Cucumis metuliferus is resistant to root‐knot nematode Mi1.2 gene (a)virulent isolates and a promising melon rootstock

Pot experiments were carried out to characterize the response of two Cucumis metuliferus accessions (BGV11135 and BGV10762) against Mi1.2 gene (a)virulent Meloidogyne arenaria, M. incognita and M. javanica isolates and to determine the compatibility and the effect on physicochemical properties of fruit melons. In addition, histopathological studies were conducted. One week after transplanting, plants were inoculated with one J2 cm^?3 of sterilized sand (200 cm³ pots) and maintained in a growth chamber at 25 °C for 40 days. The susceptible cucumber cv. Dasher II or melon cv. Paloma were included for comparison. The number of egg masses and number of eggs per plant were assessed, and the reproduction index (RI) was calculated as the percentage of eggs produced on the C. metuliferus accessions compared to those produced on the susceptible cultivars. The compatibility and fruit quality were assessed by grafting three scions, two of Charentais type and one of type piel de sapo, under commercial greenhouse conditions. The resistance level of both C. metuliferus accessions ranged from highly resistant (RI < 1%) to resistant (1% ≤ RI ≤ 10%) irrespective of Meloidogyne isolates. Melon plants grafted onto C. metuliferus accession BGV11135 grew as self‐grafted plants without negatively impacting fruit quality traits. Giant cells induced by Meloidogyne spp. on C. metuliferus were in general poorly developed compared to those on cucumber. Furthermore, necrotic areas surrounding the nematode were observed. Cucumis metuliferus accession BGV11135 could be a promising melon rootstock to manage Meloidogyne spp., irrespective of their Mi1.2 (a)virulence, without melon fruit quality reduction.     

Suspect West Nile virus encephalomyelitis in an imported horse in the UK

This report describes a suspect case of West Nile virus (WNV) encephalomyelitis, reported for the first time in a horse in the UK. The affected gelding had been imported from the Republic of Cyprus and travelled through several WNV endemic areas in Europe before arriving at the premises in Lincolnshire. Clinical signs included muscle fasciculations, weakness of the hindlimbs and transient lip twitching that quickly progressed to depression and recumbency. West Nile virus specific antibodies were detected by serological tests in the absence of a previous history of vaccination. The horse improved clinically 10 days after the onset of disease and fully recovered in 12 weeks. Follow‐ups at 12 and 20 months post event did not reveal any sequela and the horse was performing adequately at novice level. This article refers to the same horse mentioned by Fooks et al. (2014) and it is an extension of the previous published work.     

Effect of salicylic acid treatment on tomato plant physiology and tolerance to potato virus X infection

Salicylic acid (SA) is an inducer of systemic acquired resistance (SAR) and could be a potential candidate in the control of plant virus diseases. In this study we assayed under controlled conditions the potential effect of three doses of exogenous SA treatment on tomato plants infected with Potato virus X (PVX) and measured their effects on: different physiological parameters (gas exchange, stable isotopes, chlorophyll content), the activation of secondary metabolism, viral accumulation and induction of the expression of pathogenesis-related proteins (PRs) such as ß-1, 3-glucanase (PR2) and chitinase (PR3). SA treatment increased the expression of PR2, the activity of phenylalanine ammonia lyase (PAL) and the concentration of antioxidant compounds at 7 days post-treatment. Earlier expression of PR3 compared to PR2 was observed. SA treatment delayed the detection of PVX by ELISA in uninoculated leaves of mechanically infected tomato plants. Although the effect of PVX infection on physiological parameters was weak, moderate SA treatments showed enhanced photosynthesis, particularly for infected plants. The results obtained confirm that SA promotes major changes in the induction of resistance in tomato plants and suggest that treatment with exogenous SA could be considered to reduce the infections caused by PVX.     

Cryphonectria hypovirus 1 (CHV‐1) survey reveals low occurrence and diversity of subtypes in NE Spain

