2,4-Epibrassinolide delays leaf senescence in pak choi (Brassica rapa subsp. chinensis) by regulating its chlorophyll metabolic pathway and endogenous hormones content

• EBR decreased the degradation of Chl and its derivatives. • EBR reduced the activity of Chl degradation pathway related enzymes. • EBR decreased the expression of Chl degradation related genes. • EBR reduced the JA and ABA accumulation in pak choi.