Original Paper

World Journal of Microbiology and Biotechnology

, Volume 27, Issue 9, pp 2071-2079

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

2,4-Diacetylphloroglucinol suppresses zoosporogenesis and impairs motility of Peronosporomycete zoospores

  • M. Tofazzal IslamAffiliated withDivision of Plant Pathology and Plant Protection, University of GöttingenDepartment of Biotechnology, Bangabandhu Sheikh Mujibur Rahman Agricultural University Email author 
  • , Andreas von TiedemannAffiliated withDivision of Plant Pathology and Plant Protection, University of Göttingen


2,4-Diacetylphloroglucinol (DAPG) produced by Pseudomonas fluorescens, shows toxicity to many microorganisms including fungi, bacteria, and peronosporomycetes. Zoosporogenesis and motility of zoospores are critical for a complete disease cycle and pathogenicity of the peronosporomycete phytopathogens. The aim of this study was to test the effects of DAPG and its derivatives on zoosporogenesis and motility of zoospores of a downy mildew pathogen, Plasmopara viticola, and a damping-off pathogen, Aphanomyces cochlioides. In both cases, DAPG inhibited zoosporogenesis (5 μg/ml) and the motility of zoospores (10 μg/ml) in a dose-dependent manner. Generally, zoospores became immotile shortly after exposure to DAPG followed by lysis. However, a fraction of DAPG treated A. cochlioides zoospores formed round cystospores instead of lysis and then germinated with excessively-branched germ tubes. All derivatives of DAPG had similar inhibitory activities but at varying doses. Among them, 2,4-dipropylphloroglucinol exerted the highest inhibitory activity against both zoosporogenesis and motility of zoospores. This revealed that the degree of hydrogen atoms substitution in the benzene ring by acyl groups and the length of substituted acyl groups were related to the level of bioactivity. This is the first report of inhibitory activities of DAPG and its derivatives against zoosporogenesis and motility of zoospores of two important peronosporomycete phytopathogens.


Zoosporogenesis 2,4-Dipropylphloroglucinol Oomycetes Zoosporicides Plasmopara viticola Aphanomyces cochlioides