玉米茎腐病生防菌株的筛选鉴定及其田间防效

Screening and identification of a biocontrol strain against maize stalk rot and evaluation of its field control effect

摘要:

【背景】近年来，玉米茎腐病已成为我国玉米生产中的一大病害威胁，对我国玉米产业以及国家粮食安全构成了严峻挑战。【目的】筛选出能够有效防治玉米茎腐病的生防菌株，明确其最佳发酵条件及其对玉米茎腐病的防治效果，为玉米茎腐病绿色防控技术研发提供理论基础和实践支撑。【方法】采用稀释涂布法和平板对峙法，对禾谷镰孢(Fusarium graminearum)进行生防菌株的筛选；运用生理生化和分子生物学技术对所筛选的生防菌株进行鉴定；对生防菌株的发酵条件进行优化，并进一步将其加工成种衣剂；通过室内盆栽试验与室外田间试验检测生防菌株在促进玉米生长及防治茎腐病方面的效果。【结果】筛选出对禾谷镰孢具有显著拮抗活性的贝莱斯芽孢杆菌(Bacillus velezensis) SHB23，其抑菌率高达73.86%。该菌株对拟轮枝镰孢(Fusarium verticillioides)、大斑病凸脐蠕孢(Setosphaeria turcica)、尖孢镰孢(Fusarium oxysporum)、炭色长蠕孢(Cochliobolus carbonum)和新月弯孢霉(Curvularia lunata)等多种玉米病害病原菌展现出明显的抑制效果，抑菌率为63.17%−79.76%。菌株SHB23的最适碳源为5%乳糖，最适氮源为0.5%黄豆饼粉，最适宜的无机盐为0.1%硫酸镁。最佳发酵条件为接种量6.0%、装液量75 mL/250 mL、pH 7.0、温度37℃、转速200 r/min以及发酵时间24 h。室内盆栽试验和室外田间试验均证实，菌株SHB23制成的种衣剂能显著促进玉米生长，并有效提高玉米茎腐病的防治效果。【结论】筛选出高效拮抗禾谷镰孢的贝莱斯芽孢杆菌SHB23，其制成的种衣剂在促进玉米生长和防治茎腐病方面的效果显著，在玉米茎腐病生防菌剂研发及绿色防控技术中具有潜在的应用前景。

Abstract:

[Background] In recent years, maize stalk rot has become a major disease threatening maize production in China, posing a serious challenge to the maize industry and national food security. [Objective] To screen out a biocontrol strain that can effectively control maize stalk rot, clarify its optimal fermentation conditions, and evaluate its control effect on maize stalk rot, thus providing a theoretical basis and practical support for the development of green prevention and control technology for this disease. [Methods] The biocontrol strain against Fusarium graminearum was screened by the dilution coating method and the plate confrontation method. The selected biocontrol strain was identified based on physiological, biochemical, and molecular biological evidence. The fermentation conditions of the strain were optimized and the strain was prepared into a seed coating agent. An indoor pot experiment and a field experiment were carried out to evaluate the effects of the biocontrol strain on maize growth and stem rot. [Results] Bacillus velezensis strain SHB23 with significant antagonistic activity against F. graminearum was successfully screened out, and its inhibition rate was as high as 73.86%. The strain showed obvious inhibitory effects on various maize pathogens such as Fusarium verticillioides, Setosphaeria turcica, Fusarium oxysporum, Cochliobolus carbonum, and Curvularia lunata, with the inhibition rate ranging from 63.17% to 79.76%. The optimum carbon source, nitrogen source, and inorganic salt for the culture of SHB23 were 5% lactose, 0.5% soybean cake powder, and 0.1% magnesium sulfate, respectively. The fermentation conditions of the strain were optimized as fermentation with an inoculum amount of 6.0% and a liquid volume of 75 mL/250 mL at pH 7.0, 37 ℃, and 200 r/min for 24 h. Both pot and field experiments confirmed that the seed coating agent prepared with SHB23 significantly promoted maize growth and controlled maize stem rot. [Conclusion] B. velezensis SHB23 with high antagonistic activity against F. graminearum was successfully screened out. The seed coating agent prepared with B. velezensis SHB23 had significant effects of promoting maize growth and preventing stem rot, demonstrating promising application prospects in the development of biocontrol agents and green prevention and control technology against maize stem rot.