Graduate Student Researcher University of California Riverside Riverside, California
Plant-parasitic nematodes are pests that devastate yields of economically important crops. Yet, plant-nematode interactions are often overlooked in studies of plant-based species interactions. Asian rice, Oryza sativa, is particularly affected by root-knot nematodes (RKNs), including Meloidogyne graminicola and M. incognita. These crop pests are limiting factors and major threats to rice production and can account for up to 80% of yield losses for rice grown in a diversity of agroecosystems. Foundational research of the mechanisms underlaying these interactions is essential for developing tools and novel strategies for Meloidogyne management in this crop that is critical to global food security. Studies that have leveraged an evolutionary systems biology approach demonstrated its ability to predict molecular mechanisms that elucidate genotype-phenotype relationships. Our reanalysis of transcriptomic data from a field-based systems biology study revealed genes and pathways potentially involved in rice defense responses to RKNs. We identified that differentially expressed genes in rice roots responding to M. graminicola were significantly enriched within fitness-linked modules of a gene co-expression network constructed from a rice diversity panel. Key plant defense-related pathways and processes enriched in these modules include: (1) the phenylpropanoid pathway, which leads to a variety of defense-related products (e.g. phytohormones, phytoalexins, flavonoids, lignin, waxes); (2) plant-pathogen interaction genes like peroxidases and chitinases; and (3) secondary metabolite pathways such as diterpenoids. The evolutionary systems biology framework highlighted defense-related mechanisms and identified gene targets for further investigation. Our next steps will be to begin functional tests of top candidates using targeted genetic approaches in rice.