SlWRKY75 functions as a differential regulator to enhance drought tolerance in tomato (Solanum lycopersicum L.)

Drought poses a significant threat to global food security, necessitating innovations in crop drought tolerance strategies. In this study, we identified a specific transcription factor (TF), SlWRKY75, that exerts opposing regulatory functions in above- and below-ground plant tissues in the tomato. Utilizing CRISPR/Cas9 gene editing technology, two homozygous cr-wrky75 mutant lines were generated to explore the biological functions of SlWRKY75. Our results showed that the SlWRKY75 mutants, compared to wild-type (WT) plants, had a significantly increased number of lateral roots, higher relative water content (RWC), higher chlorophyll content, improved photosynthetic efficiency (F_v/F_m), increased catalase (CAT) activity, and reduced malondialdehyde (MDA) levels under drought conditions, collectively conferring stable drought tolerance across growth stages. Furthermore, SlWRKY75 mutant lines had significantly fewer fruit trichomes compared to WT plants, which was associated with reduced post-harvest water loss and improved post-harvest fruit quality. Through qRT-PCR analysis, along with Y1H and Dual-LUC experiments, this study demonstrates that SlWRKY75 directly binds to the promoters of SlARF5 and SlTRY, thereby inhibiting their expression to mediate differential regulatory functions between aboveground and underground parts. By investigating the multifaceted regulatory functions and mechanisms of plant-specific TFs across different tissues, this study provides targeted strategies for breeding drought-tolerant tomatoes.