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Summary

Enhancement of the resistance level in plants by rhizobacteria has been proven in several pathosystems. This study investigated the ability of four rhizobacteria strains (Pseudomonas putida BTP1 and Bacillus subtilis Bs2500, Bs2504 and Bs2508) to promote the growth in three barley genotypes and protect them against Cochliobolus sativus. Our results demonstrated that all tested rhizobacteria strains had a protective effect on barley genotypes Arabi Abiad, Banteng and WI2291. However, P. putida BTP1 and B. subtilis Bs2508 strains were the most effective as they reduced disease incidence by 53 and 38% (mean effect), respectively. On the other hand, there were significant differences among the rhizobacteria-treated genotypes on plant growth parameters, such as wet weight, dry weight, plant height and number of leaves. Pseudomonas putida BTP1 strain was the most effective as it significantly increased plant growth by 15-32%. In addition, the susceptible genotypes Arabi Abiad and WI2291 were the most responsive to rhizobacteria. This means that these genotypes have a high potential for increase of their resistance against the pathogen and enhancement of plant growth after the application of rhizobacteria. Consequently, barley seed treatment with the tested rhizobacteria could be considered as an effective biocontrol method against C. sativus.

Summary

This study aims to develop a biocontrol agent against Fusarium oxysporum f.sp. radicis-lycopersici (FORL) in tomato. For this, a set of 23 bacterial endophytic isolates has been screened for their ability to inhibit in vitro the growth of FORL using the dual plate assay. Three isolates with the most sound antagonistic activity to FORL have been qualitatively screened for siderophore production, phosphates solubilization and indolic acetic acid (IAA) synthesis as growth promotion traits. Antagonistic values of the three candidates against FORL were respectively: 51.51 % (EB4B), 51.18 % (EB22K) and 41.40 % (EB2A). Based on 16S rRNA gene sequence analysis, the isolates EB4B and EB22K were closely related to Enterobacter ludwigii EN-119, while the strain EB2A has been assigned to Leclercia adecarboxylata NBRC 102595. The promotion of tomato growth has been assessed in vitro using the strains EB2A, EB4B and EB22K in presence of the phytopathogen FORL. The treatments with the selected isolates increased significantly the root length and dry weight. Best results were observed in isolate EB4B in terms of growth promotion in the absence of FORL, improving 326.60 % of the root length and 142.70 % of plant dry weight if compared with untreated controls. In the presence of FORL, the strain EB4B improved both root length (180.81 %) and plant dry weight (202.15 %). These results encourage further characterization of the observed beneficial effect of Enterobacter sp. EB4B for a possible use as biofertilizer and biocontrol agent against FORL.

Summary

The olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) is the major pest of olives worldwide. The figitid wasp, Aganaspis daci (Hymenoptera: Figitidae), is a larval-prepupal endoparasitoid of fruit fly species, and it was found to successfully parasitize medfly larvae in field-infested figs in Greece. To assess the potential of A. daci as a biological control agent against B. oleae, we studied the effect of olive fruit size on parasitism rates of A. daci on 2nd and 3rd instar larvae of B. oleae, by using fruit of different size (cultivar ‘Chalkidikis’) and wild olive fruit. In addition, we conducted releases of A. daci females in a pilot olive grove in Volos, Magnesia. From July to October, we released 200 A. daci females/0.1 ha/week, followed by olive fruit sampling to estimate olive fruit infestation levels and the parasitism rates of A. daci. Laboratory trials revealed that fruit size and larvae instar were predictors of parasitism success of A. daci, with parasitism rates higher for small-size fruit of the cultivar “Chalkidikis” and the 3rd instar larvae of B. oleae. In field trials, no A. daci adults emerged from the olive fly infested fruit.

Summary

Root-knot nematodes (RKN), Meloidogyne spp., have a wide host range and are common in the Mediterranean area. Cultivated lavender (Lavandula angustifolia) was found naturally infested by M. hapla in Kozani area, the first documented infestation of this crop by RKN in Greece. Oxalis pescaprae, a common winter weed in Crete, was found to be a host of M. javanica under artificial inoculation. This weed acts as a potential winter host of the nematode in fields cultivated with vegetable crops. Two populations of M. ethiopica were found in kiwi and maize in Greece in the past. Recently, populations of M. ethiopica from Europe were re-classified as M. luci, based only on the population isolated from kiwi for Greece. In the current work, the RKN populations originating from kiwi and maize and maintained on tomato, were identified as M. luci. Nematode species identification was determined by electrophoretic analysis of protein extracts obtained from females.

