Antifungal effects of hydrogen peroxide and peroxidase on spore germination and mycelial growth ofPseudocercosporaspecies

Abstract

Spore germination in Pseudocercospora abelmoschi (Ell. & Ev.) Deighton USDB1312 and Pseudocercospora cruenta (Sacc.) Deighton USDB1313, pathogens of Hibiscus esculentus L. and Vigna sinensis ssp. sesquipedalis (L.) van Eseltine, was significantly inhibited when incubated with different levels of hydrogen peroxide (0.03 × 10-5- 4.59 × 10-5M H2O2) and 1-100 µg/mL peroxidase (equivalent to 1.06-106 enzyme units). Significant reduction in mycelial growth was also observed in both fungi at different levels of H2O2(0.03 × 10-5- 7.71 × 10-5M) and 1-1000 µg/mL peroxidase. The spores and mycelium of P. cruenta USDB1313 could tolerate higher levels of H2O2(0.03 × 10-5- 2.61 × 10-5M) compared with that of P. abelmoschi USDB1312. The effects of peroxidase on spore germination and mycelial growth were similar in both P. abelmoschi and P. cruenta isolates. Spore germination and mycelial growth were inhibited significantly at higher levels of peroxidase. The results of this study complemented earlier field observations on the resistance or susceptibility of H. esculentus and V. sinensis ssp. sesquipedalis to both fungi.Key words: hydrogen peroxide, peroxidase, Pseudocercospora spp.