Convergence of Signaling Pathways Induced by Systemin, Oligosaccharide Elicitors, and Ultraviolet-B Radiation at the Level of Mitogen-Activated Protein Kinases in Lycopersicon peruvianum Suspension-Cultured Cells1
AUTOR(ES)
Holley, Susan R.
FONTE
The American Society for Plant Biologists
RESUMO
We tested whether signaling pathways induced by systemin, oligosaccharide elicitors (OEs), and ultraviolet (UV)-B radiation share common components in Lycopersicon peruvianum suspension-cultured cells. These stress signals all induce mitogen-activated protein kinase (MAPK) activity. In desensitization assays, we found that pretreatment with systemin and OEs transiently reduced the MAPK response to a subsequent treatment with the same or a different elicitor. In contrast, MAPK activity in response to UV-B increased after pretreatment with systemin and OEs. These experiments demonstrate the presence of signaling components that are shared by systemin, OEs, and UV-B. Based on desensitization assays, it is not clear if the same or different MAPKs are activated by different stress signals. To identify specific stress-responsive MAPKs, we cloned three MAPKs from a tomato (Lycopersicon esculentum) leaf cDNA library, generated member-specific antibodies, and performed immunocomplex kinase assays with extracts from elicited L. peruvianum cells. Two highly homologous MAPKs, LeMPK1 and LeMPK2, were activated in response to systemin, four different OEs, and UV-B radiation. An additional MAPK, LeMPK3, was only activated by UV-B radiation. The common activation of LeMPK1 and LeMPK2 by many stress signals is consistent with the desensitization assays and may account for substantial overlaps among stress responses. On the other hand, MAPK activation kinetics in response to elicitors and UV-B differed substantially, and UV-B activated a different set of LeMPKs than the elicitors. These differences may account for UV-B-specific responses.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=181261Documentos Relacionados
- Suramin inhibits initiation of defense signaling by systemin, chitosan, and a β-glucan elicitor in suspension-cultured Lycopersicon peruvianum cells
- Nod Factor and Elicitors Activate Different Phospholipid Signaling Pathways in Suspension-Cultured Alfalfa Cells1
- A 160-kD systemin receptor on the surface of lycopersicon peruvianum suspension-cultured cells
- Convergence and Divergence of Stress-Induced Mitogen-Activated Protein Kinase Signaling Pathways at the Level of Two Distinct Mitogen-Activated Protein Kinase Kinases
- Prenylcysteine α-Carboxyl Methyltransferase in Suspension-Cultured Tobacco Cells1