LAUSR

Soil-borne pathogens destabilize the yields of Triticeae crops, including barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.). Although genetic resistance derived from relatives of these species has been utilized to prevent rust diseases (i.e. in the wheat-rye 1BL-1RS translocation line), research on resistance against soil-borne pathogens remains limited. Here, we performed field trials using 76 genotypes representing 28 Hordeum, six Triticum, and two Aegilops species to examine resistance against three soil-borne bymoviruses: barley yellow mosaic virus (BaYMV), barley mild mosaic virus (BaMMV), and wheat yellow mosaic virus (WYMV). We also performed greenhouse tests using the soil-borne fungal pathogen Fusarium pseudograminearum, which causes Fusarium crown rot (FCR). Using RT-PCR, we detected BaMMV and BaYMV in several Hordeum species, whereas WYMV induced systemic infection in the Triticum and Aegilops species. The identification of FCR susceptibility in all species examined suggests that F. pseudograminearum is a facultative fungal pathogen in Triticeae. Intra-species variation in FCR disease severity was observed for several species, pointing to the possibility of exploring host resistance mechanisms. Therefore, by unlocking the host specificity of four soil-borne pathogens in Hordeum species and their relatives, we obtained insights for the further exploration of wild sources of soil-borne pathogen resistance for future wheat and barley improvement programs.