Systemic acquired resistance (SAR) is a crucial defense mechanism in plants, which can significantly enhance the plant's resistance to pathogenic microorganisms. SAR has systemic, persistent, and broad-spectrum characteristics, whose transcriptional regulation plays a central role in the process. Here, the research progress on transcriptional regulation of SAR from the synthesis of SA, Pip/NHP, transcriptional regulation of NPR1, NPR3/NPR4 receptors and Pip/NHP mobile signals, as well as TGA, WRKY transcription factor family regulation was reviewed, providing a reference for a deeper understanding of plant immune regulatory networks, and systematic exploration of the mechanisms by which plants balanced growth and defense in complex environments.

Rice (Oryza sativa) is one of the most vital food crops globally, and its yield plays a crucial role in ensuring food security. However, various diseases affecting rice pose significant threats to this security. Among these, rice blast, bacterial blight, and sheath blight are the three predominant diseases impacting global rice production. Consequently, there is an urgent need to breed and cultivate rice varieties with broad-spectrum disease resistance. In recent years, substantial advancements have been made in understanding the regulatory mechanisms underlying disease resistance in rice. This paper reviews these mechanisms from multiple perspectives, including the plant’s intrinsic immune responses and the functional dynamics of resistance genes. Furthermore, it highlights pressing issues that require immediate attention to facilitate broad-spectrum disease-resistant breeding efforts for rice.

SUMOylation is a crucial post-translational modification in plants, playing a pivotal role in plant immune regulation by mediating substrate protein functions, the activation and transduction of immune signals, and hormonal signaling networks. This review systematically summarizes recent research advances in SUMOylation during plant-pathogen interactions, focusing on the enzymatic cascade mechanisms of the SUMOylation system, the involvement of SUMOylation in plant immune regulation, and the manipulation of the SUMOylation system by pathogen effector proteins. This review aims to decipher the SUMOylation-mediated regulatory network of plant immunity and to provide reference for developing novel disease resistance strategies in crops based on SUMO modification.

Verticillium wilt, caused by Verticillium dahliae, is one of the most major threats in cotton production, which can lead to a significant reduction of cotton yield and fiber quality. Our research team previously conducted a transcriptomic analysis on Arabidopsis thaliana inoculated with V. dahliae and discovered that the gene AT3G53980.2, which encodes the DIR1-like protein, was strongly induced by the pathogen. In this study, we discovered that the cotton lipid transfer protein gene GhDIR1 (Gh_A09G180700.1) displays high homology with AT3G53980.2. Bioinformatic analysis indicated that the open reading frame (ORF) of GhDIR1 is 351 bp, encoding 116 amino acids. The subcellular localization analysis using transient expression displayed that GhDIR1 was shown to be localized to the cell membrane. Quantitative real-time PCR (qRT-PCR) analysis determined that GhDIR1 expression was rapidly induced by V. dahliae. Virus-induced gene silencing revealed that downregulation of GhDIR1 significantly increased cotton susceptibility to V. dahliae. Further analysis through transcriptomic sequencing of wild-type and GhDIR1-silenced plants revealed that differentially expressed genes were primarily enriched in pathways related to "flavonoid biosynthesis","sesquiterpene and triterpene biosynthesis" and "α-linolenic acid metabolism". The expression levels of marker genes (GhCHS, GhDFR, GhCAD, GhSEQ, GhLOX, and GhAOC) involved in three pathways were downregulated. This data suggests that GhDIR1 contributes to the synthesis of protective compounds. We propose that GhDIR1 may mediate the synthesis of flavonoids and terpenoids, regulate the secondary metabolism of plant hormones such as jasmonic acid (JA), and activate related signaling pathways. These results suggested that GhDIR1 might act as a positive regulatory factor and modulate immune defense responses through its regulation in multiple hormone and resistance signaling networks against Verticillium wilt in cotton.

INTRODUCTION: Bacterial blight is one of the three major diseases that threaten global rice production, seriously affecting the yield and quality of rice. The identification and utilization of resistance genes is one of the most effective ways to control bacterial blight. 

