Molecular Microbiology Research, 2025, Vol.15, No.2, 82-92 http://microbescipublisher.com/index.php/mmr 86 horizontal resistance QTL loci such as pi21 and Pb1 (Fukuoka et al., 2009; Inoue et al., 2013). The mechanism of disease resistance genes in initiating immune responses is relatively complex. When pathogens invade, PRRs (such as FLS2 and Xa21) first recognize pathogen-associated molecular patterns (PAMPs), activate MAPK cascades and calcium channels, and further trigger reactive oxygen species (ROS) outbreaks; at the same time, NLR proteins can sense effectors secreted by pathogens, activate effector-triggered immune (ETI) responses, and strengthen immune responses (Figure 1). The above signals are further amplified through hormone pathways (such as salicylic acid SA and jasmonic acid JA), and ultimately through the regulation of transcription factors such as WRKY, ERF, and NAC, defense-related gene expression and programmed cell death and other resistance responses are initiated (Ofori et al., 2025). For example, the broad-spectrum blast resistance gene Pb1 interacts with the transcription factor OsWRKY45 to activate the expression of SA pathway-related genes, thereby improving resistance to bacterial blight and rice blast (Inoue et al., 2013). In addition, genes such as OsERF922 and OsNAC4 also participate in the immune regulatory network of various diseases by regulating defense genes or cell death signals (Kaneda et al., 2009; Wang et al., 2016). It is worth noting that these resistance mechanisms not only involve gene recognition functions, but also integrate hormone signal transduction, redox balance regulation, epigenetic regulation and the participation of non-coding RNA, forming a complex network of progressive and mutually regulated layers. Current research is gradually shifting to the discovery of functional regulatory factors in order to achieve a coordinated balance between disease resistance and growth traits, and provide more efficient and stable genetic tools for resistance breeding (Li et al., 2021). Figure 1 Molecular approaches for rice breeding, including conventional breeding, marker-assisted selection (MAS), and transgenic technology, to develop disease-resistant rice varieties (Adopted from Ofori et al., 2025)
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