{"id":2777,"date":"2013-10-23T15:31:39","date_gmt":"2013-10-23T15:31:39","guid":{"rendered":"https:\/\/mycor.iam.inrae.fr\/IAM\/?p=2777"},"modified":"2013-11-06T19:03:26","modified_gmt":"2013-11-06T19:03:26","slug":"phd-defense-y-daguerre","status":"publish","type":"post","link":"https:\/\/mycor.iam.inrae.fr\/IAM\/?p=2777","title":{"rendered":"PhD defense: Y. Daguerre"},"content":{"rendered":"

The defense will take place on Thursday, November 14, 2013 at 13:30 in the amphitheater 16 (first cycle) at the University of Science and Technology from Nancy.<\/p>\n

\u00a0Identifying targets of fungal effectors in the ectomycorrhizal symbiosis Laccaria bicolor-Populus trichocarpa<\/i><\/strong><\/p>\n

<\/div>\n
Roots of most trees form symbiosis with mutualistic soil-borne fungi. The ectomycorrhizal basidiomycete Laccaria bicolor<\/i> (Maire) P.D. Orton relies on mycorrhizal-induced small secreted proteins (MiSSP) to establish symbiotic tissues in the host-plant. The host proteins targeted by these fungal effectors are yet unknown. In the present study, we used the binary yeast two-hybrid (Y2H) system to determine direct interactions between MiSSP7 and the plant proteins in the L. bicolor-P. trichocarpa<\/i> ectomycorrhizae. We showed that MiSSP7 interact with the jasmonic acid (JA) co-receptors JAZ5 and JAZ6 of P. trichocarpa,<\/i> blocking JA signaling and promoting mutualism. L. bicolor <\/i>transformants with severely reduced expression of MiSSP7 did not enter into symbiosis with poplar roots, a phenotype that could be complemented by transgenically varying the transcription of PtJAZ6 <\/i>or through inhibiting JA signalling. Additional Y2H assays showed that PtJAZ6 protein form a regulatory complex involving 14-3-3 protein(s) and MYC transcriptional factors. Two others L. bicolor <\/i>effector-like proteins, MiSSP8 and MiSSP17, are secreted and are essential for the symbiosis development. MiSSP8 showed parietal and plasmalemma localization, while MiSSP17 was mainly cytoplasmic. Y2H assays suggested that these MiSSPs interact with plant proteins involved in plant defence signalling pathways.<\/div>\n
During symbiosis development, L. bicolor<\/i> experiences important genetic reprogramming required for root colonization. Transcription factors (TFs) are key players of these genetic changes. Here, we developed high throughput analysis of TFs in L. bicolor<\/i> to obtain a comprehensive inventory of significantly regulated transcription factors in ECM and showed that some of them display similarities with TFs involved in cell wall integrity, carbon, nitrogen, iron and sulfur metabolism. In addition, Yeast One Hybrid assays allowed the functional validation of 6% of the TFs predicted in silico<\/i> and the identification of Secreted Transcriptional Activator Proteins (STAP) which may be a new class of effectors promoting symbiosis development or\/and controlling rhizospheric microorganisms.<\/div>\n
KeyWords:<\/strong> Effector MiSSP, ectomycorrhizal development, plant defence, mutualistic nutrient exchange, transcription factor, genetic reprogramming.<\/div>\n
<\/div>\n
<\/div>\n
\n
Analyse fonctionnelle d\u2019effecteurs fongiques impliqu\u00e9s dans le d\u00e9veloppement de la symbiose ectomycorhizienne Laccaria bicolor-Populus trichocarpa<\/i><\/strong><\/div>\n
Les racines de la plupart des arbres forment des symbioses ectomycorhiziennes avec les champignons mutualistes du sol. Le basidiomyc\u00e8te Laccaria bicolor<\/i> (Maire) P.D. Orton secr\u00e8te en contexte d\u2019interaction des petites prot\u00e9ines effectrices (MiSSP) afin de faciliter la colonisation de la racine et \u00e9tablir les structures symbiotiques. Toutefois, les prot\u00e9ines de l\u2019h\u00f4te cibl\u00e9es par les MiSSPs de L. bicolor<\/i> ne sont pas encore identifi\u00e9es. Dans notre \u00e9tude, nous d\u00e9montrons, \u00e0 l\u2019aide du syst\u00e8me double hybride chez la levure (Y2H), que la prot\u00e9ine MiSSP7 de L. bicolor<\/i> interagit avec les co-r\u00e9cepteurs de l’acide jasmonique (AJ) JAZ5 et JAZ6 de P.