How Alfalfa Root Hairs Discriminate between Nod Factors and Oligochitin Elicitors1
AUTOR(ES)
Felle, Hubert H.
FONTE
American Society of Plant Physiologists
RESUMO
Using ion-selective microelectrodes, the problem of how signals coming from symbiotic partners or from potential microbial intruders are distinguished was investigated on root hairs of alfalfa (Medicago sativa). The Nod factor, NodRm-IV(C16:2,S), was used to trigger the symbiotic signal and (GlcNAc)8 was selected from (GlcNAc)4-8, to elicit defense-related reactions. To both compounds, root hairs responded with initial transient depolarizations and alkalinizations, which were followed by a hyperpolarization and external acidification in the presence of (GlcNAc)8. We propose that alfalfa recognizes tetrameric Nod factors and N-acetylchitooligosaccharides (n = 4–8) with separate perception sites: (a) (GlcNAc)4 and (GlcNAc)6 reduced the depolarization response to (GlcNAc)8, but not to NodRm-IV(C16:2,S); and (b) depolarization and external alkalization were enhanced when NodRm-IV(C16:2,S) and (GlcNAc)8 were added jointly without preincubation. We suggest further that changes in cytosolic pH and Ca2+ are key events in the transduction, as well as in the discrimination of signals leading to symbiotic responses or defense-related reactions. To (GlcNAc)8, cells responded with a cytosolic acidification, and they responded to NodRm-IV(C16:2,S) with a sustained alkalinization. When both agents were added jointly, the cytosol first alkalized and then acidified. (GlcNAc)8 and NodRm-IV(C16:2,S) transiently increased cytosolic Ca2+ activity, whereby the response to (GlcNAc)8 exceeded the one to NodRm-IV(C16:2,S) by at least a factor of two.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=59234Documentos Relacionados
- Correlation between Binding Affinity and Necrosis-Inducing Activity of Mutant AVR9 Peptide Elicitors1
- Nod Factor and Elicitors Activate Different Phospholipid Signaling Pathways in Suspension-Cultured Alfalfa Cells1
- Respiratory Elicitors from Rhizobium meliloti Affect Intact Alfalfa Roots1
- How flowering plants discriminate between self and non-self pollen to prevent inbreeding.
- Alfalfa Enod12 genes are differentially regulated during nodule development by Nod factors and Rhizobium invasion.