Potato Root-Associated Bacteria: Site/Cultivar Differences and Associations With Tuber Yield and Quality.

Potatoes are the fourth most important food crop in the world with consumption increasing worldwide, especially in developing nations.  Breeding programs focus on potato quality for disease resistance and culinary quality; in addition, some programs are beginning to focus on anti-cancer activity of potatoes.  Studies concentrating on the bacterial inhabitants of potato soil and roots find that communities are highly influenced by soil edaphic features, and within a site microbial communities are influenced by the specific potato clone.  The aim of our study was to describe the variability in the bacterial root-associated community due to site versus clone, and whether an underlying core bacterial community exists which might benefit the quality of the potato crop. Using 454 sequencing, we examined root-associated microbial communities of 18 potato clones grown in three states (CA, CO, TX), as well as the bulk soil.  Variance analysis using perMANONVA attributed 45.4% and 24.1% of the community variability to site and clone effects, respectively.  sPLS regression techniques were used to identify root-associated microbes correlated with tuber and yield.  For example, 22 bacterial OTUs were positively correlated with cultivar-specific tuber yields; and the majority of these belong to the order Rhizobiales with 5 of the top 13 predictors belonging to the genus Devosia.  Additional associations between tuber quality characteristics and the root microbial community will also be discussed.