Distinct Molecular Pattern-Induced Calcium Signatures Lead to Different Downstream Transcriptional Regulations via AtSR1/CAMTA3.

Plants encrypt the perception of different pathogenic stimuli into specific intracellular calcium (Ca) signatures and subsequently decrypt the signatures into appropriate downstream responses through various Ca sensors. Two microbe-associated molecular patterns (MAMPs), bacterial flg22 and fungal chitin, and one damage-associated molecular pattern (DAMP), AtPep1, were used to study the differential Ca signatures in leaves. The results revealed that flg22, chitin, and AtPep1 induced distinct changes in Ca dynamics in both the cytosol and nucleus. In addition, Flg22 and chitin upregulated the expression of salicylic acid-related genes, and , whereas AtPep1 upregulated the expression of jasmonic acid-related genes, and , in addition to and These data demonstrated that distinct Ca signatures caused by different molecular patterns in leaf cells lead to specific downstream events. Furthermore, these changes in the expression of defense-related genes were disrupted in a knockout mutant of the gene, encoding a calmodulin-binding transcription factor, in which a calmodulin-binding domain on AtSR1 was required for deciphering the Ca signatures into downstream transcription events. These observations extend our knowledge regarding unique and intrinsic roles for Ca signaling in launching and fine-tuning plant immune response, which are mediated by the AtSR1/CAMTA3 transcription factor.