\u00a0trichocarpa<\/i>. Cette interaction prot\u00e9ine-prot\u00e9ine entraine un blocage de la voie de signalisation de l\u2019AJ et favorise le d\u00e9veloppement symbiotique. Des transformants de L. bicolor,<\/i> dont l\u2019expression de MiSSP7 est fortement r\u00e9duite, ne sont plus capables de mycorhizer les racines du peuplier. N\u00e9anmoins, ce ph\u00e9notype peut \u00eatre compl\u00e9ment\u00e9 en faisant varier de fa\u00e7on transg\u00e9nique la transcription de PtJAZ6<\/i> ou par inhibition de la voie de signalisation de l’AJ. A l\u2019aide du syst\u00e8me Y2H, nous avons \u00e9galement mis en \u00e9vidence que la prot\u00e9ine PtJAZ6 est capable d\u2019interagir avec une prot\u00e9ine de type 14-3-3 et un facteur de transcription de type MYC, formant probablement un complexe de r\u00e9gulation. Deux autres prot\u00e9ines effectrices de L. bicolor<\/i>, MiSSP8 et MiSSP17, sont s\u00e9cr\u00e9t\u00e9es et essentielles au d\u00e9veloppement symbiotique. MiSSP8 pr\u00e9sente alors une localisation pari\u00e9tale et plasmalemmique, tandis que MiSSP17 est cytoplasmique. Les r\u00e9sultats des analyses Y2H sugg\u00e8rent que MiSSP8 et MiSSP17 pourraient \u00eatre impliqu\u00e9es dans le contournement des r\u00e9actions de d\u00e9fense de la plante-h\u00f4te.<\/div>\n
Par ailleurs, au cours du d\u00e9veloppement symbiotique, le champignon est le si\u00e8ge d\u2019une reprogrammation g\u00e9n\u00e9tique importante n\u00e9cessaire \u00e0 la colonisation des racines, au contournement des r\u00e9actions de d\u00e9fense de la plante et \u00e0 l’\u00e9tablissement d’\u00e9changes mutualistes. Les facteurs de transcription (TFs) sont les principaux acteurs de ces changements g\u00e9n\u00e9tiques. Nous avons donc \u00e9tudi\u00e9 les TFs de L. bicolor<\/i> afin d\u2019obtenir un inventaire complet des TFs r\u00e9gul\u00e9s par la mycorhization. Certains d’entre eux pr\u00e9sentent des similitudes avec des TFs impliqu\u00e9s dans le maintien de l’int\u00e9grit\u00e9 des parois cellulaires et la r\u00e9gulation du m\u00e9tabolisme du carbone, de l’azote, du fer et du soufre. De plus, le syst\u00e8me simple hybride en levure a permis la validation fonctionnelle de 6% des TFs pr\u00e9dits in silico<\/i> et l’identification de prot\u00e9ines s\u00e9cr\u00e9t\u00e9es capables d\u2019activer la transcription (STAP). Ces derni\u00e8res pourraient constituer une nouvelle classe d’effecteurs favorisant le d\u00e9veloppement symbiotique ou le contr\u00f4le des microorganismes de la rhizosph\u00e8re.<\/div>\n
Mots cl\u00e9s: Effecteur MiSSP, d\u00e9veloppement ectomycorhizien, d\u00e9fenses de la plante, \u00e9change mutualiste de nutriment, facteur de transcription, reprogrammation g\u00e9n\u00e9tique.<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

The defense will take place on Thursday, November 14, 2013 at 13:30 in the amphitheater 16 (first cycle) at the University of Science and Technology from Nancy. \u00a0Identifying targets of fungal effectors in the ectomycorrhizal symbiosis Laccaria bicolor-Populus trichocarpa Roots … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-2777","post","type-post","status-publish","format-standard","hentry","category-seminarmeeting"],"_links":{"self":[{"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=\/wp\/v2\/posts\/2777","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\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2777"}],"version-history":[{"count":0,"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=\/wp\/v2\/posts\/2777\/revisions"}],"wp:attachment":[{"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2777"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2777"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mycor.iam.inrae.fr\/IAM\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2777"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}