Identification of phenylamide phytoalexins and characterization of inducible phenylamide metabolism in wheat

Naoki Ube, Daiyu Harada, Yuhka Katsuyama, Kumiko Osaki-Oka, Takuji Tonooka, Kotomi Ueno, Shin Taketa, Atsushi Ishihara

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Changes in specialized metabolites were analyzed in wheat leaves inoculated with Bipolaris sorokiniana, the causal agent of spot blotch of Poaceae species. HPLC analysis detected the accumulation of six compounds in B. sorokiniana-infected leaves. Of these, we purified two compounds by silica gel and ODS column chromatography and preparative HPLC, and identified them as cinnamic acid amides, N-cinnamoyl-9-hydroxy-8-oxotryptamine and N-cinnamoyl-8-oxotryptamine, by spectroscopic analyses. The remaining four compounds were predicted to be p-coumaric acid amides of hydroxyputrescine, hydroxyagmatine, hydroxydehydroagmatine, and agmatine by mass spectrometry. The accumulation of two cinnamic acid amides was also induced by Fusarium graminearum infection, and by treatment with CuCl2, jasmonic acid, and isopentenyladenine. Antifungal activity of these amides was shown by inhibition of conidial germination and germ tube elongation of F. graminearum and Alternaria brassicicola, indicating that they act as phytoalexins. The accumulation of these amides also detected in barley leaves treated with CuCl2. We examined the accumulation of 25 phenylamides in B. sorokiniana-infected wheat leaves using LC-MS/MS. Hydroxycinnamic acid amides of tryptamine, serotonin, putrescine, and agmatine, were induced after infection with B. sorokiniana. Thus, the induced accumulation of two groups of phenylamides, cinnamic acid amides with indole amines, and p-coumaric acid amides with putrescine and agmatine related amines, represents a major metabolic response of wheat to pathogen infection.

Original languageEnglish
Article number112098
JournalPhytochemistry
Volume167
DOIs
Publication statusPublished - Nov 2019

Keywords

  • Bipolaris sorokiniana
  • Fusarium graminearum
  • Phenylamide
  • Phytoalexin
  • Poaceae
  • Triticum aestivum

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Plant Science
  • Horticulture

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