Cryphonectria parasitica (Murrill.) Barr is a necrotrophic fungus that affects European chestnut populations. In Catalonia (NE Spain), this fungus is widely spread affecting chestnut stands. In addition to vegetative compatibility (VC) types of the fungus, knowledge of the Cryphonectria hypovirus (CHV) occurrence is important to implement a biocontrol programme. We confirmed the presence of hypoviruses in several chestnut subpopulations of Catalonia, and we determined the VC types of CHV‐infected isolates. We also studied the nucleotide sequences of these hypoviruses from a variable region located in the hypovirus ORF‐A. Our results show a low occurrence of hypoviruses throughout C. parasitica populations in Catalonia, except for a few localized stands. From 312 sampled cankers, we obtained 179 white, pale orange or rickety isolates. In 35 of them, we detected CHV‐1. Infected isolates belonged to 5 of the 7 sampled subpopulations. We found 12 CHV‐1 haplotypes, based on the nucleotide sequence analysis. Most of the hypoviruses have the same nucleotide sequence or show high homology at nucleotide level with isolates previously included in CHV‐1 subtype‐I. However, we found that 3 haplotypes share at least 97% of their ORF‐A nucleotide sequence with CHV‐1 subtype‐E. Phylogenetic analysis grouped these 3 isolates in a different cluster than the other hypoviruses. These results suggest that multiple introductions of CHV‐1 have occurred recently in Catalonia. Dominant VC types of hypovirus‐infected isolates are EU‐1, EU‐2 and EU‐5, which are similar to those previously reported in this region.     

The Effects of Soil Solarization and Compost on Soil Suppressiveness against Fusarium Oxysporum f. sp. Melonis

Soil suppressiveness against Fusarium was tested using solarized and non-solarized soils combined with composts of three maturation levels, and a non-amended control. The soils were sampled on three dates: after previous year solarization but before current year solarization (0 weeks), at the end of the solarization period of the current year (4 weeks), and 4 weeks later (recovery time). Melon seedlings were inoculated with Fusarium spores and disease severity was assessed. The study showed a reduction of soil suppressiveness capacity against Fusarium oxysporum f. sp. melonis after 1 year of solarization (0 weeks). Fusarium disease severity in artificially inoculated melon plants, expressed by area under the disease progress curve, was higher in solarized soil than in non-solarized soil. Compost addition lowered the disease severity, both in the solarized and in the non-solarized soils. However, suppression was not obtained at the end of the solarization period, whereas compost beneficial effect was found at this time.     

Effects of spent mushroom substrates and inorganic fertilizer on the characteristics of a calcareous clayey‐loam soil and lettuce production

We evaluated the effects of the addition of two types of spent mushroom substrate (SMS), SMS from an Agaricus bisporus crop (SMS1) and a mixture of SMSs from an A. bisporus crop and a Pleurotus crop (50% v/v each) (SMS2), on the characteristics of a calcareous clayey‐loam soil and the yield and nutritional status of lettuce (Lactuca sativa L.), relative to crops receiving mineral fertilizer (M) and a control (C) without amendment. The application of SMS, especially SMS1, improved soil fertility compared with C and M soils. Moreover, the use of these organic substrates as soil amendments did not harm the plants and gave yields similar to that obtained with mineral fertilizer. The nutritional contents of the lettuce plants were greater than or similar to those of the plants from treatment C or M, except for the plant tissue concentrations of K, Fe and Zn, which were significantly reduced by SMS application. However, this latter fact did not reduce the lettuce yield in the amended soils. Therefore, the use of SMSs as organic amendments contributes to residue utilization, in an environmentally friendly way, and to improved soil fertility and crop yield.     

Proteins and Carbohydrates from Red Seaweeds: Evidence for Beneficial Effects on Gut Function and Microbiota

Based on their composition, marine algae, and namely red seaweeds, are good potential functional foods. Intestinal mucosal barrier function refers to the capacity of the intestine to provide adequate containment of luminal microorganisms and molecules. Here, we will first outline the component of seaweeds and will summarize the effects of these on the regulation of mucosal barrier function. Special attention will be paid to unique components of red seaweeds: proteins and derived peptides (e.g., phycobiliproteins, glycoproteins that contain “cellulose binding domains”, phycolectins and the related mycosporine-like amino acids) together with polysaccharides (e.g., floridean starch and sulfated galactans, such as carrageenans, agarans and “dl-hybrid”) and minerals. These compounds have been shown to exert prebiotic effects, to regulate intestinal epithelial cell, macrophage and lymphocyte proliferation and differentiation and to modulate the immune response. Molecular mechanisms of action of peptides and polysaccharides are starting to be elucidated, and evidence indicating the involvement of epidermal growth factor receptor (EGFR), insulin-like growth factor receptor (IGFR), Toll-like receptors (TLR) and signal transduction pathways mediated by protein kinase B (PKB or AKT), nuclear factor-κB (NF-κB) and mitogen activated protein kinases (MAPK) will also be summarized. The need for further research is clear, but in vivo experiments point to an overall antiinflammatory effect of these algae, indicating that they can reinforce membrane barrier function.