AUTHOR=Xuan Zhe , Wang Yu , Shen Yuying , Pan Xiao , Wang Jiatong , Liu Wenbo , Miao Weiguo , Jin Pengfei 

TITLE=Bacillus velezensis HN-2: a potent antiviral agent against pepper veinal mottle virus

JOURNAL=Frontiers in Plant Science

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1403202

DOI=10.3389/fpls.2024.1403202

ISSN=1664-462X

ABSTRACT=<sec><title>Background</title><p>Pepper veinal mottle virus (PVMV) belongs to the genus <italic>Potyvirus</italic> within the family Potyviridae and is a major threat to pepper production, causing reduction in yield and fruit quality; however, efficient pesticides and chemical treatments for plant protection against viral infections are lacking. Hence, there is a critical need to discover highly active and environment-friendly antiviral agents derived from natural sources. <italic>Bacillus</italic> spp. are widely utilized as biocontrol agents to manage fungal, bacterial, and viral plant diseases. Particularly, <italic>Bacillus velezensis</italic> HN-2 exhibits a strong antibiotic activity against plant pathogens and can also induce plant resistance.</p></sec><sec><title>Methods</title><p>The experimental subjects employed in this study were <italic>Bacillus velezensis</italic> HN-2, benzothiadiazole, and dufulin, aiming to evaluate their impact on antioxidant activity, levels of reactive oxygen species, activity of defense enzymes, and expression of defense-related genes in Nicotiana benthamiana. Furthermore, the colonization ability of <italic>Bacillus velezensis</italic> HN-2 in Capsicum chinense was investigated. </p></sec><sec><title>Results</title><p>The results of bioassays revealed the robust colonization capability of <italic>Bacillus velezensis</italic> HN-2, particularly in intercellular spaces, leading to delayed infection and enhanced protection against PVMV through multiple plant defense mechanisms, thereby promoting plant growth. Furthermore, <italic>Bacillus velezensis</italic> HN-2 increased the activities of antioxidant enzymes, thereby mitigating the PVMV-induced ROS production in <italic>Nicotiana benthamiana</italic>. Moreover, the application of <italic>Bacillus velezensis</italic> HN-2 at 5 dpi significantly increased the expression of JA-responsive genes, whereas the expression of salicylic acid-responsive genes remained unchanged, implying the activation of the JA signaling pathway as a crucial mechanism underlying <italic>Bacillus velezensis</italic> HN-2-induced anti-PVMV activity. Immunoblot analysis revealed that HN-2 treatment delayed PVMV infection at 15 dpi, further highlighting its role in inducing plant resistance and promoting growth and development. </p></sec><sec><title>Conclusions</title><p>These findings underscore the potential of <italic>Bacillus velezensis</italic> HN-2 for field application in managing viral plant diseases effectively. </p></sec>