Abstract
Hydrogen peroxide (H(2)O(2)) is relatively stable among ROS (reactive oxygen species) and could act as a signal in plant cells. In the present work, detached tomato leaves were treated with exogenous H(2)O(2) at 10 mmol/L for 8 h to study the mechanism of how H(2)O(2) regulates leaf senescence. The data indicated that H(2)O(2) treatment significantly accelerated the degradation of chlorophyll and led to the upregulation of the expression of leaf senescence-related genes (NYC1, PAO, PPH, SGR1, SAG12 and SAG15) during leaf senescence. H(2)O(2) treatment also induced the accumulation of H(2)O(2) and malondialdehyde (MDA), decreased POD and SOD enzyme activities and inhibited H(2)S production by reducing the expression of LCD1/2 and DCD1/2. A correlation analysis indicated that H(2)O(2) was significantly and negatively correlated with chlorophyll, the expression of leaf senescence-related genes, and LCD1/2 and DCD1/2. The principal component analysis (PCA) results show that H(2)S showed the highest load value followed by O(2)(•-), H(2)O(2), DCD1, SAG15, etc. Therefore, these findings provide a basis for studying the role of H(2)O(2) in regulating detached tomato leaf senescence and demonstrated that H(2)O(2) plays a positive role in the senescence of detached leaves by repressing antioxidant enzymes and H(2)S production.