MicroRNA-mediated immunity in rice
The miR393 is the first disease resistance-associated miRNA to be identified in Arabidopsis against the bacterial flagellin peptide flg22, which is an example of a PAMP molecule (Navarro et al.2006; Li et al. 2010). The miR393 confers resistance toPseudomonas syringae pv. tomato by targeting TIR1(transport inhibitor response 1) and AFB2 /AFB3 A (auxin signaling F-Box proteins 2 and 3). These genes are involved in hormone-mediated growth-defence trade-offs through the suppression of auxin signalling (Navarro et al. 2006). This study clearly established a link between miRNAs and plant immunity. Apart from response to bacterial disease, miR393 has also been shown to involve in leaf and root development (Chen et al. 2011; Si-Ammouret al. 2011) and resistance to various abiotic stresses inArabidopsis (Vidal et al. 2010; Chen, Li & Xiong 2012; Iglesias et al. 2014; Denver & Ullah 2019). Further studies in rice, Osa-miR393 regulates flag leaf angle, plant height, primary root length, seed germination and seedling development, sensitivity to auxin, reduced tolerance to salt and drought (Bian et al. 2012; Xia et al. 2012; Guo et al. 2016). The role of miRNAs in mediating resistance response to various pathogen and herbivores is discussed in subsequent section (Table 1, Figure 1).