Resistance and wound-healing activities of broccoli stem during SAS.

Self-adaptive stage (SAS) is defined as the period between harvest and pre-cooling in this study, which is extremely neglected in the field of postharvest horticultural products. This study aimed to investigate resistant responses and wound-healing activities during the SAS. Broccoli heads that needed cut-harvest were used as experimental materials, and the indices related to storage quality, reactive oxygen species, and phenylpropanoid metabolism were determined during 12 h after the harvest. The results showed that the quality of broccoli heads did not change significantly within 12 h after cut-harvest compared with the normal-growth group. The rapid water loss indicated that measures should be taken for water prevention during SAS. The cut-harvest group showed a significant accumulation of H₂O₂ after 3 h, which acted as a signal in regulating the antioxidant enzyme system. The activities of phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, and 4-coumarate coenzyme A ligase increased in cut-harvest broccoli stems during 0–6 h, 3–12 h, and 0–9 h, respectively, compared with those in normal-growth broccoli stems. The enhanced enzyme activity involved in phenylpropanoid metabolism and accumulated phenolic acids associated with wound healing at different time points during SAS demonstrated that the response time should be considered when regulating resistance and wound healing. This study focused on revealing the resistance and wound-healing activities of broccoli stems during independent growth after cut-harvest, thus providing a theoretical basis for the subsequent study and regulatory measurement in cut-harvest vegetables. [ABSTRACT FROM AUTHOR]