Chlorophyll Degradation in Horticultural Crops

One of the symptoms of senescence in harvested horticultural crops is the loss of greenness that comes with the degradation of chlorophyll. With senescence, the chlorophyll-degrading enzyme activities such as chlorophyllase, Mg-dechelatase or Mg-dechelation activity, a new chlorophyll-degrading enzyme, pheophytinase, pheophorbidase and chlorophyll-degrading peroxidase, which are involved in chlorophyll degradation, affected greatly in stored horticultural crops. The chlorophyll derivatives, especially chlorophyllide, pheophytin, pheophorbide and C132-hydroxychlorophyll are accumulated as intermediates of chlorophyll degradation. In addition, chlorophyll degradation by the chlorophyll-degrading enzymes seems to occur in the thylakoid and envelope membrane of chloroplast and/ or the vacuole. The involvement of chlorophyll-degrading enzymes in senescing horticultural crops is also discussed.