Malus hupehensis miR168 Targets to ARGONAUTE1 and Contributes to the Resistance against Botryosphaeria dothidea Infection by Altering Defense Responses

Abstract

MicroRNA (miRNA)-mediated post-transcriptional regulation plays a fundamental role in various plant physiological processes, including responses to pathogens. MicroRNA168 has been implicated as an essential factor of miRNA pathways by targeting ARGONAUTE1 (AGO1), the core component of the RNA-induced silencing complex (RISC). A fluctuation in AGO1 expression influences various plant-pathogen interactions, and the homeostasis of AGO1 and miR168 accumulation is maintained by a complicated feedback regulatory loop. In this study, the connection between miR168 and the resistance of Malus hupehensis to Botryosphaeria dothidea is revealed. The induction of both the mature miR168 and its precursor in plants subjected to B. dothidea infection indicate the transcriptional activation of MIR168a. MIR168a promoter analysis demonstrates that the promoter can be activated by B. dothidea and salicylic acid (SA). However, the direct target of miR168, M. hupehensis ARGONAUTE1 (MhAGO1), is shown to be induced under the infection. Expression and transcription activity analysis demonstrate the transcriptional activation and the post-transcriptional suppression of MhAGO1 in response to B. dothidea infection. By inhibiting reactive oxygen species (ROS) production and enhancing SA-mediated defense responses, miR168a delays the symptom development of leaves inoculated with B. dothidea and impedes the pathogen growth, while MhAGO1 is found to have the opposite effects. Collectively, these findings suggest that the expression of miR168 and MhAGO1 in M. hupehensis in response to B. dothidea infection is regulated by a complicated mechanism. Targeting to MhAGO1, a negative regulator, miR168 plays a positive role in the resistance by alterations in diverse defense responses.

Identification of Micro Ribonucleic Acids and Their Targets in Response to Plasmodiophora brassicae Infection in Brassica napus

“…Similarly, bna-miR168b was upregulated in 409R (Figure 5B), which targets the AGO1 and Zinc finger transcription factor CCCH4. In Malus hupehensis, miR168 targets AGO1 and contributes to resistance against Botryosphaeria dothidea infection (Yu et al, 2017). Therefore, some of these identified DE miRNAs may regulate the target key transcripts/proteins through miRNA interference silencing complex (miRISC) to mediate host response to clubroot disease.…”

“…Therefore, the development of P. brassicae-resistant varieties is considered the most economical and effective approach to control the clubroot disease. To date, a number of clubroot resistant (CR) loci have been identified, such as CRa, CRb, CRc, CRk (Matsumoto et al, 1998;Piao et al, 2004;Sakamoto et al, 2008), Crr1, Crr2, Crr3, Crr4 (Suwabe et al, 2003(Suwabe et al, , 2006Hirai et al, 2004), CRd (Pang et al, 2018), PbBa3.1, PbBa3.2, PbBa3.3, PbBa1.1, PbBa8.1 (Chen et al, 2013, Rcr1 (Chu et al, 2014), Rcr4, Rcr8, and Rcr9 (Yu et al, 2017). Among these loci, CRa and Crr1 are isolated from Chinese cabbage and encode toll-interleukin-1 receptor/nucleotide-binding site/leucine-rich-repeat (TNL/TIR-NBS-LRR) proteins (Hatakeyama et al, 2013(Hatakeyama et al, , 2017.…”

A novel miRNA negatively regulates resistance to Glomerella leaf spot by suppressing expression of an NBS gene in apple

“…Some sRNAs facilitate plant resistance. M. hupehensis plants transiently overexpressing miR168 exhibited reduced sensitivity to Botryosphaeria dothidea infection 32 . Similarly, transgenic rice ( Oryza sativa ) plants overexpressing miR160a and miR398b displayed enhanced resistance to Magnaporthe oryzae , as demonstrated by decreased fungal growth, increased hydrogen peroxide accumulation at the infection site, and upregulated expression of defense-related genes 33 .…”

Small RNA and Degradome Sequencing Reveal Important MicroRNA Function in Nicotiana tabacum Response to Bemisia tabaci

“…Cotton plant could export mi166 to inhibit virulence gene expression in a fungal pathogen Verticillium dahlia [ 52 ]. In Malus hupehensis , miR168 targets to ARGONAUTE1 ( AGO1 ) and contributes to the defense against Botryosphaeria dothidea [ 53 ].…”