Differences among Soil-Inhabiting Microbial Communities in Poa annua Turf throughout the Growing Season

There is increasing interest in understanding plant-associated microbial communities and their impact on plant health. However, research has been limited to major agronomic systems and little is known about the resident microorganisms in economically important specialty crops, such as turfgrass. In this study, we generated a community-wide inventory of the archaea and bacteria that inhabit the soil of Poa annua L. putting green turf at five time points over a 1-yr period. Next-generation sequencing of the nuclear ribosomal DNA 16S revealed 1.5 x 10(5) unique operational taxonomic units from 25 pooled soil samples. Seventeen archaeal taxa were identified at the species level, 53% of which were members of the Crenarchaeota. Proteobacteria was the most abundant bacterial phylum, comprising 36% of the 442 taxa present. Distance analysis and analysis of similarities revealed that the archaeal and bacterial communities clustered according to sample date, with samples collected during warm months grouping separately from those collected during cool months. Clustering was less distinct when plotted using detrended correspondence analysis. These data indicate that microbial community structure varied throughout the growing season, possibly due to seasonal changes in temperature and/or other environmental factors. This research also shows that P. annua putting green turf supports a diverse microbial community despite management practices that include frequent pesticide applications.