Summary

Phenology and parasitism of the scale insect, Coccus pseudomagnoliarum (Kuwana) (Hemiptera: Coccomorpha: Coccidae), infesting Citrus sinensis (Rutaceae), were studied in Papagou area, in northeastern Athens, from June 2015 to June 2017. Coccus pseudomagnoliarum is a univoltine, viviparous, parthenogenetic species. It overwintered as settled 1st instar nymph on the shoots of the trees. The 2nd instar nymphs appeared between the beginning of April and the end of May, and the mature females were recorded from the beginning of May until the middle of June. The crawlers appeared between the middle of May and the middle of June and the 1st instar nymphs settled on the shoots at the end of May, where they remained during the whole summer period, winter, until the beginning of April next year. Parasitism of the scale was recorded between the beginning of May and the middle of May and reached a maximum rate of 35%. The recorded parasitoid species were Coccophagus shillongensis Hayat and Singh (Hymenoptera: Aphelinidae), Coccophagus spp. and Metaphycus dispar (Mercet) (Hymenoptera: Encyrtidae).

Abstract

Introduction

African swine fever (ASF) is a pressing economic problem in a number of Eastern European countries. It has also depleted the Chinese sow population by 50%. Managing the disease relies on culling infected pigs or hunting wild boars as sanitary zone creation. The constraints on the development of an efficient vaccine are mainly the virus’ mechanisms of host immune response evasion. The study aimed to adapt a field ASFV strain to established cell lines and to construct recombinant African swine fever virus (ASFV) strain.

Material and Methods

The host immune response modulation genes A238L, EP402R, and 9GL were deleted using the clustered regularly interspaced short palindromic repeats/caspase 9 (CRISPR/Cas9) mutagenesis system. A representative virus isolate (Pol18/28298/Out111) from Poland was isolated in porcine primary pulmonary alveolar macrophage (PPAM) cells. Adaptation of the virus to a few established cell lines was attempted. The plasmids encoding CRISPR/Cas9 genes along with gRNA complementary to the target sequences were designed, synthesised, and transfected into ASFV-infected PPAM cells.

Results

The reconstituted virus showed similar kinetics of replication in comparison to the parent virus isolate.

Conclusion

Taking into account the usefulness of the developed CRISPR/Cas9 system it has been shown that modification of the A238L, EP402R, and 9GL genes might occur with low frequency, resulting in difficulties in separation of various virus populations.

Abstract

The experiments reported in this research paper were aimed at assessing the genetic responses of a Holstein cow population, as a response to the variations in environmental temperature, through the analysis of the effects resulting from the genotype by environment interaction (GEI), based on reaction norms. Therefore, milk production data was collected from the database of the Paraná Holstein Breeders Association in Brazil for 67,360 primiparous cows born between 1990 and 2015, with the purpose of evaluating the temperature effect, considered as an environmental variable, distinguished under six gradients (17 ºC to 19.5 ºC) over the region. A random regression model was adopted, utilizing the fourth order under the Legendre polynomials, applying the mixed models of analysis by the REML method, and using the WOMBAT software. Additionally, the breeding value of the 15 most representative bulls was assessed, in response to the changes in the temperature gradient. The total milk production on average was estimated at 8,412.83 ± 2,012.08 kg. The heritabilities estimates were found in the low to moderate range, from 0.18 to 0.23, displaying a decline with a rise in the temperature, highlighting the influence it exerted on the heritabilities. Variations in the genetic expression of some bulls were noted to show differences of up to 289 kg of milk in response to the increase in the temperature from 17 ºC to 19.5 ºC. However, all the genetic correlations between the gradients for milk yield were above 0.80, in the range of 0.873 to 0.998, revealing no remarkable interaction between the genotype and environment. This result indicates that the application of the temperature variable in the models of genetic analysis in southern Brazil is not required.

