{"id":9787,"date":"2019-06-20T13:24:54","date_gmt":"2019-06-20T13:24:54","guid":{"rendered":"https:\/\/mycor.iam.inrae.fr\/IAM\/?p=9787"},"modified":"2019-07-04T11:34:56","modified_gmt":"2019-07-04T11:34:56","slug":"phd-position-epidemiology-of-chalara-ash-dieback","status":"publish","type":"post","link":"https:\/\/mycor.iam.inrae.fr\/IAM\/?p=9787","title":{"rendered":"PhD position: epidemiology of Chalara ash dieback"},"content":{"rendered":"\n

Determinants of inoculum production in the ash dieback\nfungus, Hymenoscyphus fraxineus<\/em><\/strong><\/p>\n\n\n\n

Thesis supervisor B. Mar\u00e7ais\n(benoit.marcais@inra.fr), Thesis Co-Director Marc Bu\u00e9e (UMR IAM, INRA Nancy)<\/p>\n\n\n\n

The introduction of exotic\nfungal species is an important cause of the emergence of forest tree diseases\nand these invasive pathogens often cause devastating epidemics in forests.\nControl measures are limited and a better understanding of natural regulations\nis essential for the development of effective strategies to manage these\ninvasions. Among the possible regulations, the Allee effect (limitation of\npopulation growth at low density) or the effect of microflora associated with\ninoculum reservoirs are poorly characterized for many forest fungal pathogens.\nThe thesis will focus on Chalara ash dieback, a disease that emerged in France\nin 2008 and has since greatly reduced stand productivity, questioning the\ninterest of this species as a forest species.<\/p>\n\n\n\n

The objective of this project\nwill be to better understand what conditions the production of inoculum of H. fraxineus<\/em> in forest stand litter on a\ndensity gradient of the host, the ash tree. We will rely on two existing\nnetworks on which a strong relationship between host density and ash dieback severity\nhas been identified (network of forest stands set up to study the effect of\ndensity and mixing on ash growth, network of stands on a locality to study the\neffect of the landscape on disease evolution). Two questions will be examined\nin more detail: 1) Do the possibilities of encounter of sexual partners\ngenerate a significant Allee effect at low host density for H. fraxineus<\/em>? Can this possible\nlimitation of inoculum production coupled with the limits of dispersion of the\npathogenic fungus explain a threshold effect for the development of the epidemic\nin isolated and small ash populations? 2) Does the microbiota associated with\nash rachis present in the litter respond to host density in the stand and can\nthis affect inoculum production along an ash density gradient?<\/p>\n\n\n\n

This thesis will be carried\nout using a dual approach of modeling and studies of fungal communities\nassociated with ash rachis in litter by metabarcoding. The modeling part will\nextend the work done in Dr. Grosdidier’s thesis that generated the relevant\ndata. The co-supervisors have extensive experience of collaborating on the\nstudy of fungal and forest oomycete communities. This work is part of the H2020\nHOMED project (“Holistic Management of Emerging forest pests and\nDiseases”, 2018-22), which provides funding for the PhD grant and will\nprovide a promising scientific framework on the biology of fungi and invasive\ninsects.<\/p>\n\n\n\n

Applications will be considered in the last week of July (application before July 22, 2019).<\/p>\n\n\n\n

——————————————————————————————————<\/p>\n\n\n\n

D\u00e9terminants\nde la production d\u2019inoculum chez Hymenoscyphus\nfraxineus<\/em>, agent de la chalarose du fr\u00eane<\/strong><\/p>\n\n\n\n

Direction de th\u00e8se B. Mar\u00e7ais (benoit.marcais@inra.fr<\/a>),\nCodirection de th\u00e8se Marc Bu\u00e9e (UMR IAM, INRA Nancy)<\/p>\n\n\n\n

L\u2019introduction d\u2019esp\u00e8ces fongiques exotiques est une\ncause tr\u00e8s importante d\u2019\u00e9mergence de maladies des arbres forestiers et ces\nagents pathog\u00e8nes invasifs provoquent souvent des \u00e9pid\u00e9mies d\u00e9vastatrices dans\nle domaine forestier. Les moyens de lutte sont r\u00e9duits et une meilleure\ncompr\u00e9hension des r\u00e9gulations naturelles est indispensable au d\u00e9veloppement de\nstrat\u00e9gies efficaces de gestion de ces invasions. Parmi les r\u00e9gulations\npossibles, les effets Allee (limitation de la croissance de la population \u00e0\nfaible densit\u00e9) ou l\u2019effet des microflores associ\u00e9es aux r\u00e9servoirs d\u2019inoculum\nsont mal caract\u00e9ris\u00e9s pour de nombreux agents pathog\u00e8nes fongiques forestiers.\nLa th\u00e8se portera sur la chalarose du fr\u00eane, une maladie qui a \u00e9merg\u00e9 en France\nen 2008 et a depuis fortement r\u00e9duit la productivit\u00e9 des peuplements, remettant\nen cause l\u2019int\u00e9r\u00eat de cette esp\u00e8ce comme essence foresti\u00e8re.<\/p>\n\n\n\n

