贝莱斯芽胞杆菌MH24防控辣椒疫病及诱导辣椒转录组学的研究

doi:10.13560/j.cnki.biotech.bull.1985.2026-0097

摘要/Abstract

摘要：

目的探究贝莱斯芽胞杆菌（Bacillus velezensis）MH24对辣椒疫病的防控效果及分子机制，为该菌株在生物防治领域的应用提供理论依据。方法通过离体与活体试验相结合探究菌株MH24抑菌活性及辣椒抗性机制。采用平板对峙、电镜观察及水解酶活性测定解析体外抑菌作用；通过盆栽试验验证活体防病效果；利用转录组测序筛选抗病差异基因，并结合RT-qPCR验证关键基因表达，揭示其抑菌及诱导植株抗病的分子机理。结果离体抑菌试验表明，MH24对辣椒疫霉（Phytophthora capsici）菌丝生长抑制率达75.64%，扫描电镜观察可见菌丝表面出现皱缩、断裂及塌陷等典型超微结构损伤，同时该菌株能高效分泌淀粉酶、蛋白酶等多种胞外水解酶。盆栽防效试验结果表明，MH24发酵液灌根处理能显著降低辣椒疫病病情指数，防效达88.23%。与对照组相比，MH24处理后辣椒叶片共鉴定出146个显著差异表达基因，其中114个上调表达，32个下调表达；这些差异基因主要富集于信号识别、信号传导、次生代谢及直接抗病四大功能模块，涉及LRR-RLK类受体激酶、MAPK级联信号通路组分以及PR-5家族病程相关蛋白等关键抗性基因。进一步抗性诱导试验证实，经MH24发酵液预处理的辣椒叶片在接种病原菌后病斑直径显著缩小，诱导防效达41.20%，进一步验证了该菌株激活植株防御反应的能力。结论贝莱斯芽胞杆菌MH24通过分泌抗菌活性物质及水解酶直接抑制病原菌生长，同时激活植株系统获得性抗性途径，实现对辣椒疫病的协同防控。

关键词: 贝莱斯芽胞杆菌, 转录组分析, 诱导抗性, 辣椒疫霉, 生防能力, 实时荧光定量PCR, 水解酶

Abstract:

Objective This study aimed to evaluate the efficacy of Bacillus velezensis MH24 against pepper blight and to elucidate its molecular mechanism, thereby providing a theoretical basis for the application of this strain in biological control. Method The antifungal activity and resistance mechanism of MH24 were investigated using both in vitro and in vivo approaches. In vitro antibacterial effects were assessed by plate confrontation assays, scanning electron microscopy (SEM), and hydrolytic enzyme activity assays. In vivo disease control efficacy was verified by pot experiments. Transcriptome sequencing was performed to identify differentially expressed genes (DEGs) related to disease resistance, and quantitative real-time PCR (RT-qPCR) was used to validate the expression of key genes, thereby revealing the molecular mechanisms underlying antifungal activity and induced plant resistance. Result In vitro assays showed that MH24 inhibited mycelial growth of Phytophthora capsici by 75.64%. SEM revealed typical ultrastructural damage, including mycelial shrinkage, breakage, and collapse. MH24 also efficiently secreted various extracellular hydrolytic enzymes, such as amylase and protease. Pot experiments demonstrated that root irrigation with MH24 fermentation broth significantly reduced the disease index of pepper blight, achieving a control efficacy of 88.23%. Compared with the control group, a total of 146 significantly DEGs were identified in pepper leaves after MH24 treatment, of which 114 were up-regulated and 32 down-regulated. These DEGs were mainly enriched in four functional modules: signal recognition, signal transduction, secondary metabolism, and direct disease resistance. Key resistance genes identified included LRR-RLK receptor-like kinases, MAPK cascade signaling pathway components, and PR-5 family pathogenesis-related proteins. Further resistance induction assays confirmed that pepper leaves pretreated with MH24 fermentation broth exhibited significantly reduced lesion diameters after pathogen inoculation, with an induced resistance efficacy of 41.20%, further validating the ability of this strain to activate plant defense responses. Conclusion Bacillus velezensis MH24 directly inhibits pathogen growth by secreting antimicrobial active substances and hydrolytic enzymes while simultaneously activating the plant systemic acquired resistance (SAR) pathway, thereby achieving synergistic control of pepper blight.

