Mannose alleviates yellowing process of broccoli florets by regulating chlorophyll catabolism and delaying programmed cell death

The effect of mannose treatment on chlorophyll catabolism and programmed cell death (PCD) in broccoli florets during storage at 20 ℃ has been investigated. The results showed that mannose treatment efficiently restrained chlorophyll degradation in broccoli florets via regulating chlorophyll catabolism genes (BoPPH, BoPAO, BoRCCR, BoSGR1 and BoSGR2). Meanwhile, mannose treatment efficiently suppressed the occurrence of PCD through the mitochondria-dependent pathway in broccoli florets. Less reactive oxygen species content observed in mannose-treated broccoli florets delayed the increase of mitochondrial membrane potential and inhibited unfolding of mitochondria permeability transition pore, which was associated with the inhibition of cytochrome c liberation in mitochondria and the maintenance of high levels of cytochrome c/a and the ratio of Ca2+ content, the activities of cytochrome c oxidase and alternative oxidase . These results suggested that mannose treatment inhibited senescence of broccoli florets through suppressing the chlorophyll degradation and the appearance of PCD.