Effects of drought stress on rhizosphere soil bacterial community of potato throughout the reproductive period

【Objective】 To explore the effects of drought stress on rhizosphere soil bacterial community during the whole life cycle of potato,to reveal the response mechanism of potato rhizosphere soil bacteria to drought stress,and to analyze the interactions between rhizosphere soil nutrients and rhizosphere bacterial community,so as to provide theoretical basis for the development and utilization of rhizosphere soil bacterial resources and improvement of the structure of rhizosphere soil bacterial community through the regulation of soil nutrients and thus to improve the adaptability of potato to drought stress.【Method】 The potato variety Lishu 6 was used as the test material, and the drought treatment(D) and normal watering treatment(CK) were set up in a potted water control test, and 16S rRNA was used for high-throughput sequencing to analyze the structural changes of the rhizosphere soil bacterial community at the seedling, tuber formation, starch accumulation and maturity stages of potato. The relationships between soil environmental factors and rhizosphere bacterial communities were analyzed using redundancy analysis(RDA) and Mantel test.【Result】 Drought stress affects soil physico-chemical properties differently at different fertility periods,drought stress did not significantly affect the number of effective tags, OTUs and the number of annotated phyla, orders, families and species of potato rhizosphere soil bacterial populations during a given reproductive period(P>0.05,the same below), and that drought stress significantly reduced the number of annotated phyla during tuber formation(P<0.05,the same below),and significantly increased the number of annotated genera during starch accumulation compared with the control. α diversity analysis showed that the Simpson, Chao1 and Shannon indexes were not significantly different from the control during the whole growing period of potato compared to normal watering, while the ACE index was significantly higher than the normal watering group at the seedling, tuber formation and maturity stages, with an inverse trend at the starch accumulation stage. Proteobacteria, Acidobacteriota, Actinobacteriota, Gemmatimonadota, Chloroflexi, Bacteroidota and Myxococcota were the dominant phylum in the rhizosphere soil during the whole growing period under drought stress and normal watering treatment; RDA and Mantel test analysis showed that soil conductivity, organic carbon and pH were the key factors affecting the composition of soil bacterial communities in potato roots.【Conclusion】 Drought stress significantly affects the relative abundance of rhizosphere soil bacteria throughout the potato reproductive period, increases the abundance and evenness of rhizosphere soil bacterial communities at seedling, tuber formation and maturity stages. Potato rhizosphere soil pH, conductivity and organic carbon content are key factors affecting the structure of the potato rhizosphere soil bacterial community.