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A protease of the subtilase family negatively regulates plant defence through its interaction with the Arabidopsis transcription factor AtMYB30

Buscaill, Pierre. A protease of the subtilase family negatively regulates plant defence through its interaction with the Arabidopsis transcription factor AtMYB30. PhD, Interactions plantes-microorganismes, Institut National Polytechnique de Toulouse, 2016

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Abstract

Plants defence responses are often associated with the development of the so-called hypersensitive response (HR), a form of PCD that confines the pathogen to the infection site. The sharp boundary of the HR suggests the existence of efficient mechanisms that control cell death and survival. The Arabidopsis transcription factor AtMYB30 positively regulates plant defence and HR responses by enhancing the synthesis of sphingolipid-containing Very Long Chain Fatty Acids (VLCFA) after bacterial infection. The activity of AtMYB30 is tightly controlled inside plant cells through protein-protein interactions and post-translational modifications. During my PhD, we identified a protease of the subtilase family (AtSBT5.2) as a AtMYB30-interacting partner. Interestingly, we have shown that the AtSBT5.2 transcript is alternatively spliced, leading to the production of two distinct gene products that encode either a secreted [AtSBT5.2(a)] or an intracellular [AtSBT5.2(b)] protein. The specific interaction between AtMYB30 and AtSBT5.2(b), but not AtSBT5.2(a), leads to AtMYB30 specific retention outside of the nucleus in small intracellular vesicles. atsbt5.2 Arabidopsis mutant plants, in which both AtSBT5.2(a) and AtSBT5.2(b) expression was abolished, displayed enhanced HR and defence responses. The fact that this phenotype is abolished in an atmyb30 mutant background suggests that AtSBT5.2 is a negative regulator of AtMYB30-mediated disease resistance. Importantly, overexpression of the AtSBT5.2(b), but not the AtSBT5.2(a), isoform in the atsbt5.2 mutant background reverts the phenotypes displayed by atsbt5.2 mutant plants, suggesting that AtSBT5.2(b) specifically represses AtMYB30-mediated defence.

Item Type:PhD Thesis
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Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
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Research Director:
Rivas, Susana
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Deposited On:13 Feb 2018 08:57

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