Abstract
The ascorbate content declined rapidly in broccoli (Brassica oleracea L. var. italica) florets during postharvest senescence. In this study, ascorbate peroxidase (APX), ascorbate oxidase (ASO), L-galactono-1,4-lactone dehydrogenase (GLDH), ascorbate free radical reductase (AFRR), dehydroascorbate reductase (DHAR) and glutathione reductase (GSH) were investigated in enzyme activities and gene expression after harvest and treatments with plant hormones. It is observed that mRNA levels of chloroplastic APX (BO-sAPX and BO-tbAPX) decreased greatly within 12 h after harvest in broccoli florets. In addition, as a result of the suppression of other chloroplastic genes involved in ascorbate synthesis (BO-AFRR 1 and BO-DHAR), active oxygen species accumulation and ascorbate degradation may have been accelerated in chloroplasts. We also found that the mRNA expression of GLDH and chloroplastic genes involved in ascorbate metabolism was suppressed by the treatments with methyl jasmonate and ABA.
