摘要
茶树是我国重要的经济作物,然而长期宿根连作铁观音茶园存在土壤微生物群落结构失衡、病害加重等连作障碍问题,探究铁观音茶树连作障碍形成的分子机制对寻求有效的防控技术具有重要意义。采用微生物分离纯化、平板对峙等方法对铁观音茶树根际病原菌及其拮抗菌进行分离、鉴定,并对不同宿根连作年限(0、1、10、20 a)铁观音茶树根际土壤中的病原菌和拮抗菌数量进行定量分析;同时运用高效液相色谱(HPLC)技术分析不同连作年限根际土壤中酚酸含量变化,并模拟土壤中各酚酸配比,研究酚酸类物质对茶树根际病原菌及其拮抗菌的影响。结果显示,从连作20 a患病铁观音茶树根系分离鉴定到1株病原真菌链格孢菌(Alternaria sp.),并从根际土壤中筛选到1株拮抗菌假单胞菌(Pseudomonas sp.)。荧光定量PCR分析发现,与1 a茶园相比,20 a茶园土壤中的链格孢菌绝对含量显著偏高,而假单胞菌含量却显著偏低。连作茶园根际土壤中共检测到对羟基苯甲酸、香草酸、丁香酸、香兰素、阿魏酸5种酚酸类物质,其平均配比为38∶229∶11∶11∶3。连作条件下酚酸类物质并未在土壤中累积,而是随种植年限的延长呈现出先增加后降低的趋势。模拟试验发现,中低浓度(30~120μmol·L^(-1))的混合酚酸能够显著促进链格孢菌菌丝的生长,单一酚酸对羟基苯甲酸、香草酸和丁香酸在低浓度(30μmol·L^(-1)和60μmol·L^(-1))时也能够显著促进链格孢菌菌丝的生长。对羟基苯甲酸对假单胞菌的生长有抑制作用,并且随着浓度的增加抑制作用增强,混合酚酸以及其他单一酚酸对假单胞菌的生长无明显作用。由此可见,铁观音根系分泌物酚酸类物质对根际土壤关键微生物菌群具有不同的生态效应,是引起微生物群落结构失衡、病害增加等连作障碍问题的重要因素。研究结果为进一步揭示铁观音茶树连作障碍机理提供一些理论依据。
Tea plant is an important economic crop in in China.Long-term continuous cropping of tea plants resulted in severe problems such as the imbalance of soil microbial community structure,soil disease exacerbation.Exploring the molecular mechanism underlying the formation of continuous cropping obstacles in Tieguanyin tea gardens is of great significance for seeking effective techniques for preventing and controlling the continuous cropping obstacle phenomenon.In this study,the pathogen and its antagonistic bacteria were isolated from the rhizosphere of Tieguanyin tea garden and identified by methods such as microbial isolation and purification,and plate confrontation.Quantitative analysis was conducted on the number of pathogen and its antagonistic bacteria in the rhizospheric soils of different continuous cropping years(0,1,10,and 20 years).Simultaneously,high-performance liquid chromatography(HPLC)technology was used to detect the changes of phenolic acid contents in the rhizospheric soils of different continuous cropping years,and the ratio of various phenolic acids in the soils was simulated to investigate the effects of phenolic acids on the rhizospheric pathogen and its antagonistic bacteria.The results show that one pathogenic fungus Alternaria sp.was isolated and identified from the infected roots of Tieguanyin under 20 years’continuous cropping,and an antagonistic bacteria Pseudomonas sp.was identified from the rhizospheric soils.Fluorescence quantitative PCR analysis shows that the content of Alternaria sp.in 20 years’continuous cropping soils was significantly higher than 1 year tea garden,while the content of Pseudomonas sp.was significantly lower.Five phenolic acids,including p-hydroxybenzoic acid,vanillic acid,syringic acid,vanillin,and ferulic acid,were detected in the rhizospheric soils,with an average ratio of 38∶229∶11∶11∶3.Phenolic acids did not accumulate in the soils,but showed a trend of first increasing and then decreasing with the increase of continuous cropping years.Simulation experiments found that mixed phenolic acids at low to medium concentrations(30-120μmol·L^(-1))could significantly promote the mycelial growth of Alternaria sp.while single phenolic acid such as p-hydroxybenzoic acid,vanillic acid,and syringic acid at low concentrations(30μmol·L^(-1) and 60μmol·L^(-1))also significantly accelerated the mycelial growth of Alternaria sp..However,p-hydroxybenzoic acid had an inhibitory effect on the growth of Pseudomonas sp.,and the inhibitory effect increased with the increase of p-hydroxybenzoic acid concentration.Mixed phenolic acid and other single phenolic acids had no significant effect on the growth of Pseudomonas sp..Therefore,phenolic acids,the root exudates of Tieguanyin tea plants,have different ecological effects on the key microbial communities in the rhizospheric soils,and are important factors causing the imbalance of microbial community structure and the increase of severe diseases and other continuous cropping obstacles.The research results provided a theoretical basis for further revealing the mechanism of continuous cropping obstacles in Tieguanyin tea plants.
作者
李艳春
王义祥
叶菁
李兆伟
LI Yanchun;WANG Yixiang;YE Jing;LI Zhaowei(Institute of Resources,Environment and Soil Fertilizer,Fujian Academy of Agricultural Sciences/Fujian Key Laboratory of Agricultural Ecological Process of Red Soil Mountain,Fuzhou 350013,China;Life Sciences College of Fujian Agriculture and Forestry University,Fuzhou 350002,China)
出处
《茶叶科学》
CAS
CSCD
北大核心
2023年第6期823-834,共12页
Journal of Tea Science
基金
福建省自然科学基金(2019J01100)
中央引导地方科技发展专项(2021L3021)。
关键词
茶树
连作障碍
酚酸类物质
链格孢菌
假单胞菌
tea plant
continuous cropping obstacles
phenolic compounds
Alternaria sp.
Pseudomonas sp.
