Induced gene expression in wheat seedlings treated with a crude extract of Agapanthus africanus L. prior to leaf rust infection

Abstract

It was previously shown that a crude extract of Agapanthus africanus L. (Hoffman), applied as a foliar spray to wheat (Triticum aestivum L.) seedlings, significantly increased the in vitro activities of three pathogenesis related (PR) proteins (β-1,3-glucanase, chitinase and peroxidase). This was the case in both susceptible and resistant wheat lines whether the plants were uninfected or infected with leaf rust (Puccinia triticina). The aim of this study was to determine the influence of the A. africanus extract on both the intercellular PR-protein profile and PR gene expression in leaf rust infected wheat lines. Pre-treatment of infected resistant and susceptible wheat with the extract led to increased β-1,3-glucanase levels that were higher as compared to the untreated controls. Similarly, treatment with the extract led to greater expression of both the PR3 and PR9 genes in infected resistant and susceptible seedlings as compared to the controls. This is also applied to a retrotransposon protein encoding gene whose expression was strongly induced following extract treatment. The induced expression of all these defence-related genes suggests that the crude A. africanus extract has the ability to prime the resistance response of wheat prior to leaf rust infection. Key words: Wheat leaf rust, induced resistance, priming, gene expression, immunoblotting, crude Agapanthus africanus extract.