Colletotrichum coccodes and thidiazuron alter specific peroxidase activities in velvetleaf ( Abutilon theophrasti)

• Published in: Physiological and molecular plant pathology Vol. 43; no. 1; pp. 47 - 56
• Main Authors: Nickerson, R.G., Tworkoski, T.J., Luster, D.G.
• Format: Journal Article
• Language: English
• Published: London Elsevier India Pvt Ltd 01.07.1993; Elsevier
• Subjects: Agronomy. Soil science and plant productions; ai, active ingredient; Biological and medical sciences; Biological control and other methods; Fundamental and applied biological sciences. Psychology; IEF, isoelectric focusing; Parasitic plants. Weeds; Phytopathology. Animal pests. Plant and forest protection; pI, isoelectric point; TDZ, thidiazuron; Weeds; TDZ, thidiazuron; IEF, isoelectric focusing; pI, isoelectric point; ai, active ingredient; Malvaceae; Abutilon theophrasti; Agricultural chemical product; Plant pathogen; Plant juvenile growth stage; Biological agent; Alteration; Biochemistry; Thiadiazole derivatives; Synergism; Fungi; Enzymatic activity; Dicotyledones; Angiospermae; Plant growth substance; Ureas; Peroxidase; Fungi Imperfecti; Integrated pest management; Thallophyta; Weed control; Weed; Enzyme; Biochemical compound; Colletotrichum coccodes; Cytokinin; Fundamental mechanism; Peroxidases; Spermatophyta; Oxidoreductases
• ISSN: 0885-5765; 1096-1178
• DOI: 10.1006/pmpp.1993.1039

The height and biomass of velvetleaf ( Abutilon theophrasti), were inhibited by treatment of young seedlings with the fungal pathogen Colletotrichum coccodes or with the growth regulator thidiazuron (TDZ). Applied simultaneously, these two agents synergistically reduced velvetleaf height and biomass. The use of two different peroxidase substrates, guaiacol and o-dianisidine, detected different peroxidase isoform activities. This study identified C. coccodes- and TDZ-induced changes in peroxidase activity and isoform pattern. Treatment with C. coccodes increased soluble peroxidase activity as measured spectrophotometrically with the peroxidase substrate guaiacol. TDZ treatment had no observed effect on guaiacol-reactive soluble peroxidase activity. Isoelectric focusing analysis of peroxidase isoform activity using o -dianisidine as a substrate demonstrated that both TDZ and C. coccodes caused changes in the temporal expression and activity of specific anionic isoforms. TDZ enhanced the activity of a pI 4·26 isoform while C. coccodes enhanced the activity of a pI 4·03 isoform. The combination of TDZ and C. coccodes caused a simultaneous and rapid stimulation of both these isoforms. Based on these observations, and previously published reports of disease symptomatology, we propose that the increase in guaiacol-reactive soluble peroxidase activity represents a peroxidase-associated defence response, and that the increased activity of the pI 4·03 and 4·26 isoforms is associated with the inhibition of growth. The rapid stimulation of both isoforms following the combined treatment may account for the synergistic inhibition of growth.