A B S T R A C T
During dark-induced senescence at 12-14 °C, changes of endogenous hydrogen sulfide (H25) metabolism
chlorophyll degradation, energy status, and antioxidant capacity of lpomoea aquatica fumigated with ot
without exogenously applied H25 donor sodium hydrosulfide (NaHS) were assessed. Compared to the
control, NaHS 'treatment brought about higher contents of endogenous H25 and chlorophyll, both of
Which Were matched With increased activities of'H25 synthetic enzymes and decreased activities of
chlorophyll-degrading enzyme. Electron microscopy confirmed that the breakdown of chloroplasts was
reduced by NaHS. H25 not only sustained the energy status, but also decreased the respiration rate and
increased antioxidant capacity. The inhibition of H25 production caused by the application ofits synthetic
inhibitor (DL-propargylglucine) aggravated the yellowing of I. aquatica, and this response could be
rescued by exogenously applied NaHS. Nevertheless, no obvious differences were observed between
treatment of hypotaurine (a scavenger' of H25) and control. These results suggest that NaHS fumligatégitll;
induced endogenous H25 might improve the energy status. leading to elahancemeergcsigptégzztica.
Capacity and inhibition Of the Fespimtlon rate, and ConSequentIyéliglugllgidviisghiidl rights reserved.