Abstract

The aim of this study was to determine the effect of Virginia fanpetals (Sida hermaphrodita) silage on carcass and beef quality characteristics. Forty Polish Holstein-Friesian bulls aged 16 months were assigned to 4 dietary treatments (n=10) and were fed different types of silage during a 7-month fattening period. The proportion (g/kg dry matter) of silage in the diets was as follows: (1) grass silage (GS) (600); (2) Sida silage (SS) (600); (3) SS (300) and GS (300); and (4) SS (300) and maize silage (MS) (300). Silage was supplemented with concentrate at 400 g/kg DM in each diet. The animals were slaughtered at the end of the fattening period. Silage type had no significant effect on BWG or feed to gain ratio. The carcasses of bulls fed Sida silage and maize silage received higher scores for conformation than the carcasses of bulls fed grass silage (P<0.05). The meat of bulls fed Sida silage had the lowest value of Warner-Bratzler shear force. Meat from SS+MS group bulls had the highest intramuscular fat (IMF) content and was lightest in color, whereas meat from bulls fed Sida silage and grass silage received the highest scores for color uniformity, aroma, taste and overall acceptability.

Abstract

Recent studies have demonstrated a significant role of mitochondrial DNA (mtDNA) defects in the pathogenesis of many human and some canine tumours. The aim of this study was to identify mutations in the ND2 and ND4 mitochondrial genes in canine mast cell tumours and determine their association with the process of neoplastic transformation and the phenotypic traits of dogs. In total, 136 gene sequences from 68 biological samples, including blood and neoplastic tissue samples from 34 dogs with diagnosed MCTs, were analysed. The study consisted in DNA sequencing of the ND2 and ND4 genes as well as bioinformatics and statistical analyses. For the first time, mutations in NADH-dehydrogenase genes were detected in dogs with MCTs. In total, 22 polymorphic loci and 19 mutations in the ND2 and ND4 genes were identified. The majority of the identified mutations were homoplasmic, and tumour heteroplasmy was detected in eight nucleotide positions in three dogs. Seven of the ND2 mutations and two of the ND4 mutations caused an amino acid change. The changes in non-synonymous protein-coding SNPs did not exert an adverse effect on proteins. A statistically significant correlation of the presence of mutations/polymorphisms with the sex, age, and size of the dogs and the tumour location was demonstrated. Polymorphisms and mutations in NADH-dehydrogenase genes, including mastocyte-specific changes, in canine mast cell tumours that had not been reported earlier in the literature were identified. Some of these changes may imply that these are the hotspot mutations in canine mast cell tumours. It cannot be excluded that the molecular changes are directly associated with the development of mast cell tumours, and further investigations are needed to verify whether they can become molecular markers of MCTs in the future.

Abstract

The aim of the study was to determine the effect of the method of fragmentation of hybrid rye and maize grain on digestibility parameters for ruminants. Varying degrees of fragmentation – none (whole grains; WG), crushed (CG) or ground to pass through a 4.0 (GG4.0) or 1.5 mm (GG1.5) screen – were estimated by the in sacco nylon bag technique, in vitro true digestibility (IVTD), and the in vitro gas production (GP) technique. WG, CG, GG4.0 and GG1.5 were categorized as none, slight, moderate and extensive fragmentation of the grain kernel, respectively. Three non-lactating cows fitted with ruminal and duodenal cannulas were used to determine the effective rumen degradability (ERD) and intestinal and total tract digestibility (ID and TTD, respectively) of dry matter (DM), crude protein (CP) and starch. IVTD was determined with an ANKOM DaisyII Incubator, and GP and in vitro organic matter digestibility were determined with an ANKOMRF Gas Production System. Dry matter, CP and starch of hybrid rye grain were rapidly degraded in the rumen, and this degradability as well as ID and TTD was only marginally affected by the method of kernel fragmentation; however, among the methods used, the ERD of GG4.0 rye was the lowest. On the other hand, the greater the degree of kernel fragmentation, the higher ERD, ID and TTD were obtained for the DM, CP and starch of maize grain. In summary, rye grain is more susceptible to fermentation in the rumen than maize grain, but the means of grain processing may alter the rate, extent and site of their digestion, particularly for maize grain.