Overwintering form of Erysiphe necator, the causal agent of grapevine powdery mildew in southern Syria

Th e main aims of this study were to determine the overwintering form and the primary inoculum of Erysiphe necator, the causal agent of grapevine powdery mildew in southern Syria. Eleven vineyards located at fi ve diff erent geographical sites were visited every week from March to November in 2014 and 2015. Th e results of fi eld and histopathological studies showed that E. necator survived as mycelium in dormant grapevine buds during the winter season. Th e fi rst fl ag shoots were observed shortly aft er bud break in spring. Th e number of fl ag shoots varied greatly according to vineyards, cultivars and years, being present on 27.4 to 61.9% of the grapevines in 2014, and on 5.2 to 40% of the grapevines in 2015. Th e percentage of fl ag shoots on the same grapevine also varied according to the year, cultivar and location. It was between 4.3 to 9.4% in 2014, and 2.1 to 3.6% in 2015. Th e disease was observed only on Balady and Black cultivars. Conidia were released from the second week of May to early September. Th e fi rst conidia were trapped around mid-May, and the fi rst secondary symptoms were observed on leaves from mid-May to early June according to the site. Chasmothecia were observed on leaves in 45.5% of the studied vineyards. Th e fi rst observation of chasmothecia on leaves was in July, and their numbers varied greatly between vineyards and years. Chasmothecia were not detected on bark, nor were ascospores trapped at the beginning of the season. Th ese results confi rmed that the ascospores did not have any role in the initiation of spring infection. To the best of our knowledge, this is the fi rst report of the overwintering form of E. necator in Syria

Activité peroxydasique de plantules de ray-grass anglais et de fétuque élevée inoculée avec des endophytes

International audienceAn increase in peroxidase activity is a common response of plants to various stresses, especially to infection by pathogens. It seemed interesting to study the effects of symbiotic fungi of fodder grasses on the peroxidase activity of their hosts. The peroxidase activity of tall fescue cv. Clarine artificially infected with Neotyphodium coenophialum or with e-endophytes from other hosts (N. lolii and LpTG-2 from Lolium perenne, Epicbloë festucae from Festuca gigantea or Koeleria cristata, Epichloë bromicola from Bromus erectus) was generally either lower or not significantly different from that of the non-infected control. Similar results were obtained with perennial ryegrass cv. Vigor artificially infected with different e-endophytes. In contrast, artificial infection of both grasses with Gliocladium-like fungi belonging to the group of p-endophytes provoked an increase in peroxidase activity. These results suggest that p-endophytes can be considered as parasites while e-endophytes, which are not able to trigger a non-specific host defence response, are really mutualistic. (© 1999 Inra/Éditions scientifiques et médicales Elsevier SAS.)Les plantes stressées (ou attaquées par un pathogène) montrent généralement une augmentation de leur activité peroxydasique. Il a semblé intéressant d’observer l’effet de différents champignons endophytes des graminées sur l’activité peroxydasique de la fétuque élevée (var. Clarine) et du ray-grass anglais (var. Vigor). Clarine, artificiellement inoculée par Neotyphodium coenophialum ou par des e-endophytes isolés d’autres graminées (N. lolii et LpTG-2 de Lolium perenne, Epichloë festucae de Festuca gigantea et de Koeleria cristata, Epichloë bromicola de Bromus erectus) montre généralement une activité peroxydasique inférieure ou comparable à celle du témoin. Des résultats similaires ont été obtenus pour Vigor. En revanche, l’inoculation par un champignon Gliocladium-like, qui appartient au groupe des pendophytes, entraîne une augmentation significative de l’activité peroxydasique sur les deux espèces-hôtes. Ces résultats suggèrent le caractère quasi-parasitaire des p-endophytes, tandis que les e-endophytes se comporteraient plutôt comme des symbiotes dont la présence ne déclenche pas l’augmentation de l’activité peroxydasique. (© 1999 Inra/Éditions scientifiques et médicales Elsevier SAS.

