Séminaire IBIP
Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)

Jeudi 4 juillet 2013
Amphi 2 (Bât. 2 Bis) à 14h

The VASCULATURE COMPLEXITY AND CONTINUITY (VCC) gene encodes a plant-specific protein required for embryo provasculature development

Hannetz Roschzttardtz
Marisa S. Otegui’s lab – Department of Botany University of Wisconsin-Madison

The molecular mechanisms by which vascular tissues acquire their identity are largely unknown. In this seminar, I will present the identification and characterization of a gene, VCC (VASCULATURE COMPLEXITY AND CONTINUITY), member of a 15-member plant-specific gene family in Arabidopsis thaliana that encodes proteins of unknown function with four predicted transmembrane domains. Homozygous vcc mutants display cotyledon vein patterns of reduced complexity and discontinuous veins. The embryonic endodermis visualized by iron-specific staining shows similar discontinuities in the provasculature of vcc embryos, indicating that defects in vein patterning appear early in mutant embryo development. Consistently, the overexpression of VCC leads to an unusually high proportion of cotyledons with vein patterns of high complexity. The analysis of the vcc mutants indicates that neither auxin distribution nor the polar localization of the auxin-efflux carrier, is affected in vcc mutant embryos. Expression of VCC is detected in procambial, cambial, and phloem cells in cotyledons, leaves, roots, hypocotyls, and anthers, and during in vitro secondary growth induction in inflorescence stems. To evaluate possible genetic interactions with other genes that control vasculature patterning in embryos, we generated a double mutant for VCC and OCTOPUS (OPS). The vcc ops double mutant embryos show a complete loss of high-complexity cotyledon vein patterns and a drastic increase in vascular discontinuities. Embryonic iron distribution is also affected in vcc ops. These results suggest that VCC and OPS work synergistically in the establishment of cotyledon vein patterning.

Contact : Stéphane Mari

Contacts IBIP :
Sabine Zimmermann
Philippe Nacry
Christine Granier
Chantal Baracco