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Identification des modules de la signalisation auxinique impliqués dans la morphogenèse foliaire

Abstract : Auxin is essential for plant development, more particularly by participating in cellular division andexpansion. Transcription of auxin response genes is allowed by the auxin signaling pathway involving the F-boxTIR1/AFBs proteins associated to ubiquitin ligase E3, which can interact with the AUX/IAA repressors in thepresence of auxin to trigger their degradation and activate transcription of early auxin response genes involvingthe Auxin Response Factors (ARF). At the leaf margin, an auxin maximum resulting from the transport of auxinmediated by the auxin efflux carrier PIN1 is required for teeth formation. The transcription factor CUC2 thatdefines boundary domains, somehow redirects PIN1 to create a convergent flux to the apex of the tooth. Auxinrepresses CUC2 thus limiting its expression to the sinus. In Arabidopsis, the actors of the auxin signalingpathway involved in leaf serration are unknown.In this thesis, the expression profiles of ARFs genes have been investigated in young leaves of Arabidopsis, morespecifically during teeth formation and a detailed map was built. Three ARFs acting as putative repressors ARF1,ARF3 and ARF18 and three activators ARF5, ARF6 and ARF8 were identified as been expressed in thesinus/teeth area. Their expression profiles were also studied in leaves exhibiting modified shapes as a result ofvariations in CUC2 expression. To determine if these ARFs are involved in leaf morphogenesis and moreparticularly in tooth initiation, the arf5-2 null mutant and the double null mutants arf6-2 arf8-3, arf1-5 arf3-1,arf1-5 arf18-2 and arf3-1 arf18-2 were generated and serration was analyzed. Length of arf5-2 mature leaves islonger than the wild type, suggesting that ARF5 could be involved in cell expansion.
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Manon Boudin. Identification des modules de la signalisation auxinique impliqués dans la morphogenèse foliaire. Biologie végétale. Université Paris Saclay (COmUE), 2017. Français. ⟨NNT : 2017SACLS463⟩. ⟨tel-01688818⟩

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