Endophyte-Mediated Resistance in Tomato to Fusarium oxysporum Is Independent of ET, JA, and SA

Root endophytes can confer resistance against plant pathogens by direct antagonism or via the host by triggering induced resistance. The latter response typically relies on jasmonic acid (JA)/ethylene (ET)-depended signaling pathways, but can also be triggered via salicylic acid (SA)-dependent signaling pathways. Here, we set out to determine if endophyte-mediated resistance (EMR), conferred by the Fusarium endophyte Fo47, against Fusarium wilt disease in tomato is mediated via SA, ET or JA. To test the contribution of SA, ET, and JA in EMR we performed bioassays with Fo47 and Fusarium oxysporum f. sp. lycopersici in tomato plants impaired in SA accumulation (NahG), JA biosynthesis (def1) or ET-production (ACD) and -sensing (Nr). We observed that the colonization pattern of Fo47 in stems of wildtype plants was indistinguishable from that of the hormone mutants. Surprisingly, EMR was not compromised in the lines affected in JA, ET, or SA signaling. The independence of EMR on SA, JA, and ET implies that this induced resistance-response against Fusarium wilt disease is distinct from the classical Induced Systemic Resistance (ISR) response, providing exciting possibilities for control of wilt diseases independent of conventional defense pathways.

Wongia gen. nov. (Papulosaceae, Sordariomycetes), a new generic name for two root-infecting fungi from Australia

The classification of two root-infecting fungi, Magnaporthe garrettii and M. griffinii, was examined by phylogenetic analysis of multiple gene sequences. This analysis demonstrated that M. garrettii and M. griffinii were sister species that formed a well-supported separate clade in Papulosaceae (Diaporthomycetidae, Sordariomycetes), which clusters outside of the Magnaporthales. Wongia gen. nov, is established to accommodate these two species which are not closely related to other species classified in Magnaporthe nor to other genera, including Nakataea, Magnaporthiopsis and Pyricularia, which all now contain other species once classified in Magnaporthe.