Hydrogen sulfide promotes flowering in heading Chinese cabbage by S-sulfhydration of BraFLCs

Abstract

AbstractHeading Chinese cabbage (Brassica rapaL. syn.B.campestrisL. ssp.chinensisMakino var.pekinensis(Rupr.) J. Cao et Sh. Cao) is a cruciferousBrassicavegetable that has a triplicate genome, owing to an ancient genome duplication event. It is unclear whether the duplicated homologs have conserved or diversified functions. Hydrogen sulfide (H2S) is a plant gasotransmitter that plays important physiological roles in growth, development, and responses to environmental stresses. The modification of cysteines through S-sulfhydration is an important mechanism of H2S, which regulates protein functions. H2S promotes flowering inArabidopsisand heading Chinese cabbage. Here we investigated the molecular mechanisms of H2S used to promote flowering in the latter. Four, five, and fourBraFLC,BraSOC I, andBraFThomologs were identified in heading Chinese cabbage. Different BraFLC proteins were bound to different CArG boxes in the promoter regions of theBraSOC IandBraFThomologs, producing different binding patterns. Thus, there may be functionally diverseBraFLChomologs in heading Chinese cabbage. Exogenous H2S at 100 μmol L−1significantly promoted flowering by compensating for insufficient vernalization. BraFLC 1 and BraFLC 3 underwent S-sulfhydration by H2S, after which their abilities to bind mostBraSOC IorBraFTpromoter probes weakened or even disappeared. These changes in binding ability were consistent with the expression pattern of theBraFTandBraSOC Ihomologs in seedlings treated with H2S. These results indicated that H2S signaling regulates flowering time. In summary, H2S signaling promoted plant flowering by weakening or eliminating the binding abilities of BraFLCs to downstream promoters through S-sulfhydration.