Strategies used by rhizobia to lower plant ethylene levels and increase nodulation

Wenbo Ma, Donna M. Penrose, Bernard R. Glick

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77 Citations (Scopus)


Agriculture depends heavily on biologically fixed nitrogen from the symbiotic association between rhizobia and plants. Molecular nitrogen is fixed by differentiated forms of rhizobia in nodules located on plant roots. The phytohormone, ethylene, acts as a negative factor in the nodulation process. Recent discoveries suggest several strategies used by rhizobia to reduce the amount of ethylene synthesized by their legume symbionts, decreasing the negative effect of ethylene on nodulation. At least one strain of rhizobia produces rhizobitoxine, an inhibitor of ethylene synthesis. Active 1-aminocyclopropane-1-carboxylate (ACC) deaminase has been detected in a number of other rhizobial strains. This enzyme catalyzes the cleavage of ACC to α-ketobutyrate and ammonia. It has been shown that the inhibitory effect of ethylene on plant root elongation can be reduced by the activity of ACC deaminase.

Original languageEnglish
Pages (from-to)947-954
Number of pages8
JournalCanadian Journal of Microbiology
Issue number11
Publication statusPublished - Nov 2002


  • ACC deaminase
  • Ethylene
  • Nodulation
  • Rhizobia
  • Rhizobitoxine

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