RNAi as an emerging approach to control Fusarium head blight disease and mycotoxin contamination in cereals

Fusarium graminearum is a major fungal pathogen of cereals worldwide, causing seedling, stem base and floral diseases, including Fusarium head blight (FHB). In addition to yield and quality losses, FHB contaminates cereal grain with mycotoxins, including deoxynivalenol, which are harmful to human, animal and ecosystem health. Currently, FHB control is only partially effective due to several intractable problems. RNA interference (RNAi) is a natural mechanism that regulates gene expression. RNAi has been exploited in the development of new genomic tools that allow the targeted silencing of genes of interest in many eukaryotes. Host‐induced gene silencing (HIGS) is a transgenic technology used to silence fungal genes in planta during attempted infection and thereby reduces disease levels. HIGS relies on the host plant's ability to produce mobile small interfering RNA molecules, generated from long double‐stranded RNA, which are complementary to targeted fungal genes. These molecules are transferred from the plant to invading fungi via an uncharacterised mechanism, to cause gene silencing. Here, we describe recent advances in RNAi‐mediated control of plant pathogenic fungi, highlighting the key advantages and disadvantages. We then discuss the developments and implications of combining HIGS with other methods of disease control. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Soil Enzymatic Activity in Eucalyptus Grandis Plantations of Different Ages

Eucalyptus plantations have become increasingly common in Latin America. However, because Eucalyptus is an exotic species, its presence has raised concerns about changes in the environment, especially to soil properties. The objective of this study was to investigate possible changes in selected soil enzyme activity after several years of Eucalyptus cultivation. Soil samples were collected from four locations: a native forest (Atlantic Forest) used as a reference for the original soil conditions and three E. grandis plantations aged 2, 3 and 5 years, established in 2008, 2007 and 2005, respectively. The native vegetation had been removed and the soil graded and ploughed to establish these plantations. We evaluated soil enzymatic activities (β‐glucosidase, acid phosphatase, dehydrogenase, urease and arylsulfatase) at each location. The activity of β‐glucosidase, phosphatase, dehydrogenase and urease was improved after 5 years, whereas arylsulphatase was impacted negatively. The multivariate analysis showed that the majority of enzyme activities reached the values observed in native forest after the third year of reforestation. The activity of β‐glucosidase was crucial in differentiating the area with 2 years of reforestation from the native forest. The removal of native vegetation in order to establish commercial plantations raises concerns about the real impacts of this practice on the soil. In the present study, plantations of Eucalyptus improved most of the selected enzyme activities after the third year of reforestation. Copyright © 2015 John Wiley & Sons, Ltd.     

Comparative evaluation of experimental challenge by intraperitoneal injection and cohabitation of Atlantic salmon (Salmo salar L) after vaccination against Piscirickettsia salmonis (EM90‐like)

The Chilean aquaculture has been challenged for years by piscirickettsiosis. A common prophylactic measurement to try to reduce the impact from this disease is vaccination, but the development of vaccines that induce satisfactory protection of the fish in the field has so far not been successful. Experimental challenge models are used to test vaccine efficacy. The aim of this study was to evaluate the performance of experimental vaccines after challenge by the two most widely used challenge routes, intraperitoneal injection and cohabitation. A total of 1,120 Atlantic salmon were vaccinated with non‐commercial experimental vaccines with increasing amounts of an inactivated Piscirickettsia salmonis EM90‐like isolate. Differences in mortality, macroscopic and microscopic pathological changes, bacterial load and immune gene expression were compared after challenge by different routes. The results revealed a similar progression of the diseases after challenge by both routes and no gross differences reflecting the efficacy of the vaccines could be identified. The analysis of the immune genes suggests a possible suppression of the cellular immunity by CD8 T cell and with this stimulation of bacterial survival and replication. Comparative studies of experimental challenge models are valuable with regard to identifying the best model to mimic real‐life conditions and vaccines’ performance.     

Evaluating unoccupied aerial systems (UAS) imagery as an alternative tool towards cotton-based management zones

Unoccupied aerial system (UAS) imagery may serve as an additional tool towards management zone delineation. This is because UAS data collection is relatively flexible. However, it is unclear how useful UASs can be towards generating management zones, relative to preexisting tools (e.g. apparent soil electrical conductivity or EC_a). The purpose of this study, therefore, was to evaluate UAS imagery, relative to EC_a, in terms of their ability to: 1) predict cotton traits (i.e. height, seed cotton yield), and 2) define cotton management zones based on these traits. Single-season UAS images from multispectral/thermal sensors were collected and processed into Normalized Difference Vegetation Index (NDVI) and radiometric surface temperature (T_r), respectively. Management zones were also delineated using digital camera (RGB) imagery collected at periods before planting and near harvest. RGB management zones were delineated by a novel open boll mapping approach. In-season NDVI and T_r layers were significant (P?<?0.01) predictors of canopy height. Additionally, NDVI and T_r maps produced statistically different management zones during flowering and boll filling growth stages in terms of yield (P?=?0.001 or less). Open boll layers were all more accurate predictors of cotton seed yield than EC_a data—these two layers also produced statistically distinct management zones. ANOVA tests revealed that, given EC_a alone, adding UAS information via the RGB open boll map resulted in a significantly different yield prediction model (P?<?0.001). These results suggest that UAS imagery can offer valuable information for cotton management zone delineation that other techniques cannot.

