Acibenzolar-S-methyl-induced alteration of defence gene expression and enzyme activity in cotton infected with Fusarium oxysporum f. sp. vasinfectum

Abstract

The effect of acibenzolar-S-methyl (ASM) applied in the form of Bion ® as a seed soak or a foliar spray, on transcript accumulation of six defence related genes, and activities of four defence related enzymes, was assessed after cotton was inoculated with Fusarium oxysporum f. sp. vasinfectum ( Fov). Significant upregulation of chitinase class I, peroxidase, and β-1, 3-glucanase transcripts occurred in the Bion ® seed soak treatment with Fov inoculation compared to all other treatments. Bion ® alone did not significantly increase transcripts compared with water control treatments in the majority of cases. Phenylalanine ammonia lyase transcript in Bion ® treated plants following fungal inoculation was greater than in the respective Bion ® alone treatments, and osmotin-like protein transcript was significantly greater in inoculated plants sprayed with Bion ® than in all other treatments. Transcripts of 4-coumarate-CoA ligase-like protein were generally lower than for all other genes, and significant upregulation compared with water control occurred in extracts from Fov inoculated plants receiving no Bion ® treatment, and Fov inoculated plants cultivated from Bion ® treated seed. The greatest increases in chitinase, β-1, 3-glucanase and peroxidase activity occurred in root and shoot tissue from Bion ® seed treated material inoculated with Fov. Bion ® treatment alone did not consistently enhance enzyme activities above those measured in water treated controls. Polyphenol oxidase activities were enhanced by various Bion ® or Fov treatments at 3 days after inoculation only.