盐胁迫下配施钙肥对花生根际土壤细菌群落结构的影响

为了解不同生育时期盐胁迫下基施钙肥花生根际土壤微生物群落结构变化，以期通过改良盐碱土壤根际微生物环境来提高植物胁迫耐受性。采用盆栽试验设置不同盐胁迫强度及基施钙肥处理，以花生不同生育时期根际土壤为研究对象，通过构建细菌16S rRNA基因文库和高通量测序技术进行测序，并对测序结果进行生物信息学分析。结果表明：各处理土壤样本细菌物种多样性高且分布均匀，盐胁迫可提高花生根际微生物群落相对丰富度和多样性，并与生育时期有关;盐胁迫、生育时期和外源施钙各处理样本的优势菌纲、优势菌科及优势菌种相同，其优势菌纲均为放线菌纲（Actinobacteria）、α-变形菌纲（Alphaproteobacteria）、γ-变形杆菌纲（Gammaproteobacteria）、疣微菌纲（Verrucomicrobiae）、Saccharimonadia、芽单胞菌纲（Gemmatimonadetes）、拟杆菌纲（Bacteroidia）和酸杆菌纲（Acidobacteriia）等8种，优势菌科有norank_o__Saccharimonadales、鞘脂单胞菌科（Sphingo monadaceae）、芽单胞菌科(Gemmatimona daceae)、伯克氏菌科(Burkhold eriaceae)和norank_o__Gaiellales菌科等;盐胁迫和基施钙肥处理均能显著提高γ-变形杆菌纲（Gammaproteobacteria）和疣微菌纲（Verrucomicrobiae）丰度，并随生育时期的延长和盐胁迫强度增大更为明显，高盐胁迫下花针期和收获期两菌纲丰度分别是其对照的1.2、1.8倍和1.6、1.5倍，但盐胁迫下基施钙肥处理可使放线菌纲（Actinobacteria）、Saccharimonadia菌纲相对丰度明显降低，并随盐胁迫强度提高相对丰度降幅明显，且开花下针期降幅较大；噬几丁质菌科（Chitinophagaceae）和丰佑菌科（Opitutaceae）的相对丰度受盐胁迫强度和生长阶段影响显著，并随盐胁迫强度升高而显著提高；生长盛期和基施钙肥处理的氨基酸代谢、能量代谢、辅助因子和维生素的代谢和核苷酸代谢等功能基因相对丰度显著提高；盐胁迫严重抑制花生籽仁发育，产量明显降低，高盐胁迫使荚果产量降低40%～50%。

Effects of calcium fertilizer application on peanut rhizosphere bacterial community structure under salt stress

To assess the peanut rhizosphere bacteria community structure in response to the basal application of calcium fertilizer under salt stress at different development stages and enhance plant stress tolerance by improving the rhizosphere microbial environment of saline|alkali soil, a pot experiment was set up with different salt concentrations. The rhizosphere soils of different growth stages were used to extract DNA for constructing bacterial 16S rRNA gene library, and then high|throughput sequencing was performed for sequencing and bioinformatics analysis. The results showed that (1) the microbial community diversity of the soil samples was high and evenly distributed, and salt stress increased the richness and diversity of the microbial community in the rhizosphere, which was associated with the growth period. (2) Taxonomic analysis exhibited that the dominant classes and families were identical in all the soil groups: the dominant classes were Actinobacteria, Alphaproteobacteria, Gammaproteobacteria, Verrucomicrobiae, Saccharimonadia, Gemmatimonadetes, Bacteroidia and Acidobacteriia, and the dominant families were norank_o__Saccharimonadales, Sphingomonadaceae, Gemmatimonadaceae, Burkholderiaceae, norank_o__Gaiellales. (3) The abundance of Gammaproteobacteria and Verrucomicrobiae were significantly increased after salt stress treatment and basal calcium fertilizer application, and the richness improved more obviously with the prolongation of the growth period and the increase of salt concentration. The abundance of the two fungi was 1.2, 1.8 times and 1.6, 1.5 times higher than that of the control under high salt stress, respectively. However, basal calcium fertilizer application under salt stress reduced the abundance of Actinobacteria and Saccharimonadia, which decreased significantly with increasing salt concentration. Moreover, the decrease rate of the two fungi were larger at the flowering and needling stage. Chitinophagaceae and Opitutaceae were evidently affected by salt concentration and growth stages and increased dramatically with the increase of salt concentration. (4) The sequences related to amino acid metabolism, energy metabolism, cofactor and vitamin metabolism, and nucleotide metabolism were significantly enriched after basal calcium fertilizer treatment at the fast|growing stage. (5) Salt stress seriously inhibited the development of peanut kernel and reduced the yield. High salt stress reduced pod yield by 40.4%~50.0%.