FERONIA coordinates plant growth and salt tolerance via the phosphorylation of phyB

Phosphorylation modification is required for the modulation of phytochrome B (phyB) thermal reversion, but the kinase(s) that phosphorylate(s) phyB and the biological significance of the phosphorylation are still unknown. Here we report that FERONIA (FER) phosphorylates phyB to regulate plant growth and salt tolerance, and the phosphorylation not only regulates dark-triggered photobody dissociation but also modulates phyB protein abundance in the nucleus. Further analysis indicates that phosphorylation of phyB by FER is sufficient to accelerate the conversion of phyB from the active form (Pfr) to the inactive form (Pr). Under salt stress, FER kinase activity is inhibited, leading to delayed photobody dissociation and increased phyB protein abundance in the nucleus. Our data also show that phyB mutation or overexpression of PIF5 attenuates growth inhibition and promotes plant survival under salt stress. Together, our study not only reveals a kinase that controls phyB turnover via a signature of phosphorylation, but also provides mechanistic insights into the role of the FER-phyB module in coordinating plant growth and stress tolerance. Balance between growth and stress response is critical for plants to adapt to high salinity. This study shows that receptor-like kinase FERONIA takes advantage of phyB-mediated light signalling pathway to coordinate plant growth and salt tolerance.

Automated summary

Phosphorylation modification of phytochrome B (phyB) is essential for its thermal reversion, and this study identifies FERONIA (FER) as the kinase that phosphorylates phyB to regulate plant growth and salt tolerance. The phosphorylation not only regulates dark-triggered photobody dissociation but also modulates phyB protein abundance in the nucleus. The study also reveals that under salt stress, inhibited FER kinase activity leads to delayed photobody dissociation and increased phyB protein abundance in the nucleus, ultimately impacting plant growth and stress tolerance.