Rhizobitoxine-induced chlorosis occurs in coincidence with methionine deficiency in soybeans

Shin Okazaki, Masayuki Sugawara, Ken Ichi Yuhashi, Kiwamu Minamisawa

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

• Background and Aims: Rhizobitoxine, produced by the legume symbiont Bradyrhizobium elkanii, inhibits cystathionine-β-lyase (EC 4.4.1.8) in methionine biosynthesis and 1-aminocyclopropane-1-carboxylate synthase (ACC) in ethylene biosynthesis. Rhizobitoxine production by B. elkanii enhances nodulation of host legumes via the inhibition of ethylene synthesis, but causes foliar chlorosis in susceptible soybeans, though how it does so remains to be investigated. The aim of this study was to examine the physiological basis of rhizobitoxine-induced chlorosis in soybeans. • Methods: Wild-type B. elkanii and a rhizobitoxine-deficient mutant were inoculated in Glycine max 'Lee'. Thirty days after inoculation, the upper parts of soybean shoots were analysed for amino acid contents. Chlorotic soybeans inoculated with wild-type B. elkanii were treated with methionine and ACC to assess the effects of the chemicals on the chlorosis. • Key Results: Chlorotic upper shoots of soybeans inoculated with wild-type B. elkanii had a lower methionine content and higher accumulation of the methionine precursors than those with the rhizobitoxine-deficient mutant. In addition, the foliar chlorosis was alleviated by the application of methionine. • Conclusions: Rhizobitoxine-induced chlorosis occurs in coincidence with methionine deficiency as a result of cystathione-β-lyase inhibition during methionine biosynthesis.

Original languageEnglish
Pages (from-to)55-59
Number of pages5
JournalAnnals of botany
Volume100
Issue number1
DOIs
Publication statusPublished - 2007 Jul

Keywords

  • Bradyrhizobium elkanii
  • Chlorosis
  • Glycine max
  • Methionine
  • Nodulation
  • Rhizobitoxine
  • Soybean

ASJC Scopus subject areas

  • Plant Science

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