A specific homeostasis between callose and H2O2 is needed for an intact BABA-IR against P cucumerina
Abstract: Upon appropriated stimulus plants can activate basal defense mechanisms by reactingfaster and stronger to a biotic challenge reducing the chances for pathogen invasion. Amongmany responses, the production of reactive oxygen species (ROS) and callose deposition are theearliest events in defense. In the present work, we study the ROS and callose interplay duringβ-aminobutyric acid (BABA)-induced priming against the necrotrophic fungus Plectosphaerellacucumerina. Mutants affected in cell redox homeostasis show differences in callose depositions,as well as in basal and induced defense responses. Our findings suggest that PAD2 which encodesthe enzyme that catalizes the first step of the synthesis of glutathion (GSH) plays a revelant rolein basal and induced resistance. On the other hand, the mutant rbohD, which shows low levels ofH2O2, has not altered its basal resistance but is blocked in BABA-IR. In conclusion, our findingsdemonstrate that a specific redox regulation is necessary for BABA-IR against P cucumerinawhich is dependent on PAD2 and RBOHD but not on VTC1 and CAT2.