Control of Pepper Blight by Bacillus velezensis MH24 and Induction of Pepper Transcriptomic Responses

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

Abstract

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

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.

Figures/Tables 9

References 38

[1]	Quesada-Ocampo LM, Parada-Rojas CH, Hansen Z, et al. Phytophthora capsici: recent progress on fundamental biology and disease management 100 years after its description [J]. Annu Rev Phytopathol, 2023, 61: 185-208.
[2]	Tian S, Peng Q, Du XR, et al. Phytophthora effector exploits WY module truncation to manipulate Nt-acetylation-mediated AtMBP-1 turnover and suppress plant immunity [J]. Sci Adv, 2025, 11(50): eady1482.
[3]	Bowers JH. Effect of soil temperature and soil-water matric potential on the survival of Phytophthora capsici in natural soil [J]. Plant Dis, 1990, 74(10): 771.
[4]	王锐, 张正海, 曹亚从, 等. 辣椒疫病的发生规律及综合防治技术 [J]. 辣椒杂志, 2025, 23(4): 12-21.
	Wang R, Zhang ZH, Cao YC, et al. The occurrence pattern and comprehensive control technology of Phytophthora blight in pepper [J]. J China Capsicum, 2025, 23(4): 12-21.
[5]	黄大野, 余志斌, 杜公福, 等. 淡紫褐链霉菌NBF715防控辣椒疫病研究 [J]. 北方园艺, 2022(17): 51-56.
	Huang DY, Yu ZB, Du GF, et al. Control effect of Streptomyces enissocaesilis NBF715 on Phytophthora blight of pepper [J]. North Hortic, 2022(17): 51-56.
[6]	Peng YX, Zhou C, Qiu FY, et al. Acid-resistant Bacillus velezensis effectively controls pathogenic Colletotrichum capsiciand improves plant health through metabolic interactions [J]. Appl Environ Microbiol, 2025, 91(7): e00340-e00325.
[7]	穆晓清, 鲁耀雄, 戴良英, 等. 贝莱斯芽孢杆菌YFB3-1对辣椒疫霉的抑菌效果及其抑菌物质 [J]. 农业生物技术学报, 2024, 32(4): 859-872.
	Mu XQ, Lu YX, Dai LY, et al. Antibacterial effect of Bacillus velezensis YFB3-1 on Phytophthora capsici and its antibacterial substances [J]. J Agric Biotechnol, 2024, 32(4): 859-872.
[8]	Ma S, Wang YJ, Teng W. Bacillus velezensis K-9 as a potential biocontrol agent for managing potato scab [J]. Plant Dis, 2023, 107(12): 3943-3951.
[9]	Wang ZQ, Zhao YK, Shao JH, et al. Rhizosphere domestication enhances root colonization and plant growth promotion performance of Bacillus velezensis SQR9 [J]. Front Microbiol, 2025, 16: 1638130.
[10]	司方洁, 任金瑶, 黄涛祥, 等. 贝莱斯芽孢杆菌5YN8生物被膜在防治番茄灰霉病过程中的功能研究 [J]. 中国生物防治学报, 2022, 38(5): 1223-1230.
	Si FJ, Ren JY, Huang TX, et al. The function of Bacillus velezensis 5YN8 biofilm in controlling of Botrytis cinerea in tomato [J]. Chin J Biol Control, 2022, 38(5): 1223-1230.
[11]	祝文慧, 秦溥, 赵岩, 等. 两种芽孢杆菌对苗期土传辣椒疫病的防控作用 [J]. 中国生物防治学报, 2023, 39(5): 1235-1243.
	Zhu WH, Qin P, Zhao Y, et al. Prevention and control effect of two Bacillus strains on soil-borne Phytophthora capsici in seedling stage [J]. Chin J Biol Control, 2023, 39(5): 1235-1243.
[12]	周池, 周诗晶, 陶禹, 等. 贝莱斯芽孢杆菌XY40-1: 全基因组特征分析及对辣椒疫病的生物防治效果评价 [J]. 微生物学报, 2024, 64(12): 4882-4901.
