Stress-inducible FBS1 family regulates cell division and salt stress tolerance in Arabidopsis thaliana

The F-BOX STRESS INDUCED (FBS) gene family in Arabidopsis thaliana, comprising four members (FBS1-FBS4), is rapidly upregulated in response to various abiotic stresses. Among them, FBS1 is strongly induced by salt stress and preferentially expressed in meristematic tissues, including the shoot apical meristem, root apical meristem (RAM), and vascular cambium. Herein, we demonstrated that FBS1 and its paralogs, FBS2 and FBS3, play important roles in regulating meristem activity and plant responses to salinity stress. Overexpression of FBS genes under the 35S promoter reduced cell division in the RAM and impaired root cap development, resulting in disorganized meristem structure. FBS1 overexpression also increased CYCD6 expression, a key cyclin for cortex layer formation, especially under salt stress. Functional analysis using fbs1-1 knockout and FBS1 overexpression lines revealed that FBS1 positively regulates plant tolerance to salt stress, as evidenced by enhanced growth and survival in overexpressing lines. These findings suggest that FBS1 functions as a stress-responsive regulator that links environmental cues to meristem organization and stress adaptation through ubiquitin-mediated pathways. Our study highlights the FBS gene family as a potential key component in integrating developmental and stress response networks in plants.