Indolyl-3-butyric acid-induced Arabidopsis stomatal opening mediated by 3',5'-cyclic guanosine-monophosphate.
It has been pharmacologically suggested that 3',5'-cyclic guanosine-monophosphate (cGMP) mediates indolyl-3-butyric acid (IBA)-induced stomatal opening. In Arabidopsis thaliana (L.) Heynh., such investigations compared the wild type (Columbia and Ws ecotypes) to mutants knockout for either GTP-binding protein (G protein) α subunit 1 (gpa1-4), putative G protein-coupled receptor 1 (gcr1-5), calcineurin B-like isoform 1 (cbl1) or 9 (cbl9), or the NADPH oxidases AtrbohD and AtrbohF (atrbohD/F). Stomatal opening to IBA or the permeant cGMP analogue, 8-bromo-cGMP (8-Br-cGMP) was abolished in the atrbohD/F mutant. The IBA response was fully or partially suppressed, respectively, in the gcr1-5 mutant, or the gpa1-4 and cbl1 mutants. In the cbl9 mutant, the response to IBA or 8-Br-cGMP, respectively, was partially or fully suppressed. Phenylarsine oxide (PAO) affected the IBA response, which the cbl1 mutant overlapped or the gpa1-4 and cbl9 mutants increased up to 100% inhibition. 6-anilino-5,8-quinolinedione, mas17, the (Rp)-diastereomer of 8-bromo-3',5'-cyclic guanosine monophosphorothioate (Rp-8-Br-cGMPS), nicotinamide, ruthenium red (RRed), 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), cyclosporine A (CsA) and FK506 converged to affect the IBA response, which the gpa1-4 and cbl9 mutants overlapped or the cbl1 mutant and PAO increased up to 100% inhibition. Rp-8-Br-cGMPS, nicotinamide, RRed, BAPTA, CsA or FK506 paralled the cbl9 and atrbohD/F mutants to abolish the 8-Br-cGMP response. Based on so far revealed features of these mutants and pharmacological compounds, these results confirmed cGMP as a Ca(2+)-mobilizing second messenger for apoplastic auxin whose perception and transduction would implicate a seven-transmembrane receptor - G protein - guanylyl cyclase unit at the guard cell plasma membrane.
Cousson
A
A
CEA, DSV, IBEB, Lab Echanges Membran & Signalisation, Saint-Paul-lez-Durance F-13108, France. alain.cousson@cea.fr
D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D001152:Arsenicals / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism*; D006162:Guanylate Cyclase / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology*; D009154:Mutation; D054046:Plant Stomata / Q000187:drug effects* / Q000502:physiology; D015290:Second Messenger Systems / Q000502:physiology*; D015398:Signal Transduction
D001152:Arsenicals; D007210:Indoleacetic Acids; D007211:Indoles; C014612:indolebutyric acid; C029341:oxophenylarsine; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D002118:Calcium