Molecular and phenotypic insights into sulfur’s role in enhancing tomato plant growth, stress tolerance, and productivity

Sulfur is an essential nutrient for plant growth and defense, participating in biochemical processes like gene expression, translation, and redox reactions. While its role in sulfur deficiency has been well studied, the biological responses to sulfur fertilization remain less explored. Here, we investigated these responses by analyzing gene expression in tomato at both hourly and daily intervals following sulfur fertilization. Gene ontology (GO) analysis of differentially expressed genes (DEGs) in response to sulfur fertilization revealed increased expression of genes related to water and wounding responses, as well as cell wall biosynthesis within a day. Weighted gene co-expression network analysis (WGCNA) identified 14 modules linked to time-dependent gene expression changes after sulfur treatment. MAPK and hormone signaling genes peaked within one hour, followed by enhanced molecular expression pathways involved in mRNA transport, ribosome biogenesis, and amino acid biosynthesis. Modules that peaked more than 1 day after sulfur treatment were enriched in processes related to glutathione metabolism, cell division, and auxin and steroid biosynthesis, which are likely to contribute to sustained growth and stress resistance. These findings were validated by increased drought and TYLCV resistance, as well as improved yield in sulfur-fertilized tomato plants, highlighting sulfur fertilization as a strategy for improving agricultural productivity.