Effect of Pythium spp. and glyphosate on phytoalexin production and exudation by bean ( Phaseolus vulgaris L.) roots grown in different media

• Published in: Physiological and molecular plant pathology Vol. 47; no. 6; pp. 391 - 405
• Main Authors: Liu, L., Punja, Z.K., Rahe, J.E.
• Format: Journal Article
• Language: English
• Published: London Elsevier India Pvt Ltd 01-12-1995; Elsevier
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; NA, nutrient agar; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; PDA, potato dextrose agar; Phytopathology. Animal pests. Plant and forest protection; PIF, phaseonllinisolflavan; NA, nutrient agar; PIF, phaseonllinisolflavan; PDA, potato dextrose agar; Plant pathogen; Pythium; Phycomycetes; Biochemistry; Glyphosate; Fungi; Disease resistance; Dicotyledones; Angiospermae; Production; Qualitative analysis; Elicitation; Inhibition; Species; Thallophyta; Quantitative analysis; Culture medium; Pathophysiology; Root; Secretion; Host agent relation; Synthetic inhibitor; Metabolism; Defense; Herbicide; Biological compound; Grain legume; Pythium ultimum; Leguminosae; Vegetable crop; Phaseolus vulgaris; Phytoalexin; Spermatophyta; Exudation; Biological accumulation; Phaseollin
• ISSN: 0885-5765; 1096-1178
• DOI: 10.1006/pmpp.1995.1067

Kievitone, phaseollinisoflavan and phaseollin were detected in roots of bean seedlings (
Phaseolus vulgaris L.) grown in natural soil. Comparison of phytoalexin production by roots grown in different media indicated that these phytoalexins were probably induced by microorganisms in soil. The influence of common root rot pathogens of bean,
Pythium spp., on phytoalexin production was determined.
Pythium ultimum elicited kievitone, phaseollinisoflavan and phaseollin in roots grown in sterilized silica sand.
P. sylvaticum induced only kievitone and phaseollin in the same growth medium. Glyphosate did not significantly affect the accumulation of phytoalexins within 3 days. However, by day 5, significantly more phaseollin was detected in the roots of
Pythium inoculated plants treated with glyphosate than in
Pythium inoculated plants not treated with glyphosate. In a hydroponic system, both
Pythium spp. elicited accumulation of kievitone and phaseollin in root tissue, and both phytoalexins were exuded into the bathing solution. Glyphosate application did not significantly affect accumulation or exudation of phytoalexins by bean roots in the hydroponic system. The results from this study illustrate the nature and extent of phytoalexin production by bean roots in the absence and presence of microbes.