Antifungal proteins from seeds of Australian native plants and isolation of an antifungal peptide from Atriplex nummularia

Abstract

Extracts from seeds of 69 different species of plants mostly originating from Australia were screened for antifungal agents with activity against the plant pathogens, Fusarium oxysporum fsp. vasinfectum, Rhizoctonia solani, Thielaviopsis basicola, and Verticillium dahliae. Many seed extracts showed inhibitory activity against one or more of the fungi tested. High antifimgal activities were detected in the genera Archontophoenix, Atriplex, Alphitonia, Callistemon, and Dodonaea. Only the Atriplex seed extract was shown to contain a protease-sensitive antifungal activity. A 30 amino acid residue peptide (An1) was purified to homogeneity from the seeds of Atriplex nummularia and its in vitro activity against several fungal pathogens of plants was characterised. Amino acid sequence analysis revealed Anl to be homologous to the chitin-binding antimicrobial peptides of Amaranthus caudatus.