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

Amira A E Abdel-Hameed; Kasavajhala V S K Prasad; Anireddy S N Reddy

doi:10.1007/s12298-023-01401-w

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

Physiol Mol Biol Plants. 2023 Dec;29(12):1813-1824. doi: 10.1007/s12298-023-01401-w. Epub 2023 Dec 18.

Authors

Amira A E Abdel-Hameed^{1

2}, Kasavajhala V S K Prasad¹, Anireddy S N Reddy¹

Affiliations

¹ Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1878 USA.
² Present Address: Department of Botany and Microbiology, Faculty of Science, Zagazig University, Zagazig, 44519 Egypt.

Abstract

CAMTA3, a Ca²⁺-regulated transcription factor, is a repressor of plant immune responses. A truncated version of CAMTA3; CAMTA3³³⁴ called N-terminal repression module (NRM), and its extended version (CAMTA⁴⁴⁷), which include the DNA binding domain, were previously reported to complement the camta3/2 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 camta3 mutant and analyzed the phenotypes of the transgenic lines. Interestingly, unlike CAMTA⁴⁴⁷, extending the N-terminal region to 517 aa did not complement the camta3 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 camta3 mutant. Expressing the full length or NRM of CAMTA3 in camta3 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 camta3 with enhanced expression of the defense genes and suppressed expression of the cold response genes. Furthermore, like camta3, the transgenic lines expressing the N- or C-terminus, or R1-R6 of CAMTA3 exhibited higher levels of H₂O₂ and increased resistance to a Pst 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.

Keywords: Biotic stress; CAMTA3; N-terminal repression module; Plant immunity; Transcription factor immunoglobin; Transcriptional activity.

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