The role of STAY-GREEN in broccoli florets: Insights for improve post-harvest quality

STAY-GREEN (SGR) is a crucial regulator of post-harvest senescence owing to its involvement in chlorophyll (Chl) degradation. In this study, six members of the BoSGR family in broccoli (Brassica oleracea var. italica) were identified. Phylogenetic analysis was used to categorize the genes into three subfamilies: SGR, SGRL, and independent genes. In a transient overexpression experiment conducted on tobacco leaves, all BoSGR members except BoSGR3–2 exhibited the same ability to promote yellowing. Examination of the transcript levels of all six BoSGRs during post-harvest senescence revealed that three genes (BoSGR1, BoSGR3–1, BoSGR7) were significantly upregulated during post-harvest senescence in broccoli florets. Furthermore, after exposure to five different hormones–salicylic acid (SA), methyl jasmonate (MeJA), abscisic acid (ABA), 6-benzylaminopurine (BAP; a synthetic cytokinin), and ethylene-releasing ethephon (ETH), the expression profiles of the three genes were similarly induced by ABA, ETH, and MeJA, but not by SA or BAP. Yellowing and reduction in Chl content in broccoli florets were also promoted by the application of ABA, ETH, and MeJA, but not by SA and BAP. This study offers valuable insights into the roles and expression patterns of BoSGRs in post-harvest senescence and Chl degradation in broccoli florets. These results present potential avenues for enhancing the post-harvest quality of broccoli florets.