SlWRKY6 Mediates H2S Signaling and SlGRF1-SlGIF2 Module to Coordinately Regulate Plant Growth, Fruit yield and Ripening in Tomato.
Hydrogen sulfide (H2S), a gaseous signaling molecule, retards plant senescence and fruit ripening via protein persulfidation. However, the molecular mechanism underlying its coordination of fruit ripening with plant growth and development remains undefined. This study found that H2S could delay tomato fruit ripening and leaf senescence, and H2S defective mutant sllcd1 shows premature fruit ripening and stunted growth. Overexpression of SlWRKY6, which could be persulfidated by H2S, promotes fruit ripening and reduces fruit number. Molecular assays demonstrated that SlWRKY6 directly binds to the promoter of SlGIF2, a transcriptional co-activator, to repress its expression. Notably, H2S attenuates the repressive effect through persulfidation of SlWRKY6 to increase SlGIF2 transcription. Furthermore, SlGIF2 physically interacts with the GROWTH-REGULATING FACTOR 1 (SlGRF1). Functional validation showed that SlGRF1-SlGIF2 complex serves as a positive regulator of tomato plant growth and fruit yield while concomitantly delaying fruit ripening. Conversely, slgrf1 gene-edited mutants exhibit reduced plant growth, fruit yield and accelerated ripening. Mechanistically, SlGRF1-SlGIF2 complex synergistically activates two downstream target genes: SlCYCD3;1, a key cell-cycle regulator required for cell proliferation and plant growth, and SlCBSX5, which encodes an H2S biosynthesis enzyme that retards fruit ripening. This study provides a module that SlWRKY6-SlGRF1-SlGIF2 integrates H2S signal and genetically coordinates plant growth, fruit yield and fruit ripening in tomato.