The Molecular Mechanism Of THE1 Function In Plant Defense Against Botrytis Cinerea

The plant cell wall,a highly heterogeneous,complex structure,serves as a dynamic interface between the cell and environmental cues.Plants sense cell wall damage and trigger the cell wall integrity signaling pathway to mediate defense responses against pathogen infection.THESEUS1(THE1),a member of the Catharanthus roseus RLK1-like(CrRLKIL)kinase family,functions as a cell wall integrity sensor that regulates cell elongation during vegetative development.Previous results showed that THE1 plays a role in responses to other cell wall disturbances during biotic stress responses.However,the specific role of THE1 and its downstream factors in defense responses remains to be elucidated.The present investigation reported that THE1 interacts with GUANINE EXCHANGE FACTOR4(GEF4)and that both proteins play regulatory roles in plant resistance to the necrotrophic fungus Botrytis cinerea(B.cinerea).Genetic analysis showed that THE1 and GEF4 function in the same genetic pathway to mediate plant defense responses.In addition,using transcriptome analysis,various genes were identified(such as defense-related,secondary metabolite-related,and transcription factor genes)that are likely downstream targets in the THE1-GEF4 signaling pathway.Moreover,it was found that B.cinerea treatment could induce the endocytosis of THE1,which may likely recycle to the plasma membrane or degrade in the vacuolar.These results suggest that THE1 functions as an upstream regulator of GEF4 signaling to positively regulate defense responses against B.cinerea in Arabidopsis.In conclusion,our results suggest that THE1 functions as an upstream regulator for GEF4 signaling to positively regulate plant response against B.cinerea in Arabidopsis,revealing a surface player for defense against biotic stresses.