Analysis of novel volatile compounds, plant-beneficial traits, and genomic features of the endophyte Bacillus velezensis ITCE1 and its crosstalk with Trichoderma

Abstract

The use of agrochemicals is a contributing factor to global climate change, making the development of alternative products urgently needed for sustainable agriculture. Therefore, in this study, we isolated and performed genomic characterization of a plant-beneficial endophytic bacterium, identified as Bacillus velezensis strain ITCE1. In vitro assays confirmed that ITCE1 promotes seed germination, antagonizes fungal pathogens and promotes plant growth under greenhouse conditions (e.g. chlorophyll content, root length, total dry weight). These effects were enhanced by interaction with the beneficial fungus Trichoderma atroviride. The volatile metabolite 2,4-hexadiyne, produced exclusively by ITCE1, consistently increased in abundance from 26.66 % to 94.19 % when Bacillus velezensis was co-cultivated with T. atroviride. This is the first report of 2,4-hexadiyne as a volatile produced by a bacterium with potential biocontrol and plant growth-promoting effects. Additionally, the genome of ITCE1 (4 Mb in size, 46.2 % GC content), its taxonomic affiliation, phylogenetic analyses, and pan-genome profiling with other B. velezensis strains are reported. Finally, genome mining for antimicrobial metabolites revealed the presence of genes involved in the biosynthesis of indole-3-acetic acid, cytokinins, lipopeptides, and siderophores, as well as genes associated with tolerance to osmotic, nitrosative, and other environmental stresses. These findings highlight the broad genetic and functional potential of strain ITCE1 as a bioinoculant for sustainable agriculture.