Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Jeudi 16 mai 2013
salle 104 (château) à 14h
Ion homeostasis as the non-transcriptional mechanism of plant hormones and abiotic stress
Instituto de Biología Molecular y Celular de Plantas-Universidad Politécnica de Valencia-CSIC Valencia, Spain
Plant hormonal and stress responses have both transcriptional and non-transcriptional mechanisms, the latter consisting on alterations in ion homeostasis. We have investigated regulation of H+ pumping and K+ transport by imposing intracellular acidification with weak organic acids (acetic acid) and selecting tolerant mutants tagged with T-DNA. Over-expression of prolyl-isomerase ROF2 and loss-of-function of AP-3 beta-adaptin (wat1-1D) improve pH homeostasis by stimulating K+ transport and H+ efflux. Growth of these and other mutants with improved pH homeostasis (ost2-1D, over-expression of AKT1) is more tolerant to ABA than wild type during germination and early seedling growth. ABA inhibits the activity of plasma membrane H+-ATPase, H+ efflux and K+ transport and this requires ABA receptors (PYR-PYL), phosphatases PP2Cs and kinases SnRK2s. Electrophysiological measurements indicate that in root epidermal cells ABA induces intracellular acidification and K+ depletion in wild type but not in wat1-1D or in a mutant of ABA receptors. These results suggest that one mechanism for ABA to inhibit growth is to alter pH and K+ homeostasis.
Contact : Isabelle Chérel