     

Cassava starch factory residues in the diet of slow-growing broilers

The objective of this study was to evaluate the effect of inclusion of dehydrated cassava starch residue (DCSR) on the performance, gastrointestinal tract characteristics and carcass traits of ISA Label JA57 slow-growing broilers. A total of 510 broilers at 21 were distributed in a randomized experimental design with 5 treatments (2, 4, 6, 8, and 10 % DCSR inclusion) and a control group, 5 replicates, and 17 birds per experimental unit. The DCSR inclusion from 21 to 49 days of age negatively influenced (P?P?>?0.05) feed conversion in the broilers with increasing of DCSR inclusion. From 21 to 79 days, DCSR inclusion impaired (P?P?P?P?>?0.05) the other parameters of carcass quality and yield, cuts, and percentage of abdominal fat. In conclusion, DCSR inclusion levels above 2 % compromised broiler performance.     

Agronomic and molecular characterization of gamma ray induced banana (<Emphasis Type="Italic">Musa</Emphasis> sp.) mutants using a multivariate statistical algorithm

Bananas are tropical fruits grown worldwide playing a key role in market trade and especially used as main food source for low income populations. In Brazil, bananas are mainly consumed in natura, occupying the second largest internal market. Nevertheless, this crop presents low availability of productive commercial varieties with good agronomic characteristics. A strategy undertaken to solve this problem is the development of new cultivars through conventional genetic breeding methods. However, this strategy presents some obstacles such as female sterility and low number of seeds. In order to overcome these shortcomings, use of mutation induction aiming the selection of mutants with desirable agronomic characteristics seems to have great potential for developing new cultivars. The objective of the present work was to evaluate the genetic variability in putative banana ‘Pacovan’ (AAB genome, subgroup Prata Type) mutants submitted to gamma ray irradiation, using a set of agronomical and molecular data (ISSR markers). The distance between the putative ‘Pacovan’ mutants varied from 0.26 to 0.64 with cophenetic correlation coefficient of 0.7669. Four mutants were selected based on best agronomical characteristics and height. This data also shows that there is variability that can be explored after the irradiation of ‘Pacovan’ banana mutants, which can be used in the genetic breeding program of banana aiming to develop short new varieties that also present good agronomic characteristics. This is the first attempt to use combined data in order to evaluate the genetic variability in putative banana mutants.     

Antinecrotic and Antiapoptotic Effects of Different Concentrations of Copaiferalangsdorffii Essential Oil in Macrophages and Lymphocytes of Mice

Purpose： to evaluate the in vitro influence of Copaiferalangsdorffii essential oil on the antinecrotic activity in macrophages, and on the antiapoptotic activity in macrophages and lymphocytes of Swiss mice. Methods： lymphocytes and macrophages were obtained from ten 60-day-old male mice weighing 42-45 g, and then cultured in 24-well plates. Cells were treated with concentrations of 2%, 5%, 10% and 20% of oil from Copaiferalangsdorffii before or after induction of apoptosis with ultraviolet light. We used positive and negative controls. Hoechst staining was performed, and then images of cells under fluorescence microscope were captured and digitalized. We used Image J_1.46o to quantify the fluorescence intensity/brightness of condensation of the chromatin ofapoptotic cells. We used one-way ANOVA with Bonferroni＇s and Tukey＇s multiple comparison tests. Results are expressed as the means of relative densities after adjustment and 95% confidence intervals; P 〈 0.05 was considered statistically significant. Results： oil from Copaiferalangsdorffii at different concentrations has decreased necrosis and apoptosis of both lymphocytes and macrophages from mice, when compared to C＋ （all P 〈 0.05）. Discussion： Copaiferalangsdorffii is typically Brazilian and found in the Amazon region, with anti-inflammatory, antioxidant and antineoplastic effects due to its oil compounds, such as xyloglucans and kaurenoic acid. Its potential therapeutical usage was demonstrated in a national study. The present study showed that its oil has significant in vitro antiapoptotic and antinecrotic activity and it should be tested experimentally in vivo.