Further Contributions to the Development of a Differential Set of Pea Cultivars (Pisum sativum) to Investigate the Virulence of Isolates of Aphanomyces euteiches

Common root rot (Aphanomyces euteiches Drechs.) has become a very destructive disease in the French pea crops since 1993. For an accurate investigation of the virulence variability among French A. euteiches populations and between French and foreign populations, a new set of differential pea genotypes was developed. Thirty-three American and European pea lines, displaying different levels of resistance, were screened in a growth chamber against two French isolates. Symptoms (disease severity from 0 to 5, evaluating symptom surface on roots and epicotyl) and percentage of top fresh weight (inoculated/uninoculated top fresh weight ratio) were measured. From this screening 12 relatively resistant lines, from various genetic backgrounds, were identified along with a highly susceptible control. This set of 13 genotypes was inoculated under controlled conditions with 14 isolates from France, Sweden, USA, Canada and New Zealand, to investigate genotype–isolate interactions. Root symptoms were rated (disease severity), and a susceptibility/resistance threshold was established at disease severity = 1. Significant quantitative interactions were observed, and five 'resistance patterns' were identified, leading to a set of six pea genotypes: Baccara (susceptible), Capella, MN313, 902131, 552 and PI180693. Fields trials of this set in 1999 and 2000 gave the same resistance rankings than in growth chamber conditions. This set will allow more accurate assessments of the variability in virulence/aggressiveness of A. euteiches isolates from France and foreign countries, and further investigations of the epidemiological and genetic basis of pea–A. euteiches interactions.     

Anastomosis Groups, Pathogenicity and Sensitivity to Fungicides of Rhizoctonia solani Isolates Collected on Potato Crops in France

A collection of 241 isolates of Rhizoctonia solani obtained from potato plants grown in different areas in France was characterized for anastomosis grouping, symptomatology on tubers of different cultivars and sensitivity to three fungicides. Most isolates collected belonged to (anastomosis groups (AGs)) AG 3, but 2% and 4% of the isolates were AG 5 and AG 2-1. AG 3 and AG 2-1 isolates were mostly obtained from sclerotia on tubers, but all AG 5, some AG 3 and some AG 2-1 isolates were recovered from superficial tuber alterations, like deformations, corky or scabby lesions. Sclerotia were formed on tubers produced by healthy stem cuttings grown in soil artificially infested with AG 3, but not on tubers grown in soil infested with either AG 5 or AG 2-1. No variation in susceptibility to sclerotial formation was observed among five potato cultivars. In all cases, a large proportion of tubers showed superficial corky lesions, often associated with deformations. The proportion of tubers with lesions and deformations was highest in soil infested with AG 2-1 and significantly lower on cv. Samba in all treatments. All isolates were highly sensitive to flutolanil, iprodione and pencycuron, except the AG 5 isolates, moderately sensitive to pencycuron. These results show that, although AG 3 is the most common R. solani group on potato in France, AG 5 and AG 2-1 may be present. Isolates differed for pathogenicity. In vitro sensitivity to fungicides varied among AGs.     

Neutrophil myeloperoxidase measurements in plasma, laminar tissue, and skin of horses given black walnut extract

OBJECTIVE: To compare measurements of myeloperoxidase (MPO) in plasma, laminar tissues, and skin obtained from control horses and horses given black walnut heartwood extract (BWHE). ANIMALS: 22 healthy 5- to 15-year-old horses. PROCEDURES: Horses were randomly assigned to 4 groups as follows: a control group given water (n = 5) and 3 experimental groups given BWHE (17) via nasogastric intubation. Experimental groups consisted of 5, 6, and 6 horses that received BWHE and were euthanatized at 1.5, 3, and 12 hours after intubation, respectively. Control horses were euthanatized at 12 hours after intubation. Plasma samples were obtained hourly for all horses. Laminar tissue and skin from the middle region of the neck were harvested at the time of euthanasia. Plasma and tissue MPO concentrations were determined via an ELISA; tissue MPO activity was measured by use of specific immunologic extraction followed by enzymatic detection. RESULTS: Tissues and plasma of horses receiving BWHE contained significantly higher concentrations of MPO beginning at hour 3. Laminar tissue and skin from horses in experimental groups contained significantly higher MPO activity than tissues from control horses. Concentrations and activities of MPO in skin and laminar tissues were similar over time. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, BWHE administration causes increases in MPO concentration and activity in laminar tissue and skin and the time of increased MPO concentration correlates with emigration of WBCs from the vasculature. These findings support the hypothesis that activation of peripheral WBCs is an early step in the pathogenesis of acute laminitis.     

Potato Facing Global Challenges: How,How Much,How Well?

This paper surveys issues and developments emerging from the keynotes and participants’ presentations during the 20th EAPR Triennial Conference, held in Versailles, France, in July 2017, and puts them into the perspective of the general theme of the meeting: potato facing global challenges. It reveals important and far-reaching innovations in many areas of potato research, including breeding (genomic selection, high-throughput phenotyping, genome editing), plant protection (biocontrol) and seed production, but also a general innovation approach that follows an incremental pathway (and maintains many existing lock-in situations), and favours substitution strategies over system re-conceptualisation and testing, however urgently needed these might be to achieve or improve the sustainability of potato production in the medium to long run. While the assets and importance of potato as both a wholesome food and an essential part of future worldwide food systems were once more evidenced and highlighted, the contributions also revealed (i) a growing dichotomy between research activities carried out in high-income vs in low- or moderate-income countries, respectively; (ii) some gaps in the assessment of the sustainability of potato production in the medium to long run (external inputs such as fertilisers or pesticides, land and energy use efficiency); and (iii) persistent weaknesses in the integration of individual solutions into complete, operational potato production systems. Some areas for future investigations are identified.     

Astaxanthin from Haematococcus pluvialis Prevents Oxidative Stress on Human Endothelial Cells without Toxicity

Astaxanthin, a powerful antioxidant, is a good candidate for the prevention of intracellular oxidative stress. The aim of the study was to compare the antioxidant activity of astaxanthin present in two natural extracts from Haematococcus pluvialis, a microalgae strain, with that of synthetic astaxanthin. Natural extracts were obtained either by solvent or supercritical extraction methods. UV, HPLC-DAD and (HPLC-(atmospheric pressure chemical ionization (APCI)+)/ion trap-MS) characterizations of both natural extracts showed similar compositions of carotenoids, but different percentages in free astaxanthin and its ester derivatives. The Trolox equivalent antioxidant capacity (TEAC) assay showed that natural extracts containing esters displayed stronger antioxidant activities than free astaxanthin. Their antioxidant capacities to inhibit intracellular oxidative stress were then evaluated on HUVEC cells. The intracellular antioxidant activity in natural extracts was approximately 90-times higher than synthetic astaxanthin (5 µM). No modification, neither in the morphology nor in the viability, of vascular human cells was observed by in vitro biocompatibility study up to 10 µM astaxanthin concentrations. Therefore, these results revealed the therapeutic potential of the natural extracts in vascular human cell protection against oxidative stress without toxicity, which could be exploited in prevention and/or treatment of cardiovascular diseases.