γ-Valerolactone promotes Solanum lycopersicum seedling growth through transcriptomic and plant hormone changes.

There is increasing interest in novel fertilizers to reduce dependency on chemical fertilizers in agriculture. Esters are promising stimulants. γ-Valerolactone, a volatile organic compound produced by Stutzerimonas stutzeri NRCB010, was suggested to promote tomato seedling growth under sterile conditions. We thus examined the effects of varying concentrations of γ-valerolactone on growth in hydroponic and greenhouse conditions, checked associated transcriptional changes, and measured the hormone contents. In this study, γ-valerolactone treatment significantly promote the tomato seedling growth, and the optimum concentration was 100 mg L− 1 and 250 mg L− 1 in hydroponic and greenhouse conditions, respectively. The content of IAA-aspartate, IAA-glutamate, indole-3-acetamide, indole-3-acetonitrile, indole-3-butyric acid, gibberellic acid 3 were all significantly increased in leaves, stem, and roots. Transcriptomic analysis revealed that when treated with γ-valerolactone for 6 h, there are more upregulated differentially expressed genes (DEGs) than downregulated DEGs, however, it’s opposite when treated with γ-valerolactone for 24 h. γ-Valerolactone may stimulate the growth of tomato seedlings through mechanisms such as photosynthesis, phytohormone signaling, and the biosynthesis of secondary metabolites. Our studies provide a theoretical basis for the application of γ -valerolactone as a new type of plant growth regulator and lay the foundation for the development of efficient and environmentally friendly agricultural biostimulants.