Employing phytosulfokine ? (PSK?) for delaying broccoli florets yellowing during cold storage

The yellowing of florets limits the economic and nutritional value of broccoli during postharvest. We investigated mechanisms of action of 150 nM phytosulfokine ? (PSK?) for delaying florets yellowing in broccoli during cold storage. Our results showed that SUMO E3 ligase (SIZ1) gene expression was higher in florets treated with PSK?, which may prevent endogenous H2O2 accumulation, resulting from the higher activity of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase. Besides, higher expression of methionine sulfoxide reductase and cysteine peroxiredoxin genes, concomitant with higher expression of heat shock proteins 70/90 genes, may arise from higher expression of SIZ1 gene. Lower expression and activity of phospholipase D and lipoxygenase may be liable for membrane integrity protection featured by lower malondialdehyde accumulation in florets treated with PSK?. Additionally, florets treated with PSK? exhibited higher endogenous cytokinin accumulation which may arise from higher expression of isopentenyl transferase gene, concomitant with lower expression of cytokinin oxidase gene.

Automated summary

The study found that PSK can delay florets yellowing in broccoli during cold storage by upregulating the expression of SIZ1 gene, reducing endogenous H2O2 accumulation, and increasing the activity of antioxidant enzymes. Additionally, florets treated with PSK showed higher endogenous cytokinin accumulation.