Delaying Broccoli Floret Yellowing by Phytosulfokine α Application During Cold Storage

During postharvest life, broccoli suffers from floret yellowing confining its economic and nutritional value. The objective of the present study was to explore the mechanisms employed by phytosulfokine alpha (PSK alpha) at 150 nM for delaying floret yellowing in broccoli during storage at 4 degrees C for 28 days. Our results showed that the higher endogenous accumulation of hydrogen sulfide (H2S) resulting from the higher gene expression and activities of l-cysteine desulfhydrase (LCD) and d-cysteine desulfhydrase (DCD) in broccoli floret treated with 150 nM PSK alpha may serve as an endogenous signaling molecule for delaying senescence. Moreover, the suppressed ethylene biosynthesis in broccoli floret treated with 150 nM PSK alpha might be ascribed to lower gene expression and activities of ACC synthase (ACS) and ACC oxidase (ACO). Furthermore, lower gene expression and activities of Mg2+ dechelatase (MDC), pheophytinase (PPH), and pheophorbide a oxygenase (PaO) might be the reasons for the higher accumulation of chlorophyll in broccoli floret treated with 150 nM PSK alpha. Based on our findings, exogenous PSK alpha application could be employed as signaling bioactive hormone for retarding floret yellowing of broccoli during storage at 4 degrees C for 28 days.

Automated summary

This study found that treatment with 150nM PSKα increased endogenous accumulation of hydrogen sulfide in broccoli, delaying floret yellowing. Additionally, PSKα suppressed ethylene biosynthesis and reduced chlorophyll degradation, leading to higher chlorophyll accumulation in broccoli florets.