Towards identification of active root-secreted proteases of Arabidopsis thaliana.

Poster (2013, April 18)

Besides traditional production systems, such as bacteria, yeasts and mammal cells, plants can now be used to produce eukaryotic recombinant proteins. Their advantages as hosts for proteins production ... [more ▼]

Besides traditional production systems, such as bacteria, yeasts and mammal cells, plants can now be used to produce eukaryotic recombinant proteins. Their advantages as hosts for proteins production include correct post-translational modifications, low cost of maintenance and no risk of contamination by human pathogens. Targeting heterologous proteins to the extracellular space is required for the correct folding of complex proteins and makes harvesting and purification easier. However, the quantity and the quality of recombinant proteins have been proved to be reduced by the action of endogenous co-secreted proteases. In this study, we characterized root-secreted proteases in the model plant Arabidopsis thaliana, at the activity and expression levels. Their activity was analyzed by in vitro degradation of a target protein (Bovine Serum Albumine, BSA) in a range of pH and in the presence of several proteases inhibitors. Serine proteases were identified as the major protease class involved in the degradation of BSA under all tested conditions. As a first step towards the identification of the key players, the expression level of selected members of this class was analyzed by quantitative RT-PCR in roots and leaves. [less ▲]

Implication of microRNAs in the response of Brachypodium distachyon (L.) Beauv. root system architecture to rhizobacterial volatiles

Scientific conference (2013, February)

The metabolic roles of volatile organic compounds (VOCs) emitted by plant growth-promoting rhizobacteria (PGPR) and the identity of the molecules responsible for the growth promotion are still poorly ... [more ▼]

The metabolic roles of volatile organic compounds (VOCs) emitted by plant growth-promoting rhizobacteria (PGPR) and the identity of the molecules responsible for the growth promotion are still poorly documented. As well, the implication of microRNAs in root development is a recent discovery that deserves to be explored. In this study, the implication of microRNAs in the response of Brachypodium distachyon (L.) Beauv. Bd21 root architecture to rhizobacterial VOCs was investigated. Nineteen PGPR strains were screened to select those showing the strongest phenotypic effects. The strain Bacillus subtilis AP305-GB03 induced the most important promotion of biomass production and root development. Total RNA extraction and RT-qPCR analysis of microRNAs were performed on Bd21 root samples. The expression of miR160 a-d, miR164 f, miR167 c-d, miR397 b and miR399 a-b was measured in roots every 2 days during the first 10 days of Bd21 development, in the presence or absence of the bacterial VOCs. Differences in the expression profile of miR164 f and miR167 c-d were observed in the roots exposed to GB03 VOCs, as compared to the control. These differences could be correlated to the root system architecture modifications observed after 10 days of growth with GB03. miR397 b and miR399 a-b also showed differences in the expression profile of roots exposed to the bacterial VOCs. These microRNAs have been respectively involved in cold stress tolerance and in the response to phosphate starvation. [less ▲]

Etudes physiologiques et génétiques de la floraison: regards croisés entre Arabidopsis et des espèces cultivées

Scientific conference (2012, December 18)

Comment les plantes fleurissent-elles ?

Conference given outside the academic context (2012)

Effects of flowering on root architecture in Arabidopsis

Poster (2012, May)

Degradation of recombinant IgG by root-secreted proteases of Arabidopsis thaliana and Nicotiana tabacum

Poster (2012, April 18)

Plants are promising hosts for the production of complex recombinant pharmaceuticals, such as antibodies (mAbs), because they offer an inexpensive and safer alternative to traditional production systems ... [more ▼]

Plants are promising hosts for the production of complex recombinant pharmaceuticals, such as antibodies (mAbs), because they offer an inexpensive and safer alternative to traditional production systems. The plant-based production of mAbs, which are multimeric glycoproteins, require their targeting to the secretory pathaway where they are properly folded and matured. However, co-secretion of endogenous proteases, which can represent up to 10% of the extracellular proteins (secretome), is known to significantly alter the yield and quality of secreted mAbs. In this study, we analyzed the proteolytic activities in root-secretome of Arabidopsis thaliana and Nicotiana tabacum. Root-secretomes were recovered by salt extraction and the protease activity was assayed in vitro or by zymography, in a range of pH. The relative contribution of protease classes was evaluated with specific inhibitors. [less ▲]

Water stress drastically reduces root growth and inulin yield in Cichorium intybus (var. sativum) independently of photosynthesis

in Journal of Experimental Botany (2012), in press

Root chicory (Cichorium intybus var. sativum) is a cash crop cultivated for inulin production in Western Europe. This plant could be exposed to severe water stress during the three last months of their ... [more ▼]

Root chicory (Cichorium intybus var. sativum) is a cash crop cultivated for inulin production in Western Europe. This plant could be exposed to severe water stress during the three last months of their six months growing period. The aim of this study was to quantify the effect of a progressive decline in water availability on plant growth, photosynthesis and sugar metabolism and to determine its impact on inulin production. Water stress drastically decreased root fresh and dry weight, leaf number, total leaf area and stomatal conductance. Stressed plants, however, increased their water use efficiency, decreased the shoot to root ratio and lowered their osmotic potential through soluble sugar accumulation. Despite a decrease in photosynthetic pigments, the light phase of the photosynthesis remained unaffected under water stress. Water stress increased sucrose phosphate synthase (SPS) activity in the leaves, but not in the roots. Water stress inhibited sucrose:sucrose 1-fructosyltransferase (1-SST) and fructan:fructan 1 fructosyltransferase (1—FFT) after 19 weeks of culture and slightly increased fructan 1-exohydrolase activities (1-FEH). The root inulin concentration and the mean degree of polymerisation (DP) of the inulin chain remained however unaffected by water stress. It is concluded that root chicory displayed resistance to water stress, but that such a resistance is obtained at the expense of growth which, in turn, leads to significant decrease in inulin production. [less ▲]

Un anticorps monoclonal matrice optimisé pour la production en cellules végétales et pour l’immobilisation en surface

Report (2011)

Genetic interactions shaping the inflorescence of tomato

Conference (2011, June)

A cytokinin route to flowering in Arabidopsis

Poster (2011, June)

Cytokinins (CKs) are involved in many physiological processes. We observed that the application of N6-benzylaminopurine (BAP) to the roots of hydroponically grown plants of Arabidopsis thaliana promotes ... [more ▼]

Cytokinins (CKs) are involved in many physiological processes. We observed that the application of N6-benzylaminopurine (BAP) to the roots of hydroponically grown plants of Arabidopsis thaliana promotes flowering in non-inductive short days. The response to BAP treatment does no require FLOWERING LOCUS T (FT), but activates its paralogue TWIN SISTER OF FT (TSF), as well as FD and SUPPRESSOR OF OVEREXPRESSION OF CO1 (SOC1) (D'Aloia et al., 2011). We present here complementary data obtained with transgenic plants overexpressing a catalytic CK OXIDASE/DEHYDROGENASE (CKX) in the roots. The high efficiency of BAP in promoting flowering in our experimental system contrasts with the variability that emerges from studies gathered in literature. Many factors, either experimental or inherent to plant material, might explain these discrepancies and we are interested in identifying endogenous regulators that might provide a mechanistic explanation. We are therefore investigating whether the endogenous pathways underlying plant developmental phase changes might regulate the relative contribution of CKs to flowering. [less ▲]