Infection artificielle du ray-grass anglais et de la fétuque élevée par des champignons endophytes provenant de dix espèces différentes de graminées

International audienceThe ability of 15 isolates of endophytic fungi isolated from ten species of grasses to form compatible associations following artificial infection with perennial ryegrass (Lolium perenne, cv. Vigor) and tall fescue (Festuca arundinacea, cv. Clarine) was examined. Twenty-two associations were obtained, only eight failed. The species Neotyphodium lolii, N. coenophialum, LpTG-2, Epichloe festucae, E. bromicola and Gliocladium-like endophyte, could be associated with both L. perenne and F. arundinacea. Acremonium sp. from L. persicum could be associated with L. perenne only. The observation of infected plants after 6 months and the study of mycelial transmission to the seeds showed the stability of the following associations: tall fescue with N. coenophialum and N. lolii, perennial ryegrass with N. lolii, LpTG-2, Epichloe festucae and Gliocladium-like. Acremonium sp. from Lolium persicum was not able to survive in L. perenne for a long time. Various aspects of partial incompatibility were observed among the associations: tall fescue/LpTG-2, tall fescue / Gliocladium-like and perennial ryegrass/N. coenophialum. The study suggests that selection of suitable endophytic strains for fodder grasses can be enlarged to endophytes naturally harboured by other host species. (© Inra/Elsevier, Paris.)On a examiné la capacité de 15 isolats d’endophytes, provenant de dix espèces de graminées différentes, à former des associations avec le ray-grass anglais (Lolium perenne, cv. Vigor) et la fétuque élevée (Festuca arundinacea, cv. Clarine). Vingt-deux associations sur trente ont pu être obtenues. Les taxa Neotyphodium lolii, N. coenophialum, LpTG-2, Epichloe festucae, E. bromicola et Gliocladium-like ont été capables de s’associer avec L. perenne et F. arundinacea. Acremonium sp. provenant de L. persicum a pu s’associer avec L. perenne, mais non avec F. arundinacea. L’observation après six mois des plantes inoculées et l’étude de la transmission du champignon aux graines ont montré la stabilité de six associations: la fétuque élevée avec N. coenophialum et N. lolii, le ray-grass anglais avec N. lolii, LpTG-2, Epichloe festucae et le Gliocladium-like. L’isolat d’Acremonium sp. provenant de Lolium persicum ne s’est pas maintenu au-delà de quelques mois sur L. perenne.Différentes manifestations d’incompatibilité ont été observées sur les associations: fétuque élevée / LpTG-2, fétuque élevée / Gliocladium-like et ray-grass anglais / N. coenophialum. Cette étude montre que la sélection de souches d’endophytes pour introduction dans les graminées fourragères peut être étendue à des endophytes naturellement hébergés par d’autres espèces de graminées. (© Inra/Elsevier, Paris.

Présence et diversité des Acremonium endophytes des graminées. Relations avec les festucoïdées

National audienc

Homotaurine, a safe blood-brain barrier permeable GABAA-R-specific agonist, ameliorates disease in mouse models of multiple sclerosis

Abstract There is a need for treatments that can safely promote regulatory lymphocyte responses. T cells express GABA receptors (GABAA-Rs) and GABA administration can inhibit Th1-mediated processes such as type 1 diabetes and rheumatoid arthritis in mouse models. Whether GABAA-R agonists can also inhibit Th17-driven processes such as experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS), is an open question. GABA does not pass through the blood-brain barrier (BBB) making it ill-suited to inhibit the spreading of autoreactivity within the CNS. Homotaurine is a BBB-permeable amino acid that antagonizes amyloid fibril formation and was found to be safe but ineffective in long-term Alzheimer’s disease clinical trials. Homotaurine also acts as GABAA-R agonist with better pharmacokinetics than that of GABA. Working with both monophasic and relapsing-remitting mouse models of EAE, we show that oral administration of homotaurine can (1) enhance CD8+CD122+PD-1+ and CD4+Foxp3+ Treg, but not Breg, responses, (2) inhibit autoreactive Th17 and Th1 responses, and (3) effectively ameliorate ongoing disease. These observations demonstrate the potential of BBB-permeable GABAA-R agonists as a new class of treatment to enhance CD8+ and CD4+ Treg responses and limit Th17 and Th1-medaited inflammation in the CNS