Molecular Pathogens, 2025, Vol.16, No.4, 159-170 http://microbescipublisher.com/index.php/mp 160 Faced with the severe disease situation, breeding and planting disease-resistant varieties is recognized as the most cost-effective and environmentally friendly strategy for preventing and controlling fungal diseases in wheat. Deeply revealing the molecular basis of wheat disease resistance will not only help to understand the mechanism of plant-pathogen interaction, but also provide genetic resources and technical routes for cultivating broad-spectrum, persistent disease-resistant varieties. Over the past few decades, a series of important progress has been made in the study of the molecular mechanism of wheat disease resistance. On the one hand, a combination of traditional genetics and molecular biology has been used to identify a large number of disease-resistant genes (QTLs) and main-effect genes. On the other hand, with the development of wheat genome sequencing and functional genomics, more and more disease-resistant genes have been cloned, and their coding products and mechanism of action have gradually become clear (Yang et al., 2022). At the same time, the establishment of the theory of innate plant immune provides a framework for wheat disease resistance research. In recent years, it has been found that there are also broad-spectrum resistance mediated by pattern recognition receptors and specific resistance mediated by effector recognition receptors in wheat, which together constitute the wheat immune system. 2 Molecular Genetic Basis of Antifungal Diseases in Wheat 2.1 Types and distribution of disease-resistant genes (Rgenes) Plant disease-resistant genes are groups of genes that can recognize specific pathogens and trigger defense responses. In wheat, there are many types of R genes found, mainly including two major categories: pattern recognition receptors and effector recognition receptors. PRR is usually a membrane receptor kinase/receptor protein that can sense pathogen-associated molecular patterns (PAMPs) and trigger broad-spectrum resistance (Dwivedi et al., 2022), while NLR-like receptors directly or indirectly recognize pathogenic effector proteins in cells, activate specific immunity. As a hexploid, wheat has a huge genome and a very rich R gene. It is estimated that the entire wheat genome contains more than 2 000 NLR gene sequences, 5~6 times that of rice. These genes are distributed in clusters in each subgenome of wheat and have a large number of repetitions and mutations. The traditionally named various wheat disease-resistant main effect genes, such as the Yr series that resist stripe rust, the Lr series that resist leaf rust, the Sr series that resist stalk rust, and the Pm series that resist powdery mildew, are mostly NLR family coded substances. For example, the classic Yr10, Pm3, Sr33 and other genes all encode NBS-LRR proteins in cells and can recognize the effect products of the corresponding rust or vermicelli (Elshafei et al., 2021). 2.2 Evolution and functional differentiation of gene families (such as NLR, PRR) The huge disease-resistant gene family of wheat undergoes repeated amplification and differentiation during its evolution, forming different subfamilies and performing different functions. Taking typical NLR gene examples, wheat NLR can be further divided into TIR-NLR, CC-NLR and other types (depending on the N-terminal domain), but since wheat does not contain TIR-NLR (Toll/IL-1 receptor domain NLR), it is mainly CC-NLR. Between the six subgenomes of the wheat genome, many NLR genes have multiple alleles and orthologous copies. Gene replication and tandem repetition cause some NLR clusters to expand and acquire new specificities through point mutations and recombination, thereby identifying evolving pathogenic effectors. Studies have shown that wheat NLR genes often carry inserted domains, that is, they fuse other functional domains outside the classical LRR structure, which may be used as a "bait" to monitor important targets for pathogenic attacks, thus expanding the scope of NLR recognition. The identified PRRs in wheat include CERK1, a broad bean-like crunchy enzyme activator receptor (which can recognize fungal chitin) and flavonoid auxin receptor FLS2, etc. Although strong PRR-mediated resistance in natural wheat varieties has been rarely reported, studies have shown that the broad-spectrum resistance of wheat to a variety of fungal diseases can be significantly enhanced by overexpressing exogenous or self-PRR. 2.3 Application of genome selection and molecular marker in disease-resistant breeding In wheat disease-resistant breeding, genomic selection and molecular marker-assisted selection (MAS) have become important means. The use of molecular markers can accurately introduce and polymerize disease-resistant
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