	Zhou C, Zhou SJ, Tao Y, et al. Bacillus velezensis XY40-1: whole genomic characteristics and biocontrol effects on pepper Phytophthora blight [J]. Acta Microbiol Sin, 2024, 64(12): 4882-4901.
[13]	王芳, 宁丽平, 邓稳桥, 等. 贝莱斯芽孢杆菌C1B1生防活性及促生作用研究 [J]. 中国生物防治学报, 2024, 40(4): 948-957.
	Wang F, Ning LP, Deng WQ, et al. Biocontrol activity and growth promoting effect of Bacillus velezensis C1B1 [J]. Chin J Biol Control, 2024, 40(4): 948-957.
[14]	王麒, 许婧霞, 张亚妮, 等. 贝莱斯芽孢杆菌 (Bacillus velezensis) JJYY防控土传病害效果评价及其全基因组测序分析和抗菌成分鉴定 [J]. 微生物学通报, 2024, 51(1): 155-171.
	Wang Q, Xu JX, Zhang YN, et al. Bacillus velezensis JJYY against soil-borne diseases: biocontrol effect, whole genome sequencing, and antimicrobial components [J]. Microbiol China, 2024, 51(1): 155-171.
[15]	田淼, 彭玉飞, 吕红, 等. 非洲哈茨木霉LMNS-M9的鉴定、生物学特性及其对藜麦的促生作用 [J]. 微生物学通报, 2023, 50(9): 3848-3865.
	Tian M, Peng YF, Lü H, et al. Trichoderma afroharzianum LMNS-M9: identification, biological characteristics, and growth-promoting effect on quinoa [J]. Microbiol China, 2023, 50(9): 3848-3865.
[16]	Liu Y, Yao SX, Deng LL, et al. Different mechanisms of action of isolated epiphytic yeasts against Penicillium digitatum and Penicillium italicum on Citrus fruit [J]. Postharvest Biol Technol, 2019, 152: 100-110.
[17]	Sang MK, Chun SC, Kim KD. Biological control of Phytophthora blight of pepper by antagonistic rhizobacteria selected from a sequential screening procedure [J]. Biol Control, 2008, 46(3): 424-433.
[18]	Chemeltorit PP, Mutaqin KH, Widodo W. Combining Trichoderma hamatum THSW13 and Pseudomonas aeruginosa BJ10-86: a synergistic chili pepper seed treatment for Phytophthora capsici infested soil [J]. Eur J Plant Pathol, 2017, 147(1): 157-166.
[19]	Yang MM, Xu LP, Xue QY, et al. Screening potential bacterial biocontrol agents towards Phytophthora capsici in pepper [J]. Eur J Plant Pathol, 2012, 134(4): 811-820.
[20]	赵欣, 郝林. 解淀粉芽孢杆菌HRH317对串珠镰孢菌菌丝形态和超微结构的影响 [J]. 植物保护学报, 2020, 47(1): 110-118.
	Zhao X, Hao L. Effects of Bacillus amyloliquefaciens HRH317 on mycelial morphology and ultrastructure of Fusarium moniliforme [J]. J Plant Prot, 2020, 47(1): 110-118.
[21]	Lu ZY, Chen ML, Long XY, et al. Biological potential of Bacillus subtilis BS45 to inhibit the growth of Fusarium graminearum through oxidative damage and perturbing related protein synthesis [J]. Front Microbiol, 2023, 14: 1064838.
[22]	Haq IU, Kennedy P, Schreiner KM, et al. Gene expression by a model fungus in the ascomycota provides insight into the decay of fungal necromass [J]. Environ Microbiol, 2024, 26(12): e70006.
[23]	Podder S, Saha D, Ghosh TC. Deciphering the intrinsic properties of fungal proteases in optimizing phytopathogenic interaction [J]. Gene, 2019, 711: 143934.
[24]	Xiong XP, Sun SC, Zhang XY, et al. GhWRKY70D13 regulates resistance to Verticillium dahliae in cotton through the ethylene and jasmonic acid signaling pathways [J]. Front Plant Sci, 2020(11): 69.
[25]	韩威山, 张江一, 方菲菲, 等. 辣椒疫霉致病、抗病和生物防治的分子机制研究进展 [J]. 北方园艺, 2025(10): 118-125.
