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Transcriptome analysis during defense response in the brown alga Laminaria digitata

Audrey Cosse 
Abstract : Host-pathogen interactions in terrestrial plants are well described at the physiological, metabolic or molecular levels. However, defense induction and regulation have hardly been studied in marine macroalgae. In the brown alga Laminaria digitata, studies have shown that oligoguluronates elicit defense responses. Significant progress has been made in understanding the signalling events which produce an oxidative burst and confer late resistance. The halogenated metabolism is particularly active in this species. It seems to be involved in defense responses as indicated by the emission of molecular iodine and volatile halogenated organic compounds after elicitation. In this context, this thesis investigated the transcriptome regulation in response to the perception of oligoluronates by substractive suppressive hybridization, macroarray and real time PCR. Differential expression was confirmed for ten genes encoding haloperoxidases, thioredoxins and pentose phosphate pathway enzymes. Theses results suggest that L. digitata has developed an original strategy to cope with oxidative stress. The importance of halogenated metabolism in defense responses was highlighted by differential expression of haloperoxidase members. The specific regulation of a few members of this multigenic family represents the first report confirming that some haloperoxidase members have evolved toward specialized functions. Identification of these defense molecular markers led to the first identification of the intracellular pathway involving defense genes activation in L. digitata. Hydrogen peroxide was found to be a key actor in different pathways of this signaling cascade. The tools developed and the molecular markers identified in this study should make possible to extend the understanding of defense responses in macroalgae in the context of biotic interactions and longdistance signaling.
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Submitted on : Monday, December 1, 2008 - 8:00:00 AM
Last modification on : Monday, October 19, 2020 - 11:07:51 AM
Long-term archiving on: : Wednesday, September 8, 2010 - 5:54:29 PM


  • HAL Id : pastel-00003673, version 1



Audrey Cosse. Transcriptome analysis during defense response in the brown alga Laminaria digitata. Life Sciences [q-bio]. AgroParisTech, 2007. English. ⟨NNT : 2007AGPT0053⟩. ⟨pastel-00003673⟩



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