Endophytic bacteria isolated from <i>Leptospermum scoparium</i> produce compounds that inhibit <i>Ilyonectria</i> and <i>Neofusicoccum</i> species <i>in vitro</i>

Abstract

Leptospermum scoparium JRForst et GForst var scoparium or m?nuka is a New Zealand indigenous shrub This shrub is valued for the essential oil and medicinal honey it produces that have antimicrobial properties International research has demonstrated that endophytic bacteria can either directly produce or modify metabolites in planta Therefore bacteria within the m?nuka endomicrobiome may also produce antimicrobial compounds A total of 192 endophytic bacteria were recovered from surface sterilised leaf stem and root tissue from three different sites These bacteria were assessed in dual culture assays against the grapevine pathogens Ilyonectria spp and Neofusicoccum spp Eleven and three endophytic bacteria showed ability to inhibit I liriodendri and N luteum respectively These endophytic bacteria produced both diffusible and volatile compounds that inhibited the pathogens Isolate W4R11 inhibited the growth of Ilyonectria spp by 4164 after 7 days incubation Isolate W1R33 could inhibit the faster growing Neofusicoccum spp by 2053 after 3 days incubation Microscopy showed that diffusible compound produced by isolate I1R21 caused hyphae and spore abnormality of Ilyonectria spp This study indicated that m?nuka can potentially provide a new source of microorganisms for use in sustainable agriculture