Response of rhizosphere soil bacteria to temperature changes in Caragana jubata from different elevation provenances

Rhizosphere microorganisms are closely related to the ecological adaptations of plants. Studying the response of plant rhizosphere microorganisms to environmental changes can help provide a better understanding of the ecological adaptation of plants. In this study, the differences in rhizosphere soil bacterial diversity and community structure as well as the root functional traits of Caragana jubata at different elevations (A₁: 2 950 m and A₂: 3 530 m) were comparatively analyzed under different temperature conditions (T₁: 10 ℃ and T₂: 25 ℃). The results showed that temperature change significantly affected the Chao1 index (P < 0.05) of C. jubata from A₁ provenance but had a weak effect on the Chao1 and Shannon indexes of C. jubata from A₂ provenance. Principal coordinate analysis showed that temperature change significantly affected the rhizosphere soil community structure (r = 0.53, P < 0.05) of the provenance from A₂. Compared with T₂, T₁ significantly increased the relative abundance of Actinobacteria and Pseudomonas for the provenance at A₁ and increased the relative abundance of Kapabacteria, Cellvibrio, Glutamicibacter, Microbacterium, and Nocardia of C. jubata from A₂ provenance (P < 0.05). Meanwhile, temperature change significantly decreased the root surface area, number of root tips, mean root diameter, root volume, and root length of C. jubata from the A₁ provenance (P < 0.05) but only had a significant effect on the mean root diameter of C. jubata from A₂ provenance. In addition, Mantel test showed that the bacterial community structure of C. jubata from A₁ provenance was significantly affected by temperature, root length, and root mean diameter (P < 0.05) whereas that of C. jubata from A₂ provenance was significantly affected by temperature, root volume, root surface area, and root mean diameter (P < 0.05). In conclusion, the present study demonstrated that the rhizosphere bacterial diversity and community and root traits of different altitude provenances of C. jubata varied in their responses to temperature changes and that root traits had a strong impact on the variation of bacterial diversity and community.