Key words: Bacillus velezensis, transcriptome analysis, induced resistance, Phytophthora capsici, biocontrol ability, real-time fluorescent quantitative PCR (RT-qPCR), hydrolase

李瑾琪, 姚经武, 袁勤峰, 刘瑜, 曹春霞, 尹飞虎, 黄大野. 贝莱斯芽胞杆菌MH24防控辣椒疫病及诱导辣椒转录组学的研究[J]. 生物技术通报, 2026, 42(11): 230-239.

LI Jin-qi, YAO Jing-wu, YUAN Qin-feng, LIU Yu, CAO Chun-xia, YIN Fei-hu, HUANG Da-ye. Control of Pepper Blight by Bacillus velezensis MH24 and Induction of Pepper Transcriptomic Responses[J]. Biotechnology Bulletin, 2026, 42(11): 230-239.

图/表 9

表1 MH24防控辣椒疫霉的盆栽效果

Table 1 Efficacy of strain MH24 against Phytophthora capsici in pot experiments

处理 Treatments	病情指数 Disease index	防效 Control effect （%）
MH24菌剂20倍 MH24 bioagent diluted 20 times	8.33±0.32c	88.23a
MH24菌剂40倍 MH24 bioagent diluted 40 times	17.50±0.20b	75.30c
烯酰吗啉 Dimethomorph （500 μg/mL）	8.33±0.17c	88.23a
对照 CK	70.83±0.51a	—

图1 辣椒疫霉单菌落CK组（A）与MH24处理组（B）

Fig. 1 Single colony of Phytophthora capsici in the CK group (A) and the MH24-treated group (B)

图2 MH24对辣椒疫霉菌丝作用的扫描电镜观察A：CK组；B：处理组

Fig. 2 SEM observation of the effect of MH24 on mycelia of Phytophthora capsiciA: CK group. B: Treatment group

图3 MH24水解酶活性测定A：淀粉培养基；B：β-1，3-葡聚糖培养基；C：蛋白质培养基；D：羧甲基纤维素培养基

Fig. 3 Assay of hydrolase activity of MH24A: Starch medium. B: β-1,3-glucan medium. C: Protein medium. D: Carboxymethyl cellulose medium

表2 RNA-seq数据质量分析

Table 2 Statistics of RNA-seq data quality

样品 Sample	原始读长 Raw reads number （bp）	过滤读长 Clean reads number （bp）	有效碱基数 Clean bases （G）	Q20 （%）	Q30 （%）	GC含量 GC content （%）	总读段对数 Total read pairs
CK-1	41 389 232	41 212 371	12.19	99.34	96.45	42.81	41 212 371
CK-2	42 273 359	42 085 611	12.47	99.33	96.45	42.62	42 085 611
CK-3	36 156 617	35 989 458	10.65	99.37	96.71	42.60	35 989 458
MH24-1	39 076 275	38 873 625	11.52	99.34	96.46	42.59	38 873 625
MH24-2	31 481 578	31 312 465	9.26	99.21	96.93	42.52	31 312 465
MH24-3	41 502 293	41 310 245	12.22	99.32	96.29	42.58	41 310 245

图4 差异表达基因火山图

Fig. 4 Volcano plot of differentially expressed genes

图5 差异表达基因的GO（A）和KEGG（B）富集分析

Fig. 5 GO (A) and KEGG (B) enrichment analysis of differentially expressed genes

图6 RNA-seq和RT-qPCR基因表达结果比较

Fig. 6 Comparison of gene expression results between RNA-seq and RT-qPCR

表3 MH24诱导辣椒抗性的盆栽验证

Table 3 Potted plant validation of MH24-induced resistance in chili plants

处理

Treatments

病原菌直径

Diameter of pathogenic bacteria （cm）

防效

Control effect （%）

MH24 菌剂20倍

MH24 bioagent diluted 20 times

1.57±0.49c

41.20

MH24 菌剂40倍

MH24 bioagent diluted 40 times

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