The amino acid region from 448-517 of CAMTA3 transcription factor containing a part of the TIG domain represses the N-terminal repression module function.

UNLABELLED

CAMTA3, a Ca-regulated transcription factor, is a repressor of plant immune responses. A truncated version of CAMTA3; CAMTA3 called N-terminal repression module (NRM), and its extended version (CAMTA), which include the DNA binding domain, were previously reported to complement the mutant phenotype. Here, we generated a series of CAMTA3 truncated versions [the N-terminus (aa 1-517), C-terminus (aa 517-1032), R1 (aa 1-173), R2 (aa 174-345), R3 (aa 346-517), R4 (aa 517-689), R5 (aa 690-861) and R6 (aa 862-1032)], expressed in mutant and analyzed the phenotypes of the transgenic lines. Interestingly, unlike CAMTA, extending the N-terminal region to 517 aa did not complement the phenotype, suggesting that the amino acid region from 448-517 (70 aa), which includes a part of the TIG domain suppresses the NRM activity. The C-terminus and other truncated versions (R1-R6) also failed to complement the mutant Expressing the full length or NRM of in plants suppressed the activation of immune-responsive genes and increased the expression of cold-induced genes. In contrast, the transgenic lines expressing the N- or C-terminus or R1-R6 of CAMTA3 showed expression patterns like those of the with enhanced expression of the defense genes and suppressed expression of the cold response genes. Furthermore, like , the transgenic lines expressing the N- or C-terminus, or R1-R6 of CAMTA3 exhibited higher levels of HO and increased resistance to a DC3000 as compared to WT, NRM, or FL-CAMTA3 transgenic plants. Our studies identified a novel regulatory region in CAMTA3 that suppresses the NRM activity.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-023-01401-w.