Research on the Growth-Promoting Effect of Bacillus velezensis HE-23 Strain on Tomatoes

Abstract

Abstract An increasing amount of attention has been directed towards beneficial microorganisms capable of producing bioactive substances, which can promote the growth of crops and enhance their defense mechanisms. This study focused on the growth-promoting effects of Bacillus velezensis HE-23, isolated from the roots of Aucklandia lappa, on tomatoes (Solanum lycopersicum L.). The growth-promotion experiments indicated that the fermentation broth of HE-23 significantly facilitated tomato seed germination and seedling growth. Specifically, the root length, above-ground dry weight, below-ground fresh weight, and below-ground dry weight were enhanced by 68.08, 80.08, 84.03, and 70.65%, respectively. In-depth analysis revealed that the fermentation broth of HE-23 could induce the expression of genes associated with the gibberellin (GA), indole-3-acetic acid (IAA), and mitogen-activated protein kinase (MAPK) cascade signaling pathways. Notably, the expression levels of SlFZY1, SlGA3ox2, and SlGA20ox2 were upregulated by 2.73, 2.99, and 5.3 fold respectively. These findings provide crucial insights into the growth-promoting mechanism of the HE-23 strain, and also lay a substantial foundation for its development as a microbial inoculant for vegetable and fruit crops.