	Han WS, Zhang JY, Fang FF, et al. Research progress on the molecular mechanism of pathogenesis, disease resistant and biological control of Phytophthora capsici [J]. North Hortic, 2025(10): 118-125.
[26]	Man J, Gallagher JP, Bartlett M. Structural evolution drives diversification of the large LRR-RLK gene family [J]. New Phytol, 2020, 226(5): 1492-1505.
[27]	Van der Does D, Boutrot F, Engelsdorf T, et al. The Arabidopsis Leucine-rich repeat receptor kinase MIK2/LRR-KISS connects cell wall integrity sensing, root growth and response to abiotic and biotic stresses [J]. PLoS Genet, 2017, 13(6): e1006832.
[28]	Li P, Xie LZ, Li W, et al. An oomycete effector targets host calmodulin to suppress plant immunity [J]. Plant J, 2025, 123(5): e70457.
[29]	Bhagat N, Mansotra R, Patel K, et al. Molecular warfare between pathogenic Fusarium oxysporum R1 and host Crocus sativus L. unraveled by dual transcriptomics [J]. Plant Cell Rep, 2024, 43(2): 42.
[30]	Jia CP, Guo B, Wang BK, et al. Integrated metabolomic and transcriptomic analysis reveals the role of phenylpropanoid biosynthesis pathway in tomato roots during salt stress [J]. Front Plant Sci, 2022, 13: 1023696.
[31]	Lee SH, Park YJ, Park SU, et al. Expression of genes related to phenylpropanoid biosynthesis in different organs of Ixeris dentata var. albiflora [J]. Molecules, 2017, 22(6): 901.
[32]	Han Z, Schneiter R. Dual functionality of pathogenesis-related proteins: defensive role in plants versus immunosuppressive role in pathogens [J]. Front Plant Sci, 2024, 15: 1368467.
[33]	Kaur A, Kaur S, Kaur A, et al. Pathogenesis-related proteins and their transgenic expression for developing disease-resistant crops: strategies progress and challenges [M]//Case Studies of Breeding Strategies in Major Plant Species. London: IntechOpen, 2023.
[34]	Wang F, Shen SS, Zhao CP, et al. TaPR1 interacts with TaTLP1 via the αIV helix to be involved in wheat defense to Puccinia triticina through the CAPE1 motif [J]. Front Plant Sci, 2022, 13: 874654.
[35]	Wang Q, Li MG, Lu M, et al. Expression analysis of pathogenesis-related protein genes revealed the key RrPRs involved in SA- and MeJA-mediated top-rot disease resistance in Rosa roxburghii fruit [J]. Physiol Mol Plant Pathol, 2024, 133: 102345.
[36]	Guidetti-Gonzalez S, Carrer H. Putative resistance genes in the CitEST database [J]. Genet Mol Biol, 2007, 30(3 ): 931-942.
[37]	Tailor A, Bhatla SC. R gene-mediated resistance in the management of plant diseases [J]. J Plant Biochem Biotechnol, 2024, 33(1): 5-23.
[38]	Nabi Z, Manzoor S, Nabi SU, et al. Pattern-Triggered Immunity and Effector-Triggered Immunity: crosstalk and cooperation of PRR and NLR-mediated plant defense pathways during host-pathogen interactions [J]. Physiol Mol Biol Plants, 2024, 30(4): 587-604.

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	—

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	—

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

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