Enoch Narh Kudjordjie, Willem Desmedt, Tina Kyndt, Mogens Nicolaisen, Reuben J Peters, Mette Vesterg��rd
Rice synthesises diterpenoid phytoalexins (DPs) which are known to operate in defence against foliar microbial pathogens and the root-knot nematode Meloidogyne graminicola. Here, we examined the role of DPs in shaping rice-associated root microbiomes in nematode-infested field soil. Further, we assessed how DPs affect interactions between the root microbiomes and M. graminicola. We used 16S and ITS2 rRNA gene amplicon analysis to characterise the root- and rhizosphere-associated microbiomes of DP knock-out rice mutants and their wild-type parental line, at an early (17���days) and late (28���days) stage of plant development in field soil. Disruption of DP synthesis resulted in distinct changes in the composition and structure of microbial communities both relative to the parental/wild-type line but also between individual mutants, indicating specificity in DP-microbe interactions. Moreover, the abundance of nematode-suppressive microbial taxa, including Streptomyces, Stenotrophomonas and Enterobacter was negatively correlated with that of Meloidogyne. Differential enrichment of microbial taxa in the roots of rice DP knock-out mutants versus wild-type suggests that DPs modulate specific taxa in the rice root microbiome. These findings indicate a role for DPs in plant-microbiome assembly and nematode interactions, further underscoring the potential of leveraging phytoalexins for sustainable management of crop diseases.
