Ozone and nitric oxide induce cGMP-dependent and -independent transcription of defence genes in tobacco.
Here, we analyse the temporal signatures of ozone (O3)-induced hydrogen peroxide(H2O2) and nitric oxide (NO) and the role of the second messenger guanosine3′,5′-cyclic monophosphate (cGMP) in transcriptional changes of genes diagnostic for biotic and abiotic stress responses. Within 90 min O3 induced H2O2 and NO peaks and we demonstrate that NO donors cause rapid H2O2 accumulation in tobacco (Nicotiana tabacum) leaf. Ozone also causes highly significant, late (> 2 h) and sustained cGMP increases, suggesting that the second messenger may not be required in all early (< 2 h) responses to O3,but is essential and sufficient for the induction of some O3-dependent pathways.This hypothesis was tested resolving the time course of O3-induced transcript accumulation of alternative oxidase (AOX1a), glutathione peroxidase (GPX),aminocyclopropancarboxylic acid synthase (ACS2) that is critical for the synthesis of ethylene, phenylalanine ammonia lyase (PALa) and the pathogenesis-related protein PR1a.The data show that early O3 and NO caused transcriptional activation of the scavenger encoding proteins AOX1a, GPX and the induction of ethylene production through ACS2 are cGMP independent. By contrast, the early response of PALa and the late response of PR1a show critical dependence on cGMP.
Pasqualini
Stefania
S
Department of Applied Biology, University of Perugia, I-06121 Italy.
Meier
Stuart
S
South African Institute of Bioinformatics, and.
Gehring
Chris
C
Department of Biotechnology, University of the Western Cape, Bellville, 7535, South Africa.
Madeo
Laura
L
Department of Applied Biology, University of Perugia, I-06121 Italy.
Fornaciari
Marco
M
Department of Applied Biology, University of Perugia, I-06121 Italy.
Romano
Bruno
B
Department of Applied Biology, University of Perugia, I-06121 Italy.
Ederli
Luisa
L
Department of Applied Biology, University of Perugia, I-06121 Italy.
D006152:Cyclic GMP / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D010126:Ozone / Q000494:pharmacology*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018749:RNA, Plant / Q000378:metabolism; D014026:Nicotiana / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
D010940:Plant Proteins; D018749:RNA, Plant; D009569:Nitric Oxide; D010126:Ozone; D006861:Hydrogen Peroxide; D006152:Cyclic GMP