Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Jeudi 7 mai 2015
Amphi 206 (Cœur d’Ecole) à 14h
The role of annexin 1 from Arabidopsis thaliana in plant’s response to water deficit
Wojciech Rymaszewski, MSc, PhD Student
Institute of Biochemistry and Biophysics PAS, 02-106 Warsaw, Poland
Annexins are calcium- and membrane-binding proteins present in all eukaryotic organisms. Although they were extensively studied for several decades, the exact mechanisms of their functions remain unclear. 8 annexin genes were identified in Arabidopsis thaliana. Annexin 1 (AtANN1, ANNAT1, OXY5) was reported to be expressed in most tissues and its mRNA level was shown to be upregulated in several abiotic stresses, including dehydration. Moreover, AtANN1 knockout mutants (atann1) were more sensitive and overexpressing lines (OE) were more tolerant to water deficit compared to wild-type plants. To explain this observation we looked at first for evidence that AtANN1 protects biological membranes against damage caused by dehydration. Unfortunately, results that we obtained could not explain the whole observed effect. Therefore, we started to characterize AtANN1 properties in more detail. We established that in leaves and roots it localized predominantly in the epidermis and its cellular localization is cytoplasmic and can change only upon very harsh treatment. We showed in vitro, that AtANN1 binds negatively-charged phospholipids only in millimolar calcium concentrations that are unlikely to be present in the cytosol of a living cell. Our recent results suggest that differences in growth under water deficit conditions of atann1 and OEs may be attributed to differences in water loss/transpiration rate. We decided then to analyze the response to water deficit of atann1 and OEs in PHENOPSIS to get a better understanding of their phenotypes. Moreover, we selected 18 Arabidopsis accessions on the basis of AtAnn1 mRNA level, and we are testing them in the same PHENOPSIS experiment to look for connections between AtANN1 expression level and values of measured physiological parameters.
Contact : Christine Granier