Actions of 6-pentyl-alpha-pyrone in controlling seedling blight incited by fusarium moniliforme and inducing defence responses in maize

Abstract

The antifungal metabolite 6-pentyl-alpha-pyrone (6PAP) exhibited phytotoxic effects on germination and elongation growth of coleoptiles when maize kernels were germinated on filter papers impregnated with 300 and 200 mg/l 6PAP, respectively. 6PAP severely retarded development of both roots and shoots of maize seedlings in nutrient solutions at increasing concentrations (200-300 mg/l). In contrast, under greenhouse conditions, 6PAP, applied as soil drenches, exhibited no phytotoxic effects. Soil drench applications of 6PAP 4 days before inoculation (dbi) with Fusarium moniliforme showed considerable seedling blight suppression and substantial plant growth promotion compared with the untreated control. In the presence of 200 mg/l 6PAP, both shoot and root developments were increased and higher dry weights were attained compared with the healthy control. To study the ability of 6PAP to induce the defence responses, the compound was applied on maize seedlings 2 dbi and the activities of peroxidase (PO), polyphenoloxidase (PPO) and β-1,3-glucanase in plant tissues were determined at two sampling times. Application of 6PAP on maize seedlings distinctly enhanced PO, PPO and β-1,3-glucanase activities in both shoot and root tissues compared with the untreated controls. Generally, 6PAP treatments induced higher activities of PO, PPO and β-1,3-glucanase in maize tissues than F. moniliforme infections. These results, however, provide the first evidence of the ability of 6PAP to control seedling blight disease incited by F. moniliforme in vivo and to induce defence responses in maize plants against the pathogen. © 2009 Blackwell Verlag GmbH.