Transcriptome analysis offers insights into the mechanisms underlying the induction of resistance against Fusarium root rot in tobacco by Bacillus amyloliquefaciens HN11

Abstract

Tobacco Fusarium root rot has been recognized as the most predominant soil-borne fungal disease in tobacco-growing regions of southern China in recent years, causing extensive damage across a wide area. Bacillus amyloliquefaciens HN11, a biocontrol strain isolated from the rhizosphere of neem, has demonstrated notable efficacy in the rice-tobacco rotation system. It has been observed that HN11 can induce resistance in tobacco against the disease. This study was conducted to investigate the resistance-inducing mechanisms of B. amyloliquefaciens HN11 in tobacco to control Fusarium root rot. These results indicate that the induction of resistance in tobacco by HN11 was predominantly dependent on ethylene and jasmonic acid pathways. In the absence of Fusarium oxysporum JSJ inoculation, jasmonates were indirectly accumulated by HN11 through the activating genes within the alpha-linolenic acid metabolic pathway. When tobacco plants were inoculated with F. oxysporum JSJ, the accumulation and signaling of ethylene were facilitated by HN11 through the upregulation of genes involved in the phytohormone signaling transduction pathway and the MAPK signaling cascade. Additionally, the synthesis of resistance-related substances in tobacco was induced by HN11. Furthermore, upregulation of genes linked to reactive oxygen species signal transduction and local rapid resistance responses were also observed, thereby enhancing the resistance of tobacco to Fusarium root rot disease.