L\u2019objectif de ce projet sera de mieux comprendre ce\nqui conditionne la production d\u2019inoculum d\u2019H.\nfraxineus <\/em>dans la liti\u00e8re des peuplements forestiers sur un gradient de\ndensit\u00e9 de l\u2019h\u00f4te, le fr\u00eane. Nous nous appuierons sur deux r\u00e9seaux existants\nsur lesquels une forte relation entre densit\u00e9 d\u2019h\u00f4te et s\u00e9v\u00e9rit\u00e9 de la\nchalarose ont \u00e9t\u00e9 mis en \u00e9vidence (r\u00e9seau de placettes mis en place pour\n\u00e9tudier l\u2019effet de la densit\u00e9 et du m\u00e9lange sur la croissance du fr\u00eane, r\u00e9seau\nde placettes sur une commune pour \u00e9tudier l\u2019effet du paysage sur l\u2019\u00e9volution de\nla maladie). Deux questions seront examin\u00e9es de fa\u00e7on plus d\u00e9taill\u00e9e : 1)\nEst-ce que les possibilit\u00e9s de rencontre des partenaires sexuels g\u00e9n\u00e8rent un\neffet Allee significatif \u00e0 faible densit\u00e9 d\u2019h\u00f4te pour H. fraxineus <\/em>? Est-ce que cette limitation \u00e9ventuelle de la\nproduction d\u2019inoculum coupl\u00e9e aux limites de la dispersion du champignon\npathog\u00e8ne peut expliquer un effet de seuil pour le d\u00e9veloppement de l\u2019\u00e9pid\u00e9mie\ndans des populations de fr\u00eanes isol\u00e9es et de petite taille ? 2) Le\nmicrobiote associ\u00e9 aux rachis de fr\u00eanes pr\u00e9sents dans la liti\u00e8re r\u00e9pond-il \u00e0 la\ndensit\u00e9 de l\u2019h\u00f4te dans le peuplement et cela peut-il affecter la production\nd\u2019inoculum le long d\u2019un gradient de densit\u00e9 de fr\u00eanes ?<\/p>\n\n\n\n

Cette th\u00e8se sera r\u00e9alis\u00e9e par une double approche de\nmod\u00e9lisation et d\u2019\u00e9tudes des communaut\u00e9s fongiques associ\u00e9es aux rachis de\nfr\u00eanes dans la liti\u00e8re par m\u00e9tabarcoding. La partie de mod\u00e9lisation prolongera\nle travail r\u00e9alis\u00e9 dans le cadre de la th\u00e8se de M. Grosdidier qui a permis de\ng\u00e9n\u00e9rer les donn\u00e9es pertinentes. Les co-encadrants ont une solide exp\u00e9rience de\ncollaboration sur l\u2019\u00e9tude des communaut\u00e9s fongiques et d\u2019oomyc\u00e8tes foresti\u00e8res.\nCe travail s\u2019int\u00e8gre dans le projet H2020 HOMED (\u00ab Holistic Management of\nEmerging forest pests and Diseases \u00bb, 2018-22) qui apporte le financement\nde la bourse et fournira un cadre scientifique porteur sur la biologie des\nchampignons et insectes invasifs.<\/p>\n\n\n\n

Les candidatures seront examin\u00e9es dans la derni\u00e8re semaine de juillet (candidature avant le 22 juillet 2019).<\/p>\n","protected":false},"excerpt":{"rendered":"

Determinants of inoculum production in the ash dieback fungus, Hymenoscyphus fraxineus Thesis supervisor B. Mar\u00e7ais (benoit.marcais@inra.fr), Thesis Co-Director Marc Bu\u00e9e (UMR IAM, INRA Nancy) The introduction of exotic fungal species is an important cause of the emergence of forest tree … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-9787","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=\/wp\/v2\/posts\/9787","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=9787"}],"version-history":[{"count":0,"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=\/wp\/v2\/posts\/9787\/revisions"}],"wp:attachment":[{"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=9787"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=9787"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=9787"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}