Bacterial communities associated with food-quality winter pea cultivars grown in Pacific Northwest soils

Abstract Background and aims Breeding legumes for improved yield and seed quality, coupled with extensive use of fertilization may disrupt the ability of modern cultivars to interact with the native soil microbiome. Autumn-sown food-quality winter pea (WP) represent a new crop in the Pacific Northwest (PNW). However, little is known about the ability of these cultivars to establish associations with bacteria native to PNW soils. Methods 16S rRNA amplicon sequencing was used to evaluate soil, root and nodule microbiomes associated with four WP cultivars in diverse locations across Washington state with the goal to better understand the interaction occurring between WP cultivars and bacterial communities native to PNW soils. Results Root and nodule microbiomes were affected by the sampling event, while plant genotype only affected nodule microbiome. A diverse population of native rhizobia colonized WP roots, while a smaller subset of these bacteria colonized WP nodules. Three rhizobial ASVs had relatively low abundance in the soils but were dominant in nodule-associated microbiome regardless of the variation of soil parameters between locations, indicating their strong attraction to host-plant nodules. Several non-rhizobial taxa were apparently enriched in nodules. However, in-depth study of legume root and nodule microbiome is required to better understand interactions within this complex phytobiome. Conclusion WP cultivars can form nodules in PNS soils in fall, but environmental factors have a strong effect on this process. While the complementation of legume nodule microbiome with root-associated microbiome analysis might be a useful tool, studies focusing on mature nodules with increased depth of sequencing might provide a better resolution of nodule-specific residents.