Broccoli STAY-GREEN 3–2 (BoSGR3-2) acts as a negative regulator, mitigating chlorophyll degradation triggered by other BoSGRs

STAY-GREEN (SGR) plays a pivotal role in chlorophyll (Chl) degradation owing to its interaction with photosystem proteins and its role as a Chl catabolic enzyme. We previously found that three broccoli SGRs (BoSGR1, BoSGR3-1, and BoSGR7) were positive regulators of Chl degradation. In this study, BoSGRs were localized to the chloroplasts, where BoSGR3-2 inhibited Chl degradation induced by three BoSGRs in tobacco. Furthermore, BoSGR3-2 was shown to interact with three BoSGRs in vitro and in vivo using yeast two-hybrid, GST pull-down, and co-immunoprecipitation assays. Our results indicated that BoSGR3-2 may inhibit Chl degradation through interactions with the three BoSGRs.