| Summary: | Potato cultivars susceptible to common scab were previously reported to harbor five to six times more abundant pathogenic Streptomyces spp. in the rhizosphere soils compared with tolerant cultivars. It is still unclear if the diversity of soil bacterial communities is related to the abundance of pathogenic Streptomyces spp. This study evaluated the effects of potato cultivar on the diversity of bacterial communities in three spatial locations (soil located close to the plant [SCP], in the rhizosphere soil [RS], and in the geocaulosphere soil [GS]) in 2013 and 2014. Common scab tolerant (Goldrush and Hindenburg) and susceptible cultivars (Green Mountain and Agria) were planted in a field infested with pathogenic Streptomyces spp. causing common scab. The β-diversity of the bacterial community was significantly different between years and on dates within each year according to a permutational multivariate analysis of variance. The β-diversity also varied significantly among spatial locations (i.e., SCP, RS, and GS), probably due to changes in soil properties, but did not change significantly among potato cultivars. The architecture of the bacterial network in RS in 2014 was more complex compared with 2013 with a 2.5-fold increase in the number of bacteria included according to a co-occurrence analysis. These results indicated that the soil bacterial community diversity changed temporally and spatially. However, bacterial community diversity and richness were not affected by potato cultivar, suggesting that there were no relationships between bacterial community diversity or richness and the abundance of pathogenic Streptomyces spp.
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