Nature Plants | Transcription Regulation Mechanism of Plant Early Immune Response

Responsible editor | When facing the invasion of pathogenic organisms from the outside world, the plant will perceive the molecular patterns (PAMPs or DAMPs) derived from microorganisms or plants through the pattern recognition receptors located on the surface of plant cells, thereby inducing patterns to trigger immune PTI Happened [1].

Although many types of PRR receptors and corresponding ligands have been identified [2], it is still unclear how plants recognize different types of ligands from different sources and whether they produce different immune export mechanisms.

A large number of transcriptional regulatory events will occur during the PTI process [3].
Some reports have analyzed and compared the data of transcriptional responses triggered by 2-3 pathogenic molecules.
However, due to the experimental scale and conditions, the results of comparative analysis may exist.
limitation.

On March 15, the research team of Cyril Zipfel, a well-known plant immunologist, published a research paper entitled The transcriptional landscape of Arabidopsis thaliana pattern-triggered immunity in Nature Plants online.

By comparing the transcriptome data of Arabidopsis thaliana processed by seven molecular patterns at different times in the early stage, this study revealed the common and specific characteristics of the early immune signal transcription response induced by different molecules, and identified new plant immune components.
.

In order to determine the time between transcription reactions triggered by molecular patterns and the degree of recognition, the researchers selected 7 molecular patterns with known PRRs, namely 3-OH-FA, flg22, elf18, nip20, CO8, OGs and Pep1.
They are derived from bacteria, fungi, oomycetes, and plants, including fatty acids, peptides, and polysaccharides, and their receptors have been identified (Figure 1).Each molecular model was used to process wild-type and corresponding PRR mutants.
Samples were collected at 0, 5, 10, 30, 90, and 180 minutes after treatment for transcriptome sequencing, and differentially expressed genes (DEGs) were extracted.

The results showed that there were 10730 DEGs (5718 up-regulated genes, 5012 down-regulated genes), the most DEG obtained by flg22 treatment (8451 DEG; 4816 up-regulated genes, 3635 down-regulated genes), the difference obtained by 3-OH-FA treatment The fewest genes (1633 DEG; 1246 up-regulated genes, 387 down-regulated genes).

Except for the more specific differential genes obtained by flg22 treatment, the differential genes of the other groups are consistent, indicating that the genes induced in the early plant immune response are universal, but the induction speed of these differential genes is different .

In order to identify the transcription factors that regulate these genes, the researchers further classified the up-regulated genes according to time and analyzed the cis-acting elements.
It was found that a large number of CAMTA transcription factor binding elements were enriched in the up-regulated genes in the first 10 minutes, and 10 minutes after treatment.
The up-regulated genes induced by -30 minutes enriched the WRKY binding sites.

This is consistent with the important role of WRKY and CAMTA in PTI.

Since CAMTA is the main transcriptional regulator of plant GSR (Universal Stress Response) [4], the authors analyzed a series of data sets of abiotic stress responses in Arabidopsis and found that many genes that are induced by molecular patterns most rapidly and most commonly upregulated are also It is induced by abiotic stress, which indicates that the early transcriptional response of plants to molecular patterns is part of plant GSR, indicating that plant cells are consistent in responding to different stresses.

Figure 1 Schematic diagram of molecular model and distribution of induced differentially expressed genes.
The author also identified 39 specific differential genes induced by molecular model (core immunity response, CIR), of which the most prominently expressed type of gene GLRs encodes glutamate receptor protein , As a calcium permeable channel in Arabidopsis thaliana to participate in the injury response [5,6], its role in the immune response has not been reported.The authors used CRISPR-Cas9 to construct glr2.
7/2.
8/2.
9 triple mutants and found that the mutants were not sensitive to the increase in calcium concentration induced by molecular patterns, and were more sensitive to pathogenic bacteria, proving that GLR 2.
7/2.
8/2.
9 plays an important role in PTI effect.

Combining with previous research on the role of CNGCs in immune response by the authors, the authors found that multiple channels of the Arabidopsis family, such as CNGCs, OSCAs, and GLRs, all play a role in the calcium response induced by plant molecular models.

In summary, this article conducts a comprehensive analysis of transcriptome data at multiple time points induced by multiple molecular patterns, reveals the commonality and specificity of transcription events in the early immune response of plants, and identifies new plant immune responses Important component.

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