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Grapevine, one of the most important fruit crops worldwide is host to various pathogens, some of which have been spread intercontinentally in the early history of viticulture. One of the most problematic diseases is downy mildew, caused by the oomycete Plasmopara viticola (Berk. & Curt.) Berl. & de Toni which was introduced to Europe from North America in the 19th century. In addition to the establishment of chemical plant protection measures, extensive resistance breeding activities have succeeded in establishing varieties that are able to limit the propagation of this pathogen Recent studies have indicated an important role of subtilisin-like serine proteases (subtilases) in association with this increased disease tolerance. Gene expression analysis of two candidate subtilases was performed in seven cultivars with different levels of susceptibility to P. viticola. Two P. viticola isolates with different degrees of virulence were tested. Our results show that subtilases display different patterns of expression: Cucumisin exhibits peaks of expression, while VviSBT5.3a presents a bimodal behaviour. Nevertheless, both subtilases have a more pronounced response to the more virulent P. viticola isolate, which supports the hypothesis that the two subtilases are involved in the early events of the defense mechanisms.

Viral and chemical analyses were performed on 80 dead cats and 51 dead dogs from the Campania Region (Southern Italy), with the aim of evaluating in vivo the potential correlation between coronavirus (CoV) infections and levels of environmental pollutants such as dioxins and PCSs (PCDD/F, DL-PCB and NDL-PCB). The overall viral prevalence was 16.3% in cats and 23.5% in dogs. Both feline coronavirus (FCoV) and canine coronavirus (CCoV) were identified, with variable detection rates in all the other organs investigated, supporting studies that provide evidence of systemic viral spread. The highest prevalence of coronaviruses (CoVs) was observed in Naples (19.2% for FCoV; 30.7% for CCoV) and Caserta (11.1% for FCoV; 50.0% for CCoV), areas that include municipalities with the highest Municipality Index of Environmental Pressure (MIEP) scores. Chemical analyses showed that DL-PCBs were present at more elevated concentrations in CoV-infected dogs and cats than in non-infected animals, whereas ∑NDL-PCB and ∑PCDD/F were detected in greater amounts in non-infected subjects. Among PCDDs, the congener 2,3,7,8-TCDD displayed different distribution patterns between infected and non-infected animals. In cats, 70.0% of FCoV-positive individuals had 2,3,7,8-TCDD levels above the limit of quantification (LOQ), compared with 38.0% of FCoV-negative cats. In dogs, 78.0% of CCoV-infected animals exceeded the LOQ, compared with 20.0% of non-infected ones; this difference was statistically significant. The results of the study suggest that elevated levels of 2,3,7,8-TCDD may be associated with CCoV infection and replication in dogs, suggesting a possible relationship between environmental pollution and susceptibility to coronavirus infections.

ABSTRACT The ability of entomopathogenic fungi to be applied for pest control in field applications is often hampered by negatively active abiotic factors including high temperature, desiccation and UV irradiation. Selecting isolates with high UV tolerance and virulence is important in improving the efficacy and utility of fungal insect pathogens as insect biological control agents for use under field conditions. UV-irradiation of Metarhizium lepidiotae, coupled to growth selection, second metabolites change and insect bioassays using Plutella xylostella larvae as the host resulted in the isolation of a collection of mutants with increased virulence. One mutant, designated, MlUV-40b showed ~3.3-fold increase in virulence as compared to the wild type parent, with an LC50 = 0.3 ×105 conidia/ml versus 1.1 × 105 conidia/ml, respectively and LT50 = 92 and 123.0 h for the MlUV-40b and wild type, respectively. The MlUV-40b mutant displayed increased UV tolerance, but decreased total conidial production. In addition, alterations in the secretome were seen in the mutant. Contact insect toxicity of cell-free culture supernatants and the EthOAc extracts derived from the MlUV-40b mutant were 1.2-3 times more potent than that of the wild type. A simple approach coupling mutagenesis and growth and second metabolites were used to isolate strains with increased stress resistance and virulence. Increased virulence in some of the mutants correlated with increased insecticidal activity in cell-free extracts that could potentially be used directly for insect control.

Disease management programmes in Chilean table grape vineyards use the hydroxyanilide fenhexamid as a pivotal fungicide for Botrytis cinerea control. However, fenhexamid-resistant populations of this pathogen have progressively increased in vineyards under fungicide use. Botrytis cinerea isolates were collected in 'Thompson Seedless' vineyards under fenhexamid control programmes (>two sprays per season) from three regions of Central Chile, during the 2013–2014, 2014–2015 and 2015–2016 growing seasons. Focusing on the 2015–2016 growing season when the greatest level of resistance was measured, only 8% of recovered isolates were sensitive to fenhexamid with 92% of isolates exceeding the sensitivity threshold for mycelium growth. All fenhexamid resistant isolates analyzed carried a mutation in the Erg27 gene, which encodes for 3-keto reductase (3-KR) enzyme. The largest proportion of isolates presented a single-point mutation, leading to a substitution of phenylalanine by serine or isoleucine in the 412 residue of 3-KR (erg27 F412S, 27%; erg27 F412I, 48%). Substitution by valine in this position was observed in a lower proportion of isolates (erg27 F412V, 2%). In contrast to a previous report indicating high fitness cost in isolates carrying erg27 F412S or erg27 F412I, mycelium growth and sclerotia development under different restrictive temperatures were not affected compared to wildtype Erg27 F412 in Chilean mutant isolates. At 0°C, erg27 F412S and erg27 F412I generated larger lesions than erg27 F412V and Erg27 F412 isolates in wounded and unwounded berry assays. Another five mutations were detected in low-resistance Erg27 F412 isolates; one was a previously unreported mutation: erg27 R330P. This study has demonstrated a significant loss of sensitivity to fenhexamid, limited fitness cost and high aggressiveness levels (erg27 F412S and erg27 F412I) in field isolates carrying Erg27 mutations, giving dirctions for the design of Botrytis control programmes based on fenhexamid.

