Inhibition of uredospore germination and germ tube growth by inhibitors of polyamine metabolism in Uromyces phaseoli L

• Published in: Plant and cell physiology 1989-01, Vol.30 (1), p.37-41
• Main Authors: Rajam, M.V. (University of Delhi, New Delhi (India)), Weinstein, L.H, Galston, A.W
• Format: Article
• Language: English
• Subjects: AMINAS; AMINE; AMINES; ANTIMETABOLITE; ANTIMETABOLITES; ANTIMETABOLITOS; ARGININA; ARGININE; Biological and medical sciences; ESPORAS; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Germination and dormancy; GERMINATION INHIBITORS; INHIBIDORES DE LA GERMINACION; INHIBITEUR DE GERMINATION; METABOLISME DE L'AZOTE; METABOLISMO DEL NITROGENO; NITROGEN METABOLISM; ORNITHINE; ORNITINA; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Phaseolus vulgaris; Phytopathology. Animal pests. Plant and forest protection; Plant physiology and development; Polyamine; SPORE; SPORES; Uredospore germination; UROMYCES; Uromyces phaseoli; α-Difluoromethylarginine; α-Difluoromethylornithine
• ISSN: 0032-0781; 1471-9053; 1471-9053; 0032-0781
• DOI: 10.1093/oxfordjournals.pcp.a077714

We have studied the effects of two polyamine biosynthetic inhibitors, α-difluoromethylor-nithine (DFMO) and α-difluoromethylarginine (DFMA), and of polyamines (PAs), alone and in combination on uredospore germination and germ tube growth in Uromyces phaseoli L, race O. Both the inhibitors at concentrations 0.01, 0.1 and 1.0 mM produce successively inhibition of uredospore germination in vitro. The inhibitors also delay the timing of spore germination for 15–30 min and restrict germ tube elongation. Stimulation of spore germination and germ tube growth was noticed in cultures containing PAs (putrescine or spermidine) alone, while cultures fortified with inhibitor plus PA resulted in a partial reversion of the inhibitory effect, suggesting that PAs may be required for normal germination and outgrowth of fungal spores. Spore germination was completely inhibited on the surface of unifoliolate bean leaves treated with 0.5 mM or higher DFMO 1 d before inoculation with pathogen, while DFMO treated 1 d after inoculation showed greater damage of uredosporelings. In contrast, DFMA confers no effect even at 5 mM. Spores collected from bean plants given a pre- and post-inoculatory treatments with DFMO and DFMA show no significant differences in germination and pathogenicity, however, the higher doses caused significant decrease.