人参栽培对致病镰刀菌的趋化性影响及其互作机制

Panax ginseng C. A. Meyer (Araliaceae), one of the most well-known Chinese herbal medicines, was cultivated in large scale of northeastern region of China. However, the yield is severely hindered by continuous cropping obstacles of P. ginseng. In brief, P. ginseng cannot be cultivated on the same land consecutively for an extended period, which is also a limiting bottleneck on the sustainable development of P. ginseng industry. The underlying mechanism regarding interaction of plant, soil and microorganism is still being explored in ginseng continuous cropping obstacles, and it is believed that it is related to the imbalance of rhizospheric micro-ecosystem under accumulation of ginseng root exudation. . Our research group found that there were more pathogenic microorganisms in the ginseng rhizospheric soil for the first time, such as Fusarium, Cryptococcus, and et al. However, there have been no reports on true reasons and the inducing factors of the increases of pathogenic Fusarium greatly so far. According to the preliminary study, we speculated that the chemotaxis of ginseng root secretions may be the key factor to induce the proliferation of Fusarium in soil. In order to confirm this hypothesis, the following three researches will be conducted in this project on the soil cultivated ginseng in Jilin province: (1) Next-generation pyrosequencing technology was used to analyze the dynamic succession law of pathogenic microbial community (Fusarium) in different cultivation years and growing seasons. (2) The capillary method and pot-soil regeneration experiment were used to research the chemotaxis of ginseng root exudate to Fusarium. (3) The interaction relationship among root secretions of ginseng, Fusarium and soil environment were explored by using Biolog, qRT-PCR and rDNA-DEEG technology combined with traditional culture.. The study will be helpful to illuminate the formation cause of increased of fungi and pathogenic microorganisms in the continuous cultivation soil of P. ginseng, and reveal the interaction relationship between the ginseng root secretion and soil microbial community in ginseng soil, while the results have important significance to explore the interaction mechanism forming ginseng continuous cropping obstacle, which also provide new ideas and technical support for controlling soil-borne disease management of Chinese herbal medicines.

人参（Panax ginseng）忌连作性极强，严重制约人参产业可持续发展。人参连作障碍的互作机制尚未阐明，多认为与人参根泌物介导下土壤微生态失衡有关。课题组首次发现栽参土壤中镰刀菌等病型微生物增多，但有关致病镰刀菌增殖的诱导因素迄今未见报道。根据前期研究，我们推测人参根系分泌物的趋化作用可能是诱导参地土壤中致病镰刀菌种群增殖的关键因素。为证实这一假说，我们以吉林省不同栽培年限人参根际土壤为研究对象，采用高通量测序技术分析不同栽培年限、栽培季节人参根际土壤中致病镰刀菌的动态演替规律；采用毛细管法及盆栽土壤回接试验，研究人参根系分泌物对致病镰刀菌的趋化作用；采用qRT-PCR、rDNA-DEEG和Biolog技术与传统培养相结合，探索人参根系分泌物—镰刀菌—土壤环境的互作关系，将有助于阐明人参连作土壤真菌化、病菌化成因，揭示人参连作障碍发生的互作机制，也为中药材连作障碍的合理防治提供新思路。

人参（Panax ginseng C. A. Mey.）是我国中医药和大健康产业独具特色的重要资源，忌连作性极强。连作障碍难题始终制约着人参产业的可持续发展。吉林省东部长白山区是我国人参主产区，现在国家已严令禁止伐林栽参，农田栽参成为一种新型栽参模式。“农田栽参”同样也面临着严重的连作障碍问题，农田土壤需改良后才能再栽参。人参连作障碍复合作用机制尚未阐明，多认为与其根际土壤的微生态失衡有关。课题组首次发现栽参土壤中镰刀菌等病型微生物增多，但有关致病镰刀菌增殖的诱导因素迄今未见报道。根据前期研究，我们推测人参根系分泌物的趋化作用可能是诱导参地土壤中致病镰刀菌种群增殖的关键因素。为证实这一假说，我们以吉林省不同栽培年限人参根际土壤为研究对象，采用高通量测序技术和qPCR相结合分析不同栽培年限、栽培季节人参根际土壤中致病镰刀菌的动态演替规律；采用毛细管法及盆栽土壤回接试验，研究人参根系分泌物对致病镰刀菌的趋化作用；采用高通量测序、Biolog技术与传统培养相结合，探索人参根系分泌物—镰刀菌—土壤环境的互作关系。本项目研究结果表明，人参栽培年限增加导致农田栽参土壤中腐质霉属、镰刀菌属等致病真菌丰度增加，青霉属、被孢霉属及木霉属等真菌丰度下降，土壤病菌化程度增加、真菌群落丰富度和多样性下降，农田参后地土壤改良应提早开展。高浓度人参根系分泌物对农田栽参土壤中致病镰刀菌有显著正趋化作用，但对木霉菌诱导趋化作用不明显，外源添加中高浓度人参根系提取物后农田栽参土壤中被孢霉属、镰刀菌属真菌群增殖，土壤真菌丰富度和多样性下降，从而导致农田栽参土壤微生态失衡。外源添加木霉菌和肥料合理配施有利于促进农田栽参土壤中微生物群落和代谢多样性增加，本研究为阐明农田栽参土壤中人参根系分泌物——土壤微生物（镰刀菌和木霉菌）——土壤环境提供理论依据和技术支撑，也为阐明人参连作土壤真菌化、病菌化成因，揭示人参连作障碍发生的互作机制，也为中药材连作障碍的合理防治提供新思路。