Molecular Pathogens, 2025, Vol.16, No.4, 159-170 http://microbescipublisher.com/index.php/mp 163 usually exceeds 200 nt in length and does not encode proteins, but can regulate gene expression through a variety of mechanisms. In recent years, some plant lncRNAs have been found to participate in immunity as "miRNA sponges" or transcriptional co-regulators. For example, several inducible lncRNAs were identified in rice and tomatoes that bind to specific miRNAs, reducing the inhibition of miRNAs against disease-resistant genes, thereby increasing the expression of disease-resistant-related genes. 4.3 The role of epigenetic regulation in the formation of disease resistance Epigenetic regulation refers to the mechanism that can genetically affect gene expression without changing the DNA sequence, including DNA methylation, histone covalent modification, chromatin remodeling, etc. In plant disease resistance response, epigenetic regulation shapes the durability and strength of disease resistance by affecting the activity of key genes. DNA methylation is one of the important apparent markers, usually occurring on cytosine (C) in the gene promoter or coding region. High methylation levels often cause chromatin aggregation and gene transcription to be blocked. Studies have shown that pathogen infection may cause demethylation of promoters of certain genes in plants, thereby inducing resistance-related gene expression. For example, NPR1, the regulatory gene of the salicylic acid (SA) pathway, undergoes promoter demethylation when Arabidopsis is attacked by bacteria, resulting in its transcriptional upregulation and enhancing the anti-disease response. It has been reported that the methylation levels of certain defense gene promoters in wheat gibberellia-resistant varieties are lower than those in sensory varieties, indicating the correlation between hypomethylation and high expression. Histone modification is another layer of regulation. For example, modifications such as acetylation and methylation can change the structure of chromatin and affect gene transcriptional activity. In anti-disease responses, histone acetylation is often associated with gene activation (Singh et al., 2022). A recent study identified the role of wheat histone acetyltransferase TaHAG1 in anti-powdery disease: TaHAG1 interacts with the transcription factor TaPLATZ5 to ethylate the histone of TaPAD4, a key gene in the adversarial signaling pathway, enhancing transcription of the gene (Song et al., 2022). The results show that increasing TaHAG1 activity can promote wheat to produce a stronger anti-powdery response (Figure 1). Figure 1 Histone acetyltransferase TaHAG1is responsible for powdery mildew resistance in wheat (Adopted from Song et al., 2022) Image caption: (a) Ten-day-old TaHAG1-KO, TaHAG1-RNAi, TaHAG1-OE and wild-type (WT) Fielder plants were inoculated with Bgt isolate E09. Representative leaves were removed and photographed at 9 d post-inoculation (dpi). Bar, 3 mm. (b) Trypan blue staining of the leaves infected with Bgt E09 at 9 dpi to visualize fungal structures and plant cell death. Bar, 50 μm. (c) Trypan blue-DAB staining of leaves infected with Bgt E09 at 2 dpi. Brown staining shows the accumulation of H2O2. Bar, 50 μm (Adopted from Song et al., 2022)
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