Biocontrol microbes are environment-friendly and safe for humans and animals. To seek biocontrol microbes effective in suppressing tomato gray mold is important for tomato production. Therefore, serial experiments were conducted to characterize the antagonism of Bacillus velezensis HY19, a novel self-isolated biocontrol bacterium, against Botrytis cinerea in vitro and the control on tomato gray mold in greenhouse. This bacterium produced extracellular phosphatase, protease, cellulose and siderophores, and considerably inhibited the growth of B. cinerea. A liquid chromatography-mass spectrometry (LC-MS) detected salicylic acid and numerous antifungal substances present in B. velezensis HY19 fermentation liquid (BVFL). When B. cinerea was grown on potato glucose agar, BVFL crude extract remarkably suppressed the fungal growth and reduced protein content and the activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). Transcriptome studies showed that BVFL crude extract significantly induced different expression of numerous genes in B. cinerea, most of which were down-regulated. Theses differently expressed genes were involved in the biological process, cell compartment, molecular functions, and metabolisms of glycine, serine, threonine, and sulfur in pathogen hyphae. Thus, this biocontrol bacterium antagonized B. cinerea in multiple ways due to the production of numerous antifungal substances that acted on multiple targets in the cells. BVFL significantly increased antioxidant enzyme activities in tomato leaves and decreased the incidence of tomato gray mold, with the control efficacies of 73.12–76.51%. Taken together, B. velezensis HY19 showed a promising use potential as a powerful bioagent against tomato gray mold.

生物防治微生物对人类和动物都是环境友好和安全的。寻找有效抑制番茄灰霉病的生防微生物对番茄生产具有重要意义。因此，开展了一系列实验，表征了一种新型自分离生防菌Bacillus velezensis HY19在体外对Botrytis cinerea的拮抗作用和对温室番茄灰霉病的防治作用。这种细菌产生细胞外磷酸酶、蛋白酶、纤维素和铁载体，并显着抑制灰霉病菌的生长。液相色谱-质谱 (LC-MS) 检测到B. velezensis HY19 发酵液 (BVFL) 中存在水杨酸和多种抗真菌物质。什么时候B. cinerea在马铃薯葡萄糖琼脂上生长，BVFL 粗提物显着抑制真菌生长并降低蛋白质含量和过氧化氢酶 (CAT)、超氧化物歧化酶 (SOD) 和过氧化物酶 (POD) 的活性。转录组研究表明，BVFL粗提物显着诱导灰霉病菌中众多基因的不同表达，其中大部分基因被下调。这些不同表达的基因参与了病原体菌丝中甘氨酸、丝氨酸、苏氨酸和硫的生物过程、细胞区室、分子功能和代谢。因此，这种生物防治细菌拮抗B. cinerea由于产生了许多作用于细胞中多个靶点的抗真菌物质，因此以多种方式发生。BVFL显着提高番茄叶片抗氧化酶活性，降低番茄灰霉病的发生率，防效为73.12-76.51%。总之，B. velezensis HY19 显示出作为一种强大的抗番茄灰霉病生物制剂的潜力。