Field evaluation of treatments for the control of the bacterial apical necrosis of mango (Mangifera indica) caused by Pseudomonas syringae pv. syringae

Bacterial apical necrosis is a critical disease in the main production area of mango in Europe. It is caused by Pseudomonas syringae pv. syringae, and produces necrotic lesions on mango buds and leaves, causing severe yield losses due to a decrease of flowering and fruit set. A field study to evaluate control treatments against bacterial apical necrosis was carried out during three seasons on mango trees cv. Tommy Atkins in Huelva (Spain). Experimental treatments included Bordeaux mixture, fosetyl-Al, acibenzolar-s-methyl, gibberelic acid, silicon gel, a mixture between acibenzolar-S-methyl and Bordeaux mixture, and combined applications of fosetyl-Al with Bordeaux mixture or silicon gel. The treatments which caused a consistent reduction in bacterial apical necrosis symptoms at similar levels to the conventional treatment with Bordeaux mixture, were the plant resistance activator acibenzolar-S-methyl and the phosphonate derivative fosetyl-Al applied singly or in combination with other compounds, which could be alternative treatments. These treatments showed a significant decrease in the necrotic buds and/or leaves numbers; however, minor differences in P. syringae-like population levels were observed. The analysis of the inhibitory and bactericidal concentrations of cupric compounds against P. syringae strains isolated from mango tissues suggests that the commercial copper-based treatments with Bordeaux mixture used in the management of mango crops do not work in a bactericidal mode of action.     

Consequences of Landscape Heterogeneity on Grassland Diversity and Productivity in the Espinal Agroforestry System of Central Chile

The current land use system in the anthropogenic savannas (Espinales) of the Mediterranean climate region of Chile, has resulted in considerable heterogeneity at the landscape level which is associated with different covers of the legume tree, Acacia caven. The effects of landscape heterogeneity on the diversity and productivity of herbaceous plant communities were studied in 29 plots of 1000 m², with a wide range of woody cover. A detrended correspondence analysis of the species × plots matrix explained 73% of the total variation and revealed the existence of two trends of variation in floristic composition: one associated with physiographic position (hillsides and flatlands) and the other related to the number of years since the last cutting, or coppicing, of A. caven. Despite the great majority of the original herbaceous species having disappeared as a result of the prevailing land use system, some native species have been able to survive especially on hillside areas with low grazing intensity. Woody cover was a good indicator of spatial heterogeneity and land use history. It was also correlated with stocking rate, above-ground biomass of herbaceous vegetation, and soil fertility (organic matter, nitrogen and phosphorus concentration), both on hillsides and flatlands. The relationship between woody cover and herbaceous plant species richness was significant and unimodal in flat land areas, and linear, and marginally significant, on hillsides. The consequences of land use changes on the conservation of the ecological and productive values of grasslands are analyzed.     

Oxidative stress regulates the expression of the Pht cluster genes involved in phaseolotoxin synthesis in <Emphasis Type="Italic">Pseudomonas syringae</Emphasis> pv. <Emphasis Type="Italic">phaseolicola</Emphasis> NPS3121

This study evaluated the role of oxidative stress on the expression of Pht cluster genes involved in phaseolotoxin synthesis in Pseudomonas syringae pv. phaseolicola. Results demonstrate that the expression of Pht cluster genes is regulated by oxidative stress in a manner dependent of the ROS present in the cell. The presence of H₂O₂ and Paraquat, influences on the expression of the Pht cluster genes in function of the compound and of the concentration evaluated, demonstrating that expression of Pht genes is part of the oxidative stress response in P. syringae pv. phaseolicola NPS3121.     

Genetic parameters for growth and survival traits in Pacific white shrimp Penaeus (Litopenaeus) vannamei from a nucleus population undergoing a two-stage selection program

A multivariate animal model and multi-generational data from a two-stage selection shrimp breeding program were used to estimate genetic parameters for a genetic nucleus of Penaeus (Litopenaeus) vannamei. A total of 408,648 records from years 2008 to 2010 production cycles provided by a Mexican hatchery were analyzed. The studied traits were survival from 0 to 28 days of age (S1), square root of body weight at 28 days of age (W1^1/2), survival from 65 to 130 days of age (S2), and body weight at 130 days of age (W2). Mean (standard deviation) for W1^1/2 and W2 were estimated as 5.4 mg^1/2 (1.55) and 13.6 g (3.1), respectively, while mean (standard deviation) for S1 and S2 (as proportions) were estimated as 0.20 (0.41) and 0.71 (0.45), respectively. Heritabilities for S1, W1^1/2, S2, and W2 were 0.03 ± 0.01, 0.13 ± 0.03, 0.04 ± 0.01, and 0.21 ± 0.04, respectively. Genetic correlations of S1 with W1^1/2, S2, and W2 were ?0.49 ± 0.21, ?0.29 ± 0. 21, and ?0.40 ± 0.16, respectively. Genetic correlations of W1^1/2 with S2, and W2 were 0.55 ± 0.17, and 0.71 ± 0.12, respectively, and genetic correlation between S2 and W2 was 0.56 ± 0.10. Results show that selection based on W2 has a positive effect on S2, while selection based on W1^1/2, as an early selection criterion, would increase the selection responses for W2 and S2.     

Embryonic development and influence of egg density on early veliger larvae and effects of dietary microalgae on growth of brown mussel Perna perna (L. 1758) larvae under laboratory conditions

The effect of egg density on embryonic development and larval quality as well as the lipid and fatty acid contents (eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA) of cultured microalgae fed to Perna perna larvae was studied under controlled conditions to provide information needed for development of an experimental hatchery. Embryonic development followed the common sequence exhibited by other bivalves. d-larva stage was attained 40–44 h post-fertilisation at 21 ± 1 °C. The umbo-stage was reached in 11 days, and pediveliger larvae were observed 26 days post-fertilisation. Low egg density (range 20–100 eggs cm^?2) produced high proportions of normal d-larvae. Larval development showed two growth phases: 1st—the mixotrophic stage and 2nd—the exotrophic stage where the composition of diets had significant effects on larval growth with higher rates in larvae fed with the mixed microalgae (Isochrysis galbana + Chaetoceros calcitrans, I. galbana + Phaeodactylum tricornutum and I. galbana + Skeletonema costatum) in comparison with the monospecific diet (I. galbana). Fatty acid analysis showed that larval growth and survival were strongly influenced by proportions of dietary DHA and EPA. These results indicate that DHA and EPA are the key factors in determining larval performance, considerably more than the total amount of other fatty acids.     

Chlorogenic acid protects paraoxonase 1 activity in high density lipoprotein from inactivation caused by physiological concentrations of hypochlorite

We hypothesized that chlorogenic acids, the main phenolics in coffee, many fruits and Ilex paraguariensis extracts, protect paraoxonase 1 activity in HDL from inactivation by chlorination at concentrations of HOCl (50 μM) and chlorogenic acid (2–10 μM) compatible with those found in humans.