The effects of polyamine biosynthesis inhibitors on mycelial growth, enzyme activity and polyamine levels in the oat-infecting fungus Pyrenophora avenae

Abstract

The fungus Pyrenophora avenae, an important pathogen of oat crops, was grown on solid and liquid media containing the polyamine b p t h e s i s inhibitors difluoromethylomithine (DFMO), methylglyoxal bdguanylhydrazone) (MGBG), ethylm@ylglyoxal bis(guanylhydraz0ne) (EMGBG) + / -polyamines. All of the compounds inhibited mycelial growth i f the fungus. MGBG and EMGBG were more effective than DFMO. The addition of putresine and spermidine almost completely prevented inhibition of mycelial growth by DFMO. However, no such effect was observed for inhibition by MGBG or EMGBG. Neither the inhibitors nor exogenous polyamines had any significant effect on the size of the fungal cells. DFMO and MGBG, alone and in combination, reduced the activity of omithine decarboxylase. Fungus grown in media containing EMGBG showed reduced activity of S adenosylmethionine decarboxylase. Putrescine snd spermidine concentrations decreased when the fungus was grown in media containing DFMO or DFMOlMGBG combined. MGBG.reduced spermidhe and spermine concentrations and EMGBG greatly reduced spermidine concentrations. AU of the compounds reduced the concentration of cadaverine, which is a significant component of P. auenae. The respiration rate of the fungus decreased when grown in media containing MGBG or DFMO/MGBG combined.

Biogenic Amines in Rhizobia and Legume Root Nodules

“…Following that historical study, the requirement was confirmed in many polyamine-auxotrophic mutants of Escherichia coli and Saccharomyces cerevisiae (153). Thereafter, numerous studies on the growth inhibition of phytopathogenic fungi (30,99,126,147,(165)(166)(167) or yeast (91,120) were conducted using specific inhibitors of polyamine biosynthesis. In most cases, the inhibition can be completely reversed by the addition of Put or Spd, confirming the essentiality of polyamines for the growth of fungal hyphae (125).…”

Endogenous polyamine content and metabolism in the ectomycorrhizal fungus Paxillus involutus

“…Yeasts, Neurospora crassa and Aspergillus nidulans (Tabor & Tabor, 1985) as well as some phytopathogenic fungi, especially rusts (Foster & Walters, 1990) do not have ADC, and synthesize putrescine by ODC only. However, other phytopathogenic fungi have active ADC (Khan & Minocha, 1989) and Zarb & Walters (1994b) gave evidences of ADC activity in Laccaria proxima.…”

Polyamines in Plants Infected by Citrus Exocortis Viroid or Treated with Silver Ions and Ethephon

“…The reaction mixture (total volume of 150 ,uL) contained 20 ,L of enzyme, 120 gL assay buffer, and 10 gL of 0.5% (w/v) FTC-casein.…”

“…Polyamines have been implicated in a range ofphysiological plant responses (20,22). The possible involvement of polyamines in the transduction of the viroid pathogenic signaling has also been hypothesized (14).…”