gene from those described in the literature up to the present time.     

Using public databases for genomic prediction of tropical maize lines

In this paper, the aims were (a) to test the usefulness of using genomic and phenotypic information from public databases (open access) to predict genetic values for tropical maize inbred lines regarding plant and ear height; (b) to identify how the population structure, the use of optimized training sets (OTSs) and the amount of information originating from public databases affect the predictive ability. Thus, 29 training sets (TSs) were defined considering three diversity panels: the University of São Paulo (USP—validation set (VS)) and the ASSO and USDA North Central Regional Plant Introduction Station (NCRPIS) (external public panels—predictors), which were divided into four scenarios with different TS configurations. We showed that it is possible to use public datasets as a primary TS and that population structure can modify the predictive abilities of GS. In the four scenarios proposed, very large or very small sets did not provide predictive abilities over 0.53 for GS. However, OTSs composed of 250 individuals were sufficient to achieve predictive abilities over this limit.     

Fractionation of soil phosphorus in organic amended farms located on savanna sandy soils of Venezuelan Amazonian

In Venezuelan Amazonian, some producers have established small agroforestry systems of production on sandy savanna soils by a long-term addition (more than 25 years) of animal manures at a low dressing (2 Mg ha⁻¹) as fertilizer input. As a result of the organic fertilizers regime, the original savanna soil has been changed in terms of soil quality parameters. The main objective of the study was to investigate using sequential fractionation of soil P the impact of organic manures on the amount and partitioning of bioavailable P in soils of the Amazonas. Fractionation was carried out on Typic Ustipsamments amended with three different organic manure sources for extended periods. In general, after fertilization, all Pi and Po fractions increased significantly. The increase was striking in the resin-Pi and HCl-Pi, and among the organic P fractions, the changes were highest for the NaOH-Po sonicated and non-sonicated fractions. The total P increment was more relevant when soils were amended with chicken manure (1,194 mg Pt kg⁻¹) and less relevant for the farm soil treated with compost (500 mg Pt kg⁻¹), where the soil amended with cattle waste presented an intermediate value in total soil P (851 mg Pt kg⁻¹). The importance of this field study was to assess the sustainability of long-term established organic management characterized by the low inputs, and this information is poor in the Amazonas.     

Impacts of anthropic pressures on soil phosphorus availability,concentration, and phosphorus forms in sediments in a Southern Brazilian watershed

Purpose  

The transfer of soil sediments and phosphorus from terrestrial to aquatic systems is a common process in agricultural lands. The aims of this paper are to quantify the soil phosphorus availability and to characterize phosphorus forms in soil sediments as contaminant agents of waters as a function of anthropic pressures.     

Identification of parasites in Puffinus puffinus (Birds, Procellariiformes) from Northeastern Brazil

Studies on the parasitic fauna of migratory sea birds of the Puffinus genus are scarce. Therefore, the aim of this study was to identify parasites of 16 specimens of Puffinus puffinus (Procellariiformes, Procellariidae) that died during the period of June 2011 to December 2011 at the Wildlife Screening Center (CETAS) of the Brazilian Institute of Environment and Natural Resources (IBAMA) in Cabedelo, Paraíba. During necropsy, biting lice and/or gastrointestinal helminths were collected in seven (43.7?%) birds. Lice were collected in five (31.2?%) birds, and the species identified were Halipeurus diversus, Trabeculus aviator, Austromenopon paululum), Saemundssonia sp. and Naubates sp. The prevalence of helminths was also 31.2?%. The nematodes species were Seuratia shipleyi and Contracaecum sp., and cestodes were Tetrabothrius sp. This is the first record in Brazil of Naubates sp., Seuratia shipleyi, Contracaecum sp., and Tetrabothrius sp. in Puffinus puffinus.     

Using binary and probabilistic habitat availability indices derived from graph theory to model bird occurrence in fragmented forests

Loss of connectivity is one of the main causes of decreases in habitat availability and, thus, in species abundance and occurrence in fragmented landscapes. It is therefore important to measure habitat connectivity for conservation purposes, but there are several difficulties in quantifying connectivity, including the need for species movement behavioral data and the existence of few consistent indices to describe such data. In the present study, we used a graph theoretical framework to measure habitat availability, and we evaluate whether this variable is adequate to explain the occurrence pattern of an Atlantic rainforest bird (Pyriglena leucoptera, Thamnophilidae). The playback technique was used to parameterize the connectivity component of habitat availability indices and to determine the presence or absence of the study species in forest patches. Patch- and landscape-level habitat availability indices were considered as explanatory variables. Two of these were landscape-level indices, which varied in terms of how inter-patch connections are defined, using either a binary or probabilistic approach. This study produced four striking results. First, even short open gaps may disrupt habitat continuity for P. leucoptera. Second, the occurrence of P. leucoptera was positively affected by habitat availability. Third, proper measures of this explanatory variable should account for the landscape context around the focal patch, emphasizing the importance of habitat connectivity. Finally, habitat availability indices should consider probabilistic and not binary inter-patch connections when intending to explain the occurrence of bird species in fragmented landscapes. We discuss some conservation implications of our results, stressing the advantages of an ecologically scaled graph theoretical framework.     

Membrane toxicity of antimicrobial compounds from essential oils

Natural antimicrobial compounds perform their action mainly against cell membranes. The aim of this work was to evaluate the interaction, meant as a mechanism of action, of essential oil antimicrobial compounds with the microbial cell envelope. The lipid profiles of Escherichia coli O157:H7, Staphylococcus aureus, Salmonella enterica serovar Typhimurium, Pseudomonas fluorescens, and Brochothrix thermosphacta cells treated with thymol, carvacrol, limonene, eugenol, and cinnamaldehyde have been analyzed by gas chromatography. In line with the fatty acids analysis, the treated cells were also observed by scanning electron microscopy (SEM) to evaluate structural alterations. The overall results showed a strong decrease of the unsaturated fatty acids (UFAs) for the treated cells; in particular, the C18:2trans and C18:3cis underwent a notable reduction contributing to the total UFA decreases, while the saturated fatty acid C17:0 raised the highest concentration in cinnamaldehyde-treated cells. SEM images showed that the used antimicrobial compounds quickly exerted their antimicrobial activities, determining structural alterations of the cell envelope.     

Copper(II) catalysis in cyanide conversion into ethyl carbamate in spirits and relevant reactions.

The role of copper(II) species in the oxidation of inorganic cyanide to cyanate and in the conversion of cyanate or urea into ethyl carbamate was investigated. The oxidation process has been shown to be independent from the dissolved oxygen. Elemental analysis and infrared spectroscopy have shown the formation of a mixed copper carbonate/hydroxide in the process of oxidation of cyanide to cyanate in water/ethanol. The complexation to Cu(II) of cyanate formed upon cyanide oxidation makes the former more susceptible to nucleophilic attack from ethanol, with conversion into ethyl carbamate. Comparatively, urea has a minor role with respect to cyanide in the formation of ethyl carbamate. Therefore, the urea present in some samples of Brazilian sugar cane spirit (cacha?a) has been shown to have almost no influence on the ethyl carbamate content of cacha?as, which comes essentially from cyanide. Fe(II,III) affords results similar to those found with Cu(II). Some suggestions are presented to avoid ethyl carbamate formation in spirits during distillation.