Combining transcriptomics and Genome-wide identification to characterize the SlACS gene family and uncover the drought tolerance role of SlACS29 in tomato

Tomato is highly susceptible to drought stress, and improving its tolerance drought resistance is the key to maintaining the high-yield goal. In this study, 45 SlACS (1-aminocyclopropane-1-carboxylic acid synthase) genes were identified in the tomato genome, and one member, SlACS29, was selected for functional analysis in drought response. Bioinformatic characterization (gene structure, conserved motifs, and promoter cis-elements) and expression profiling (reanalysis of transcriptomic data and Quantitative Real-Time PCR (qRT-PCR)) revealed that many SlACS genes respond to abiotic stresses, with SlACS29 showing especially strong induction by drought. The SlACS29 protein was found to localize to chloroplasts. Using virus-induced gene silencing (VIGS), we demonstrated that silencing SlACS29 compromises drought tolerance in tomato: silenced Plants exhibited faster wilting and significantly lower leaf water content under drought, along with reduced superoxide dismutase and catalase activities, higher malondialdehyde accumulation, and elevated Reactive Oxygen Species (ROS) levels and chloroplast damage, compared to control Plants. Silencing SlACS29 also altered the expression of ethylene biosynthetic genes (such as ACC oxidase). These findings establish SlACS29 as a positive regulator of drought tolerance in tomato, likely through modulating ethylene production and ROS homeostasis, and offer a potential genetic target for improving stress resistance in tomato.

Abiotic stresses; Function analysis; SlACS gene family; SlACS29; Tomato (Solanum lycopersicum).