Spatial and temporal dynamics of bacterial community under elevated warming in field-grown wheat

Soil microbiome plays a crucial role in plant growth and productivity. However, the impact of climate changes on soil microbiome of agricultural ecosystems is less investigated. Here we utilized a long-term field warming experiment to investigate the effects of ambient (control) and elevated soil warming (+1.5 ?) on microbial activity and community composition at spatial (root, rhizosphere and bulk soil) and temporal (tillering, jointing and ripening stages of plant) scales in the field-grown wheat (Triticum aestivum L.). The root organic carbon (ROC), organic acids (OAs) in ROC and dissolved organic carbon (DOC) and microbial activity in rhizosphere soil were quantified together with determination of bacterial community structure by 16S rRNA gene sequencing. Rhizosphere ROC, DOC, and microbial activity were increased by soil warming and varied considerably across wheat growth stages. The microbial phyla such as Actinobacteria and Firmicutes shifted considerably in response to warming. Moreover, the abundance of genera involved in plant growth promotion such as Pseudomonas and Bacillus increased in root and rhizosphere under warming, and correlated significantly with oxalic, fumaric, malic, and with citric acid levels, respectively. Overall, our results indicate that soil warming along with root proximity and plant growth status drive changes in the bacterial diversity and community structure in the wheat root zone. These results imply that climate warming may indirectly affect soil microbial responses by altering microbial activity, diversity and community structure via root carbon exudation.