番茄根际酚酸累积对青枯菌入侵的影响

Effects of phenolic acid accumulation in tomato rhizosphere on Ralstonia solanacearum invasion

【目的】探明番茄根际酚酸累积对青枯菌入侵的影响,为阐明番茄青枯病的发病机理提供理论依据。【方法】通过96孔板培养青枯菌研究5种不同酚酸类物质(苯丙酸、苯甲酸、咖啡酸、阿魏酸和丁香酸)单品对青枯菌生长的影响;应用高通量测序方法检测酚酸累积后土壤细菌群落多样性的变化,应用选择性培养基检测土壤中青枯菌的数量变化;通过主成分分析(PCA)、冗余分析(RDA)和相关分析等方法,分析不同酚酸处理后土壤细菌群落变化对青枯菌生长繁殖的影响。【结果】苯丙酸、苯甲酸、咖啡酸、阿魏酸和丁香酸均有利于青枯菌生长,其中咖啡酸的作用最明显,青枯菌生长的OD_(600 nm)达0.17,显著高于其他酚酸处理(P<0.05,下同)。与空白对照相比,各酚酸类物质持续累积均会显著降低土壤细菌群落Sobs、Shannon、ACE和Chao1多样性指数;苯甲酸、咖啡酸、阿魏酸和丁香酸处理后土壤细菌门分类水平上的优势种群由变形菌门(Proteobacteria)转变为厚壁菌门(Firmicutes),其中丁香酸处理后土壤厚壁菌门的相对丰度最高,达90.4%,而苯丙酸处理与其他酚酸处理变化趋势存在明显差异,其优势种群为变形菌门,相对丰度达47.3%。RDA结果显示,厚壁菌门相对丰度与土壤有机质含量呈正相关,变形菌门相对丰度与p H、NO_(3)-N和NH_(4)-N呈正相关。在酚酸物质处理的土壤中接种青枯菌28 d后,青枯菌的繁殖数量显著高于空白对照,其中以丁香酸处理最高,达8.16 lg CFU/g土。相关分析结果显示,土壤中青枯菌数量与厚壁菌门相对丰度呈显著正相关,而与其他群落相对丰度呈显著负相关。【结论】番茄根际土壤累积的酚酸类物质可破坏土壤细菌群落结构,使其抵御青枯菌入侵的能力减弱,从而加快病害发生。

【Objective】This study aimed to investigate the effects of phenolic acid accumulation in the tomato rhizo‐sphere on the invasion of Ralstonia solanacearum,providing theoretical support for elucidating the pathogenesis of to‐mato bacterial wilt.【Method】The effects of 5 phenolic acid substances(phenylpropanoic acid,benzoic acid,caffeic acid,ferulic acid and syringic acid)on the growth of R.solanacearum were examined using 96-well plate culture.The changes in soil bacterial community diversity after phenolic acid accumulation were detected using high-throughput se‐quencing methods.The population changes of R.solanacearum in soil were detected using selective culture media.Princi‐pal component analysis(PCA),redundancy analysis(RDA)and correlation analysis were employed to analyze the ef‐fects of soil bacterial community changes on the growth and reproduction of R.solanacearum under different phenolic acid treatments.【Result】Phenylpropanoic acid,benzoic acid,caffeic acid,ferulic acid and syringic acid promoted R.so‐lanacearum growth,with caffeic acid showing the most obvious effect.The OD_(600nm) of R.solanacearum reached 0.17 in the caffeic acid treatment,which was significantly higher than those in other treatments(P<0.05,the same below).Com‐pared with blank control,the continuous accumulation of each phenolic acid substance significantly reduced the diversity indexes of soil bacterial communities(Sobs,Shannon,ACE and Chao1 indexes).After benzoic acid,caffeic acid,feru‐lic acid and syringic acid treatments,the dominant phyla shifted from Proteobacteria to Firmicutes.The relative abun‐dance of Firmicutes in soil was the highest in the syringic acid treatment,reaching 90.4%.However,the phenylpropanoic acid treatment showed a significant different trend compared with other phenolic acid treatments,with Proteobacteria be‐coming the dominant phylum(47.3%relative abundance).RDA revealed a positive correlation between relative abun‐dance of Firmicutes and soil organic matter content,and a positive correlation between relative abundance of Proteobacte‐ria and pH,NO_(3)-N,NH_(4)-N.After 28 d of R.solanacearum inoculation in soils treated with phenolic acids,the reproduc‐tive quantity of R.solanacearum was significantly higher than that of blank control,with the highest population(8.16 lg CFU/g soil)observed in the syringic acid treatment.Correlation analysis showed that the population of R.solanacearum was significantly positively correlated with the relative abundance of Firmicutes,but it was significantly negatively corre‐lated with the relative abundance of other communities.【Conclusion】The accumulation of phenolic acid substances in to‐mato rhizosphere disrupts the soil bacterial community structure,weakening its resistance to R.solanacearum invasion and accelerating disease development.