To screen endophytic Bacillus producing volatile organic compounds (VOCs) with antifungal activity, and to explore their biocontrol properties toward the growth and pathogenicity of Curvularia lunata. Two-sealed-base-plate assays were used to estimate the antifungal activities of Bacillus strains against C. lunata. Conjoint analysis of solid-phase microextraction gas chromatography-mass spectrometry and antagonistic experiments were used to identify the VOCs responsible for the antifungal activity. Effects of individual synthetic VOCs were analyzed along with reactive oxygen species (ROS) accumulation in C. lunata conidia. After exposure to individual VOCs, conidia were also sprayed onto maize leaves to evaluate their pathogenicity. Expression levels of virulence-related genes in C. lunata mycelium following exposure to VOCs were analyzed using quantitative real-time PCR. Among the ten endophytic Bacillus strains and two plant growth-promoting rhizobacterial (PGPR) strains, only B. subtilis strain DZSY21 strongly inhibited the growth of C. lunata by producing VOCs. 2-Methylbutyric acid, 2-heptanone, and isopentyl acetate produced by strain DZSY21 showed inhibitory effects on the mycelia growth and conidial sporulation of C. lunata. 2-Heptanone and isopentyl acetate also repressed the germination of conidia and the expression levels of virulence-related genes in C. lunata mycelium. Moreover, isopentyl acetate strongly enhanced the accumulation of intracellular ROS in conidia. The disease indexes of maize leaves sprayed with VOC-treated C. lunata conidia were reduced from 60.52 to 26.64%. Endophytic B. subtilis strain DZSY21 displayed the potential to control C. lunata by producing VOCs, especially 2-heptanone and isopentyl acetate.

中文翻译：

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内生枯草芽孢杆菌DZSY21产生的挥发性化合物对弯曲霉的抑菌作用。

筛选具有抗真菌活性的内生芽孢杆菌产生的挥发性有机化合物（VOC），并探讨其对弯孢弯曲菌的生长和致病性的生物防治特性。使用两个密封的底板测定法来估计芽孢杆菌菌株对月球梭菌的抗真菌活性。固相微萃取气相色谱-质谱和拮抗实验的联合分析被用来确定负责抗真菌活性的挥发性有机化合物。分析了单个合成VOC的影响以及月球梭菌分生孢子中的活性氧（ROS）积累。暴露于单独的挥发性有机化合物后，还将分生孢子喷雾到玉米叶片上以评估其致病性。毒力相关基因在C中的表达水平 使用定量实时PCR分析接触挥发性有机化合物后的月球菌丝体。在十个内生芽孢杆菌菌株和两个植物促生根瘤菌（PGPR）菌株中，只有枯草芽孢杆菌DZSY21菌株通过产生VOC强烈抑制月球梭菌的生长。DZSY21菌株生产的2-甲基丁酸，2-庚酮和乙酸异戊酯显示对月球梭菌的菌丝体生长和分生孢子形成有抑制作用。2-庚酮和乙酸异戊酯也抑制分生孢子的萌发和月球梭菌菌丝中毒力相关基因的表达水平。此外，乙酸异戊酯强烈增强了分生孢子中细胞内ROS的积累。VOC处理的月球孢子孢子喷施的玉米叶片的病害指数从60.52％降低至26.64％。内生B.