How alfalfa root hairs discriminate between Nod factors and oligochitin elicitors

H. H. Felle, É. Kondorosi, A. Kondorosi, M. Schultze

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)1373-1380
Number of pages8
JournalPlant Physiology
Volume124
Issue number3
Publication statusPublished - 2000

Fingerprint

alkalinization
Medicago sativa
root hairs
alfalfa
acidification
calcium
cytosol
signal transduction
ions
elicitors
N-acetylchitooctaose
Microelectrodes
cells
Cytosol
Rhizobium meliloti Nod factor IV
Ions

ASJC Scopus subject areas

  • Plant Science

Cite this

How alfalfa root hairs discriminate between Nod factors and oligochitin elicitors. / Felle, H. H.; Kondorosi, É.; Kondorosi, A.; Schultze, M.

In: Plant Physiology, Vol. 124, No. 3, 2000, p. 1373-1380.

Research output: Contribution to journalArticle

Felle, HH, Kondorosi, É, Kondorosi, A & Schultze, M 2000, 'How alfalfa root hairs discriminate between Nod factors and oligochitin elicitors', Plant Physiology, vol. 124, no. 3, pp. 1373-1380.
Felle, H. H. ; Kondorosi, É. ; Kondorosi, A. ; Schultze, M. / How alfalfa root hairs discriminate between Nod factors and oligochitin elicitors. In: Plant Physiology. 2000 ; Vol. 124, No. 3. pp. 1373-1380.
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