The effects of physical factors such as radiation (electromagnetic, microwave, infrared, laser, UVC, and X-ray) and high temperature, as well as chemical factors (controlled atmosphere) on the level of global DNA cytosine methylation in C. albicans ATCC 10231 cells were investigated. Prolonged exposure to each type of radiation significantly increased the DNA methylation level. In addition, the global methylation level in C. albicans cells increased with the incubation temperature. An increase in the percentage of methylated DNA was also noted in C. albicans cells cultured in an atmosphere with reduced O2. In contrast, in an atmosphere containing more than 3% CO2 and in anaerobic conditions, the DNA methylation level decreased relative to the control. This study showed that prolonged exposure to various types of radiation and high temperature as well as reduced O2 in the atmosphere caused a significant increase in the global DNA methylation level. This is most likely a response protecting DNA against damage, which at the same time can lead to epigenetic disorders, and in consequence can adversely affect the functioning of the organism.

In the current study, a novel strain of Fusarium oxysporum alternavirus 1 (FoAV1) was identified from the Fusarium oxysporum f. sp. melonis (FOM) strain T-BJ17 and was designated as Fusarium oxysporum alternavirus 1-FOM (FoAV1-FOM). Its genome consists of four dsRNA segments of 3515 bp (dsRNA1), 2663 bp (dsRNA2), 2368 bp (dsRNA3), and 1776 bp (dsRNA4) in length. Open reading frame 1 (ORF1) in dsRNA1 was found to encode a putative RNA-dependent RNA polymerase (RdRp), whose amino acid sequence was 99.02% identical to that of its counterpart in FoAV1; while ORF2 in dsRNA2, ORF3 in dsRNA3, and ORF4 in dsRNA4 were all found to encode hypothetical proteins. Strain T-BJ17-VF, which was verified to FoAV1-FOM-free, was obtained using single-hyphal-tip culture combined with high-temperature treatment to eliminate FoAV1-FOM from strain T-BJ17. The colony growth rate, ability to produce spores, and virulence of strain T-BJ17 were significantly lower than those of T-BJ17-VF, while the dry weight of the mycelial biomass and the sensitivity to difenoconazole and pydiflumetofen of strain T-BJ17 were greater than those of T-BJ17-VF. FoAV1-FOM was capable of 100% vertical transmission via spores. To our knowledge, this is the first time that an alternavirus has infected FOM, and this is the first report of hypovirulence and increased sensitivity to difenoconazole and pydiflumetofen induced by FoAV1-FOM infection in FOM.

The concept of a trade-off has long played a prominent role in understanding the evolution of organismal interactions such as mutualism, parasitism, and competition. Given the complexity inherent to interactions between different evolutionary entities, ecological factors may especially limit the power of trade-off models to predict evolutionary change. Here, we use four case studies to examine the importance of ecological context for the study of trade-offs in organismal interactions: (1) resource-based mutualisms, (2) parasite transmission and virulence, (3) plant biological invasions, and (4) host range evolution in parasites and parasitoids. In the first two case studies, mechanistic trade-off models have long provided a strong theoretical framework but face the challenge of testing assumptions under ecologically realistic conditions. Work under the second two case studies often has a strong ecological grounding, but faces challenges in identifying or quantifying the underlying genetic mechanism of the trade-off. Attention is given to recent studies that have bridged the gap between evolutionary mechanism and ecological realism. Finally, we explore the distinction between ecological factors that mask the underlying evolutionary trade-offs, and factors that actually change the trade-off relationship between fitness-related traits important to organismal interactions.

Colibacillosis, caused by avian pathogenic Escherichia coli (APEC) is a major problem for the poultry industry resulting in significant losses annually. Previous work in our lab and by others has shown that the increased serum survival gene (iss) is a common trait associated with the virulence of APEC. This gene was first described for its contributions to E. coli serum resistance. However, recently published research has called the contribution of iss to this trait into question. In the present study, the level of serum resistance conferred on an E. coli isolate by iss is examined. Additionally, the contribution of λ bor gene to E. coli serum resistance is studied, as iss is thought to be derived from bor and bor occurs commonly among E. coli. To better understand the iss and bor contributions to serum resistance, a series of iss and bor mutants was generated. An iss deletion (iss−) mutant showed a significant drop in its resistance to serum. Similarly, a bor mutant showed a drop in serum resistance but not as drastic as that observed with the iss mutant, suggesting that iss contributes more to serum resistance than bor in this E. coli strain. Also, when iss was reintroduced into the iss− mutant the wild-type level of serum resistance was restored, confirming that the deletion of iss was responsible for the change in resistance seen in the mutant.