Bioscience Methods 2026, Vol.17, No.1, 1-8 http://bioscipublisher.com/index.php/bm 3 with Pseudomonas sp. R41805 and Rhizophagus irregularis MUCL 41833 has been shown to elicit the expression of ethylene response factor 3 (ERF3), which plays a significant role in pathogen defense (Velivelli et al., 2015). This enhancement of the plant's immune response through complex signaling networks involving salicylic acid, jasmonic acid, and ethylene, provides a robust defense mechanism against various pathogens. 3.3 Direct pathogen and pest attack BCAs directly attack pathogens and pests through mechanisms such as hyperparasitism, production of lytic enzymes, and release of antimicrobial compounds. For instance, Bacillus subtilis EG21 produces extracellular lytic enzymes, including cellulase, pectinase, and chitinase. Cellulase degrades the cellulose components in the cell walls of pathogens, disrupting their structural integrity. Pectinase acts by breaking down pectin in plant cell walls, further weakening the pathogen's adhesion to plant tissues. Chitinase is particularly crucial for degrading the main chitin component of fungal cell walls, demonstrating significant effectiveness against fungal pathogens. These enzymes cause extensive damage to the hyphae of Rhizoctonia solani and inhibit the infection of Phytophthora infestans. Experimental results indicate that the lytic enzymes secreted by Bacillus subtilis EG21 significantly inhibited the growth of Rhizoctonia solani in vitro. Microscopic observations revealed marked deformation, swelling, and rupture of the pathogen's hyphae, further confirming the critical role of lytic enzymes in disrupting the structure of the pathogens (Figure 1) (Alfiky et al., 2022). Similarly, microbial biopesticides can produce antimicrobial compounds that inhibit pathogen growth and virulence factors, thereby directly reducing disease incidence. These direct interactions between BCAs and pathogens are crucial for effective biocontrol in potato crops. Figure 1 Representative images for A, potato tuber slices at 4 days postinoculation (dpi) as they were treated with bacterial cells (left), Bacillus subtilis EG21 culture filtrate (middle), and Luria Bertani broth as control (right), and then inoculated with Rhizoctonia solani. B, Lytic enzyme activities in EG21 for cellulase (left) and pectinase (right) (Adopted from Alfiky et al., 2022) 4 Application Strategies for Biocontrol Agents in Potato Cultivation 4.1 Soil and seed treatment Soil and seed treatments are critical strategies for the effective application of biocontrol agents in potato cultivation. These treatments involve the introduction of beneficial microorganisms directly into the soil or onto the seed tubers to suppress soil-borne pathogens and enhance plant health. For instance, Bacillus velezensis K-9 has been shown to significantly reduce potato scab caused by Streptomyces scabies when applied to the soil, leading to improved tuber quality and increased yields (Gush et al., 2023). Similarly, Brevibacillus laterosporus
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