Infection-inhibition activity of avenacin saponins against the fungal pathogens Blumeria graminis f. sp. hordei, Bipolaris oryzae, and Magnaporthe oryzae

Triterpenoid saponins are sugar-modified triterpene derivatives. Cereals and other grasses are generally deficient in these secondary metabolites with the exception of oat. Oat accumulates antimicrobial triterpenoid saponins in its roots. These oat-root-derived compounds, called avenacins, confer broad-spectrum resistance to soil-borne pathogens. Here, we tested the effect of avenacins on the development of infection structures of fungal pathogens Blumeria graminis f. sp. hordei and Bipolaris oryzae and Magnaporthe oryzae. We show that avenacins are able to inhibit the infection process of these phytopathogens on plant hosts.