Response of rhizosphere bacterial community structure to drought stress in cucumber seedlings
[Objective]The study aimed to understand the response of rhizosphere bacterial community structure and function to drought stress in cucumber seedlings.[Method]Potted water control method was used to set up drought treatment D and normal treatment N,and the rhizo-sphere bacteria community structure and diversity in cucumber seedlings were determined by Illumina NovaSeq sequencing.[Result]The contents of chlorophyll and soluble sugar in treatment(N)were 2.440 and 10.380 mg/g,respectively,which were significantly higher than that of drought treatment(D),which was 1.547 and 8.356 mg/g(P＜0.05).The contents of proline and malondialdehyde in treatment D was 51.807 μg/g and 54.848 mol/g,respectively,which were significantly higher than those of treatment N(32.628 μg/g and 29.005 mol/g).The root activity of treatment N was 32.670 μg/(g·h),which was significantly higher than that of treatment D with 20.714 µg/(g·h).Superoxide dismutase(SOD)content of treatment N was 324.826 U/g,which was significantly lower than that of treatment D with 578.363 U/g.In the rhizosphere bacterial community of cucumber seedlings,the top five in abundance at the taxonomic level were Pro-teobacteria,Gemmatimonadota,Bacteroidota,Acidobacteriota and Actinobacteriota.There was no significant difference among treatments inα diversity index(Chao1,Shannon,Simpson).But PCoA analysis showed that there was significant difference in bacterial community struc-ture between the two treatments.Comparing to treatment D,Gemmatimonadota of treatment N was obviously up-regulated,while Bacteroidota and Firmicutes were obviously down-regulated(P＜0.05).LEfSe results showed that beneficial bacteria such as Muribaculaceae,Clostridia,Bacilli,etc.,which mainly belonging to Bacteroidota and Firmicutes,were significantly enriched in treatment D.The functional analysis of rhizosphere bacterial community showed that the abundance of RNA processing and modification,chromatin structure and dynamics,tran-scription,amino acid transport and metabolism,carbohydrate transport and metabolism and other related functions of treatment D significant-ly increased.Furthermore the synthetic pathway related to secondary metabolites such as thiamine and the degradation metabolic pathway dominated by sugars and amino acids were up-regulated.[Conclusion]Drought stress had significant impact on the rhizosphere bacterial com-munity structure of cucumber seedlings,which promoted the significant enrichment of beneficial microorganisms in rhizosphere soil,mainly Bacteroides and Sclerotinia,inducing and promoting the life activities of bacterial community,and significantly increased the abundance of secondary metabolites related to thiamine and degradation metabolic pathways mainly composed of sugars and amino acids.It was expected to provide new ideas for exploring the interaction mechanism of beneficial bacteria in soil that might have a positive impact on cucumber seed-lings growth under drought stress.
NETL
NSTL
万方数据