RATIONALE: To identify quantitative trait locus (QTL) related to bacterial blight resistance in rice, this study used the indica rice HZ, the japonica rice Nekken2 and their 120 recombinant inbred lines (RILs) as experimental materials. Four different pathotypes of bacterial blight were inoculated at the tillering stage of rice and the resistance phenotypes were evaluated. 

RESULTS: Based on the high-density genetic map constructed previously, 19 QTLs were detected, with the maximum limit of detection (LOD) value being 5.49. Candidate genes within the detected QTL intervals were screened and their expression levels were analyzed by qRT-PCR. LOC_Os02g13410 and LOC_Os04g01320, which are related to the regulatory pathway of STK receptor protein, showed significant upregulated expression after inoculation treatment. Meanwhile, the expression levels of the MYB transcription factor family gene LOC_Os05g10690 and the gene LOC_Os01g12320 related to the lipase regulatory pathway of GDSL-like lipase/acylhydrolase showed an extremely significant increase after inoculation treatment. The expression levels of the candidate genes LOC_Os02g13270, LOC_Os02g13410, LOC_Os02g13420, LOC_Os02g13430 and LOC_Os01g12130 were significantly different between the two parents and were induced after inoculation with the bacterial blight pathogen. 

 CONCLUSION: It was found that these candidate genes are presumed to be key candidate genes for regulating resistance to bacterial blight. The above results lay a foundation for the fine mapping and cloning of bacterial blight resistance-related genes and are of great significance for breeding rice varieties with broad-spectrum resistance to diseases.

The plant cell wall, composed of cellulose, hemicellulose, pectin and lignin, is a dynamically changing network structure, which not only plays the role of a key line of defence in the process of plant resistance to external pressure and adaptation to environmental changes, but also plays the role of an information hub in the process of signal transmission. When the cell wall is damaged, cells sense cell wall changes and make early immune responses, such as hormonal changes, alterations in wall composition and modifications, and the production of disease-resistant secondary metabolites. Although the importance of the cell wall in plant immunity is widely recognised, the specific molecular mechanisms by which cell wall damage triggers immune responses remain poorly understood. The application of in situ unlabelled imaging techniques in plant cells is gradually increasing and has become an important tool for studying cell wall structure and function. This paper describes the interaction mechanism between plant cell wall and immune response to provide a scientific basis for a deeper understanding of plant life activities and improve crop disease resistance, and describes in situ non-labelled imaging of the cell wall to provide more technological options for advancing the study of the cell wall in immune response.

INTRODUCTION: The phytohormone salicylic acid (SA) plays various important roles in plants, such as disease resistance, seed germination, and leaf senescence. Among them, the roles of SA in plant disease resistance are most well-studied. Since SA promotes disease resistance at the cost of plant growth, plants need to dynamically regulate the content of SA to balance disease resistance and growth. Therefore, measurement of SA content is an important aspect in plant immunity study. 

RATIONALE: High-performance liquid chromatography (HPLC)-fluorescence detector is the most commonly used method for the quantitative measurement of SA. In order to improve the efficiency and sensitivity of current methods, this study optimized the composition, ion concentration, and pH of the mobile phase, and the detection wavelength and detection procedure. 

RESULTS: The baseline of the chromatogram was more stable when acetonitrile instead of methanol was used in the mobile phase. When the pH of the mobile phase was 5.2, the retention time of SA was short, and there was no interference peak near the SA peak, which was favorable to shorten the detection time. The higher concentration of sodium acetate (100 mmol·L-1) in the mobile phase was better than that of lower concentration (20~50 mmol·L-1). Wavelength scanning revealed that the optimal excitation wavelength was 300 nm and the optimal emission wavelength was 405 nm, which improved the sensitivity of the detection of SA. At a flow rate of 2 mL·min-1, it took 3.5 min for elution, 3.5 min for column wash, and 3 min for column balance, shortening the measurement of one sample to 10 min. 

CONCLUSION: These optimizations greatly improved the sensitivity, stability, and efficiency of the SA measurement, which will contribute to the plant immunity research.