Epidemiology,histopathology and aetiology of olive anthracnose caused by Colletotrichum acutatum and C. gloeosporioides in Portugal

Anthracnose is an important disease affecting mature olive fruits, causing significant yield losses, and poor fruit and oil quality. In Portugal, high anthracnose incidence was recorded during 2003–2007 with 41% of 908 orchards surveyed displaying disease symptoms. In another 14% of the orchards, the pathogen was recorded in symptomless plants. Disease severity was on average 36%, frequently reaching 100%. In Portugal, anthracnose is endemic to neglected orchards of susceptible cultivars, but under favourable conditions it can also severely affect less susceptible cultivars. Pathogens were genetically heterogeneous, with Colletotrichum acutatum genetic group A2 as the most frequent (80%), followed by group A4 (12%) and group A5 along with C. gloeosporioides (3–4%), while groups A3 and A6 of C. acutatum were sporadic. Important geographic variations were observed in the frequencies of these populations, accompanied by year‐to‐year populational shifts. Epidemiology and histopathology studies showed the presence of the pathogens on vegetative organs year‐round, particularly on olive leaves and branches, and on weeds. These represent inoculum reservoirs where secondary conidiation occurs, and conidia are then dispersed by spring rains reaching flowers and young fruits or by autumn rains reaching pre‐mature fruits. Unripe fruits were colonized without showing symptoms up to penetration of the cuticle, but further colonization and symptom production was completed only as fruits matured. These findings challenge current control practices, particularly the timing of fungicide treatment, and contribute to improved disease management.     

Diallel analysis of maize inbred lines for carotenoids and grain yield

Vitamin A deficiency causes xerophthalmia in preschool-aged children worldwide. The objective of this study was to estimate the genetic parameters that would be useful in selecting parent plants for developing productive hybrids with higher levels of provitamin A in the maize kernel. A complete 7 × 7 diallel mating scheme was used to generate 21 single-cross hybrids. The F₁ crosses and check hybrids were evaluated in complete block design across three different Brazilian environments, and carotenoid content was analyzed by high performance liquid chromatography. General combining ability effects were significant for all traits except α-carotene This result indicates that the contribution of the additive effect was more important for provitamin A and other carotenoids and, consequently that there is high chance of improving this trait through recurrent selection methods. Line 3 produced the highest level of kernel provitamin A among the inbred lines evaluated and also demonstrated the potential to contribute to the development of genetic materials with a good performance for provitamin A. Inbred lines 1, 6, and 7 showed a higher concentration of favorable alleles for grain yield, and inbred lines 3 and 6 exhibited a higher concentration of favorable alleles for β-carotene. Hybrid 1 × 3 performed well in terms of provitamin A and grain yield and combination 2 × 3 was the best performer in terms of lutein content.     

Characterization of genes <Emphasis Type="Italic">Rpp2</Emphasis>, <Emphasis Type="Italic">Rpp4</Emphasis>, and <Emphasis Type="Italic">Rpp5</Emphasis> for resistance to soybean rust

Asian rust, caused by the fungus Phakopsora pachyrhizi, is the most severe disease currently threatening soybean crops in Brazil. The development of resistant cultivars is a top priority. Genetic characterization of resistance genes is important for estimating the improvement when these genes are introduced into soybean plants and for planning breeding strategies against this disease. Here, we infected an F₂ population of 140 plants derived from a cross between ‘An-76’, a line carrying two resistance genes (Rpp2 and Rpp4), and ‘Kinoshita’, a cultivar carrying Rpp5, with a Brazilian rust population. We scored six characters of rust resistance (lesion color [LC], frequency of lesions having uredinia [%LU], number of uredinia per lesion [NoU], frequency of open uredinia [%OU], sporulation level [SL], and incubation period [IP]) to identify the genetic contributions of the three genes to these characters. Furthermore, we selected genotypes carrying these three loci in homozygosis by marker-assisted selection and evaluated their genetic effect in comparison with their ancestors, An-76, PI230970, PI459025, Kinoshita and BRS184. All three genes contributed to the phenotypes of these characters in F₂ population and when pyramided, they significantly contributed to increase the resistance in comparison to their ancestors. Rpp2, previously reported as being defeated by the same rust population, showed a large contribution to resistance, and its resistance allele seemed to be recessive. Rpp5 had the largest contribution among the three genes, especially to SL and NoU. Only Rpp5 showed a significant contribution to LC. No QTLs for IP were detected in the regions of the three genes. We consider that these genes could contribute differently to resistance to soybean rust, and that genetic background plays an important role in Rpp2 activity. All three loci together worked additively to increase resistance when they were pyramided in a single genotype indicating that the pyramiding strategy is one good breeding strategy to increase soybean rust resistance.     

