14 research outputs found
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, EpicbloĂ« festucae from Festuca gigantea or Koeleria cristata, EpichloĂ« 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/Ăditions scientifiques et mĂ©dicales Elsevier SAS.)Les plantes stressĂ©es (ou attaquĂ©es par un pathogĂšne) montrent gĂ©nĂ©ralement une augmentation de leur activitĂ© peroxydasique. Il a semblĂ© intĂ©ressant dâobserver lâeffet de diffĂ©rents champignons endophytes des graminĂ©es sur lâactivitĂ© peroxydasique de la fĂ©tuque Ă©levĂ©e (var. Clarine) et du ray-grass anglais (var. Vigor). Clarine, artificiellement inoculĂ©e par Neotyphodium coenophialum ou par des e-endophytes isolĂ©s dâautres graminĂ©es (N. lolii et LpTG-2 de Lolium perenne, EpichloĂ« festucae de Festuca gigantea et de Koeleria cristata, EpichloĂ« bromicola de Bromus erectus) montre gĂ©nĂ©ralement une activitĂ© peroxydasique infĂ©rieure ou comparable Ă celle du tĂ©moin. Des rĂ©sultats similaires ont Ă©tĂ© obtenus pour Vigor. En revanche, lâinoculation par un champignon Gliocladium-like, qui appartient au groupe des pendophytes, entraĂźne une augmentation significative de lâactivitĂ© peroxydasique sur les deux espĂšces-hĂŽtes. Ces rĂ©sultats suggĂšrent le caractĂšre quasi-parasitaire des p-endophytes, tandis que les e-endophytes se comporteraient plutĂŽt comme des symbiotes dont la prĂ©sence ne dĂ©clenche pas lâaugmentation de lâactivitĂ© peroxydasique. (© 1999 Inra/Ăditions scientifiques et mĂ©dicales Elsevier SAS.
Infection artificielle du ray-grass anglais et de la fétuque élevée par des champignons endophytes provenant de dix espÚces 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 examinĂ© la capacitĂ© de 15 isolats dâendophytes, provenant de dix espĂšces de graminĂ©es diffĂ©rentes, Ă former des associations avec le ray-grass anglais (Lolium perenne, cv. Vigor) et la fĂ©tuque Ă©levĂ©e (Festuca arundinacea, cv. Clarine). Vingt-deux associations sur trente ont pu ĂȘtre obtenues. Les taxa Neotyphodium lolii, N. coenophialum, LpTG-2, Epichloe festucae, E. bromicola et Gliocladium-like ont Ă©tĂ© capables de sâassocier avec L. perenne et F. arundinacea. Acremonium sp. provenant de L. persicum a pu sâassocier avec L. perenne, mais non avec F. arundinacea. Lâobservation aprĂšs six mois des plantes inoculĂ©es et lâĂ©tude de la transmission du champignon aux graines ont montrĂ© la stabilitĂ© de six associations: la fĂ©tuque Ă©levĂ©e avec N. coenophialum et N. lolii, le ray-grass anglais avec N. lolii, LpTG-2, Epichloe festucae et le Gliocladium-like. Lâisolat dâAcremonium sp. provenant de Lolium persicum ne sâest pas maintenu au-delĂ de quelques mois sur L. perenne.DiffĂ©rentes manifestations dâincompatibilitĂ© ont Ă©tĂ© observĂ©es sur les associations: fĂ©tuque Ă©levĂ©e / LpTG-2, fĂ©tuque Ă©levĂ©e / Gliocladium-like et ray-grass anglais / N. coenophialum. Cette Ă©tude montre que la sĂ©lection de souches dâendophytes pour introduction dans les graminĂ©es fourragĂšres peut ĂȘtre Ă©tendue Ă des endophytes naturellement hĂ©bergĂ©s par dâautres espĂšces de graminĂ©es. (© 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 Alzheimerâs 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