Heterotrimeric G proteins facilitate Arabidopsis resistance to necrotrophic pathogens and are involved in jasmonate signaling.
Heterotrimeric G proteins have been previously linked to plant defense; however a role for the Gbetagamma dimer in defense signaling has not been described to date. Using available Arabidopsis (Arabidopsis thaliana) mutants lacking functional Galpha or Gbeta subunits, we show that defense against the necrotrophic pathogens Alternaria brassicicola and Fusarium oxysporum is impaired in Gbeta-deficient mutants while Galpha-deficient mutants show slightly increased resistance compared to wild-type Columbia ecotype plants. In contrast, responses to virulent (DC3000) and avirulent (JL1065) strains of Pseudomonas syringae appear to be independent of heterotrimeric G proteins. The induction of a number of defense-related genes in Gbeta-deficient mutants were severely reduced in response to A. brassicicola infection. In addition, Gbeta-deficient mutants exhibit decreased sensitivity to a number of methyl jasmonate-induced responses such as induction of the plant defensin gene PDF1.2, inhibition of root elongation, seed germination, and growth of plants in sublethal concentrations of methyl jasmonate. In all cases, the behavior of the Galpha-deficient mutants is coherent with the classic heterotrimeric mechanism of action, indicating that jasmonic acid signaling is influenced by the Gbetagamma functional subunit but not by Galpha. We hypothesize that Gbetagamma acts as a direct or indirect enhancer of the jasmonate signaling pathway in plants.
Trusov
Yuri
Y
Plant Genetic Engineering Laboratory, Department of Botany, School of Integrative Biology, University of Queensland, Brisbane, Queensland 4072, Australia.
Rookes
James Edward
JE
Chakravorty
David
D
Armour
David
D
Schenk
Peer Martin
PM
Botella
José Ramón
JR
D000085:Acetates / Q000494:pharmacology; D000528:Alternaria / Q000472:pathogenicity; D017360:Arabidopsis / Q000033:anatomy & histology / Q000382:microbiology* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D003517:Cyclopentanes / Q000378:metabolism* / Q000494:pharmacology; D005670:Fusarium / Q000472:pathogenicity; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D044388:GTP-Binding Protein gamma Subunits / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007113:Immunity, Innate; D054883:Oxylipins; D021122:Protein Subunits / Q000235:genetics / Q000502:physiology; D044224:Pseudomonas syringae / Q000472:pathogenicity; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000254:growth & development
D000085:Acetates; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D044385:GTP-Binding Protein alpha Subunits; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D054883:Oxylipins; D021122:Protein Subunits; C011006:jasmonic acid; C072239:methyl jasmonate; D020962:Heterotrimeric GTP-Binding Proteins