外源棕榈酸对西瓜连作土壤微生物及枯萎病菌致病力的影响

发布时间：2018-10-26 07:20

【摘要】：西瓜枯萎病是由西瓜专化型尖孢镰刀菌引起的土传性病害。前人研究发现,小麦伴生西瓜能够调控土壤微生物菌群,从而减轻西瓜枯萎病。棕榈酸作为小麦根系分泌物的主要成分,其在土壤中的含量与枯萎病严重程度呈负相关。但是在土壤条件下,外源棕榈酸对土壤微生物菌群产生哪些影响,鲜有报道。另外,西瓜专化型尖孢镰刀菌侵染寄主植物过程中,其释放的镰刀菌酸和植物细胞壁降解酶能够反映其对寄主的致病能力,因而有必要探明棕榈酸对西瓜专化型尖孢镰刀菌致病力的影响。本研究设置了4个棕榈酸浓度,即0 mmol/kg、0.5 mmol/kg、1.0 mmol/kg、1.5mmol/kg干土,通过盆栽试验和Mi Seq测序技术研究了不同浓度的外源棕榈酸对西瓜连作土壤微生物多样性、群落结构和菌群分布的影响。此外还通过体外培养基试验研究了不同浓度的外源棕榈酸对西瓜枯萎病菌致病力相关指标的影响。旨在揭示棕榈酸介导的土壤微生物菌群的动态变化在西瓜枯萎病防控方面发挥的重要作用。试验的主要结果如下:(1)西瓜盆栽试验结果表明,1.0 mmol/kg、1.5 mmol/kg棕榈酸显著降低了西瓜枯萎病发病率,对西瓜枯萎病有较好的防治效果。(2)土壤微生物丰富度和多样性分析结果表明,对于西瓜连作土壤真菌而言,0.5mmol/kg、1.0 mmol/kg、1.5 mmol/kg棕榈酸在定植前期降低了真菌丰富度和多样性,并且1.5 mmol/kg棕榈酸在定植后期降低了真菌多样性。对于西瓜连作土壤细菌而言,0.5 mmol/kg、1.0 mmol/kg、1.5 mmol/kg棕榈酸在定植前期对西瓜连作土壤细菌的丰富度和多样性无影响。(3)土壤微生物群落结构主坐标轴分析(PCo A)结果表明,对于西瓜连作土壤真菌而言,0.5 mmol/kg、1.0 mmol/kg、1.5 mmol/kg棕榈酸在定植前期和后期均改变了西瓜连作土壤真菌群落结构。对于西瓜连作土壤细菌而言,0.5 mmol/kg、1.0 mmol/kg、1.5 mmol/kg棕榈酸在定植前期均改变了西瓜连作土壤细菌群落结构。而且1.0 mmol/kg棕榈酸在定植后期也改变了西瓜连作土壤细菌群落结构。(4)土壤微生物菌群分布分析结果表明,对于西瓜连作土壤真菌而言,0.5 mmol/kg、1.0 mmol/kg、1.5 mmol/kg棕榈酸在定植前期和后期对接合菌门具有促进作用,而对子囊菌门具有抑制作用。1.0 mmol/kg棕榈酸在定植前期对担子菌门具有抑制作用,而在定植后期对担子菌门无影响。0.5 mmol/kg、1.0 mmol/kg、1.5 mmol/kg棕榈酸在定植前期和后期对被孢霉属具有促进作用,而对隐球菌属具有抑制作用。此外,0.5 mmol/kg、1.0 mmol/kg、1.5 mmol/kg棕榈酸在定植前期对镰刀菌属具有抑制作用。对于西瓜连作土壤细菌而言,1.0 mmol/kg、1.5 mmol/kg棕榈酸在定植前期对变形菌门具有促进作用,而对绿弯菌门具有抑制作用;同时0.5 mmol/kg棕榈酸对绿弯菌门也有抑制作用。此外,1.0 mmol/kg棕榈酸芽单胞菌门具有抑制作用。但是,各浓度棕榈酸在定植后期对门水平细菌无影响。(5)西瓜枯萎病与土壤微生物菌群相关性分析结果表明,枯萎病的发病程度与接合菌门及被孢霉属的相对丰度呈负相关关系。(6)体外培养基试验结果表明,外源棕榈酸并非通过影响西瓜专化型尖孢镰刀菌致病力的途径防控枯萎病。
[Abstract]:Watermelon fusarium wilt is a soil-borne disease caused by Fusarium oxysporum. Previous studies have found that wheat-associated watermelons can regulate soil microbial flora, thus reducing watermelon fusarium wilt. As the main component of wheat root exudates, palmitic acid had a negative correlation with the severity of fusarium wilt in soil. However, the effects of exogenous palmitic acid on soil microbial flora were seldom reported under soil conditions. In addition, the fusarium acid and the plant cell wall degrading enzyme released by the Fusarium oxysporum canarium can reflect its pathogenicity to the host, and therefore it is necessary to detect the effect of palmitic acid on the pathogenicity of fusarium oxysporum. Four palmitic acid concentrations, 0 mmol/ kg, 0.5 mmol/ kg, 1.0 mmol/ kg, 1. 5mmol/ kg dry soil were set up in this study. The effects of exogenous palmitic acid at different concentrations on microbial diversity, community structure and flora distribution in watermelon were studied by pot experiment and Mi Seq sequencing. In addition, the effects of exogenous palmitic acid at different concentrations on the pathogenicity of Fusarium oxysporum f.sp. were also studied in vitro. The purpose of this study is to reveal the important role of palmitic acid-mediated transformation of soil microbial flora in the prevention and control of watermelon wilt. The main results of experiment were as follows: (1) The pot experiment of watermelon showed that 1. 