Impact of glutathione on the formation of methylmethine- and carboxymethine-bridged (+)-catechin dimers in a model wine system

This study was performed to assess the impact of glutathione on the reaction between (+)-catechin and carbonyl compounds in wine-related conditions. (+)-Catechin (0.50 mM) and either glyoxylic acid (0.25 mM) or acetaldehyde (0.25 mM) were added to a model wine system with 0.0, 0.25, and 2.5 mM of glutathione added. UPLC-DAD and LC-MS analysis showed that the formation of carbonyl-bridged (+)-catechin dimers was inhibited in the samples with a glutathione to carbonyl ratio of 10:1 compared to the samples without glutathione. At a ratio of 1:1, glutathione inhibited the acetaldehyde-bridged dimers but only had a minor impact on the glyoxylic acid-bridged dimers. Further investigations showed that this trend of inhibition by glutathione on the glyoxylic acid-derived dimer was independent of temperatures, 20 °C vs 45 °C, or the presence of metal ions, 0.2 mg/L copper(II) and 5 mg/L iron(II). (1)H NMR analysis and LC-MS analysis provided evidence that glutathione inhibited dimer formation via different mechanisms depending on the carbonyl compound. For acetaldehyde-derived dimers, the main mode of inhibition was the ability of glutathione to form a (methyl-glutathionyl-methine)-(+)-catechin complex. Alternatively, the formation of a glutathione-glyoxylic acid addition product impeded the reaction between glyoxylic acid with (+)-catechin. These results demonstrate that glutathione, at sufficient concentration, can have a substantial impact on carbonyl-derived polymerization reactions in wine-like conditions.     

Microbiological Quality and Antibiotic Resistance Analysis of a Brazilian Water Supply Source

Water samples of the Passaúna River, Curitiba/Paraná (Brazil), were analyzed to determine total and thermotolerant coliform counts and Escherichia coli in order to provide information on human impacts on the water supply. Samples were collected and analyzed monthly, from March 2006 to February 2007, at five different locations along the river, and the multiple tube method was used to obtain total and thermotolerant coliform counts. The results varied from 130 MPN/100 mL to 1.6?×?10⁶ MPN/100 mL for total coliforms, while for thermotolerant coliforms the variation was between 40 MPN/100 mL and 5?×?10⁵ MPN/100 mL. The E. coli strains isolated from the samples were tested with 13 different antibiotics to determine their antibiotic resistance. The isolated strains were constantly sensitive to seven of the 13 antibiotics tested, and resistant to at least one of the other antibiotics. The results indicated that two factors could influence the increased contamination on this river, viz., seasonality parameters and domestic wastewater discharges. The determination of antibiotic resistance indices aimed to provide information on the anthropogenic influence. Only one of the locations investigated was considered critical due to the anthropogenic influence, with significant impacts from irregular domestic wastewater discharges.     

Genotoxic Effects in Erythrocytes of Oreochromis niloticus Exposed to Nanograms-per-Liter Concentration of 17??-Estradiol (E2): An Assessment Using Micronucleus Test and Comet Assay

Pharmacologically active substances used in the treatment of human and animal illnesses may usually enter the aquatic environment via effluents from sewage treatment plants, as they are not completely biodegraded or removed during waste water treatment. 17??-Estradiol genotoxicity was evaluated in Oreochromis niloticus (family Cichlidae) using micronucleus test, other nuclear abnormalities assessment, and the comet assay with erythrocytes. Fish were exposed to aqueous systems contaminated with 6 ng/L 17??-estradiol for three periods: 24 h, 48 h, and 10 days. The results showed that 17??-estradiol has genotoxic potential in different periods, since significant differences (P?=?0.036) were observed in the micronucleus frequencies of the 10-day exposure groups in relation to the control group. Also, the same was observed when comparing the nuclear abnormality frequencies (P?=?0.018) of the 24-h exposure group with the negative control group, and when using comet assay (P?<?0.001) for 48-h evaluations. The tested concentration of the 17??-estradiol gave rise to mutagenic and genotoxic effects on the blood cells of O. niloticus, therefore the substance being considered a clastogenic chemical contaminant on both acute and chronic exposures. The assessment using a combination of micronucleus test, nuclear abnormalities, and comet assays proved to be suitable and useful in the genotoxicity testing of 17??-estradiol at nanograms per liter.     

Antiradical properties of red wine portisins

The free radical chemistry of two polyphenolic pigments from red wine, belonging to the family of portisins, has been investigated after reaction with O(2)(?-) radicals using electron paramagnetic resonance (EPR) spectroscopy. Two portisins derived from malvidin-3-glucoside and cyanidin-3-glucoside were used for this study. Stable free radicals were detected with both portisins and correspond to unpaired electrons localized on the B as well as F rings of the portisins. Interpretations were confirmed by comparison with the spectra of free radicals formed by oxidation of the model compounds cyanidin-3-glucoside, malvidin-3-glucoside, and catechin. These results concur with previous work reporting the higher antiradical properties of these pigments compared to their anthocyanin precursors.