0mmol/ kg, 1.5 mmol/ kg palmitic acid significantly reduced the incidence of watermelon fusarium wilt, and had better control effect on watermelon wilt. (2) The results of soil microbial richness and diversity showed that 0. 5mmol/ kg, 1. 0mmol/ kg, 1.5 mmol/ kg palmitic acid decreased the fungus richness and diversity in the early stage of field planting, and 1. 5 mmol/ kg palmitic acid reduced the diversity of fungi at the later stage of field planting. For watermelon soil bacteria, 0. 5 mmol/ kg, 1.0 mmol/ kg, 1.5 mmol/ kg palmitic acid had no effect on the richness and diversity of soil bacteria in watermelon in early stage. (3) The results of principal axis analysis (PCo A) of soil microbial community structure showed that 0. 5 mmol/ kg, 1. 0mmol/ kg, 1.5 mmol/ kg palmitic acid changed the structure of soil fungal community in watermelon. The bacterial community structure of watermelon was changed by 0.5 mmol/ kg, 1.0 mmol/ kg and 1.5 mmol/ kg palmitic acid. In addition, 1. 0 mmol/ kg palmitic acid also changed the bacterial community structure of watermelon in late stage. (4) The results of soil microbial flora distribution showed that 0. 5 mmol/ kg, 1. 0mmol/ kg, 1.5 mmol/ kg palmitic acid had a catalytic role in the early and late stage of colonization for watermelon and soil fungi. The inhibitory effect on the basidiomycotina was inhibited by 1. 0 mmol/ kg palmitic acid at the early stage of colonization, but no effect on basidiomycetous doors was observed at the later stage of colonization. but has inhibitory effect on cryptococcosis. In addition, 0. 5 mmol/ kg, 1.0 mmol/ kg, 1.5 mmol/ kg palmitic acid had inhibitory effect on fusarium at the early stage of colonization. 1. 0 mmol/ kg, 1. 5 mmol/ kg palmitic acid had a promoting effect on the deformation bacteria gate in the early stage of field planting, but also inhibited the green-bending bacteria door at the same time. At the same time, 0. 5 mmol/ kg palmitic acid had an inhibitory effect on the green-bending bacteria door. in addition, 1. 0 mmol/ kg palmitic acid sprout door had inhibitory effect. However, each concentration palmitic acid had no effect on the level of bacteria at the later stage of colonization. (5) The correlation between watermelon fusarium wilt and soil microbial flora showed that the degree of fusarium wilt was negatively correlated with the relative abundance of Zymophylum. (6) The results of in vitro culture medium test showed that exogenous palmitic acid was not able to prevent and control the fusarium wilt by affecting the pathogenic force of Fusarium oxysporum.
【学位授予单位】：东北农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S436.5;S154.3

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