miR825 and miR825* function as negative regulators in Bacillus cereus AR156-elicited systemic resistance to Botrytis cinerea in Arabidopsis thaliana

Abstract

Background: Small RNAs function to regulate plant defense responses to pathogens. We previously showed that miR825 and miR825* downregulate Bacillus cereus AR156 (AR156)-triggered systemic resistance to Pseudomonas syringae pv. tomato DC3000 in Arabidopsis thaliana (Arabidopsis). The aim of this study was to unravel the role of miR825 and miR825* in AR156-mediated systemic resistance to Botrytis cinerea B1301 in Arabidopsis. Results: Northern blotting revealed that miR825 and miR825* were more strongly downregulated in wild type Arabidopsis Col-0 (Col-0) plants pretreated with AR156 than in non-treated plants upon B. cinerea B1301 infection. Furthermore, compared with Col-0, transgenic plants with attenuated miR825 and miR825* expression were more resistant to B. cinerea B1301, yet miR825- and miR825*-overexpressing (OE) plants were more prone to it. With AR156 pretreatment, the transcription of four defense-related genes (PR1, PR2, PR5, and PDF1.2) and cellular defense responses (hydrogen peroxide production and callose deposition) were faster and stronger in miR825 and miR825* knockdown lines, but weaker in their OE plants than in Col-0 plants upon pathogen attack. Also, AR156 pretreatment caused stronger phosphorylation of MPK3 and MPK6 and expression of FRK1 and WRKY53 genes upon B. cinerea B1301 inoculation in miR825 and miR825* knockdown plants than in Col-0 plants. Additionally, the assay of agrobacterium-mediated transient co-expression in Nicotiana benthamiana confirmed that AT5G40910, AT5G38850, AT3G04220, and AT5G44940 are target genes of miR825 or miR825*. Compared with Col-0, the target mutant lines showed higher susceptibility to B. cinerea B1301 while still expressing AR156-triggered ISR. The two-way ANOVA revealed a significant (P < 0.01) interactive effect of treatment and genotype on the defence responses. Conclusion: miR825 and miR825* act as negative regulators of AR156-mediated systemic resistance to B. cinerea B1301 in Arabidopsis. Our research have significant implications for effectively applying the two miRNAs to plant protection.

RcTGA1 and glucosinolate biosynthesis pathway involvement in the defence of rose against the necrotrophic fungus Botrytis cinerea

“…Liu et al found that BR signal transduction pathway-related genes were upregulated after infection with Botrytis c. , and exogenous BR enhanced its defence response to Botrytis c. , indicating that BR was involved in the resistance of rose to Botrytis c [ 12 ].. Exogenous 2,4-Epibrassinolide improves the resistance of grapes to Botrytis c. by inhibiting spore germination of Botrytis c. and enhancing the sensitization mechanism of grape fruit [ 13 , 14 ]. In addition, some microRNAs are also involved in plant defence against Botrytis c. Nie et al found that overexpressed miR825 and miR825 * improved the susceptibility of Arabidopsis to Botrytis c. In contrast, silencing miR825 and miR825 * enhanced the resistance of Arabidopsis to Botrytis c. , indicating that mir825 and mir825 * play a negative regulatory role in Arabidopsis defence against Botrytis c [ 15 ].…”

Downy Mildew effector HaRxL21 interacts with the transcriptional repressor TOPLESS to promote pathogen susceptibility

“…These include genes that impact resistance against biotrophic pathogens such as accelerated cell death 6 ( ACD6 ) and Cysteine-rich receptor-like kinase CRK13 [ 71 ] that positively regulate SA signalling [ 72 ], as well as Calmodulin-like CML41 that regulates flg22-induced stomatal closure [ 73 ]. Furthermore, miR825 target AT3G04220 [ 74 ] and the lipid transfer protein AZI3 [ 75 ] contribute to defence against necrotrophs and the lectin receptor kinase LecRK4.1 positively regulates Arabidopsis PTI and resistance against biotrophic and necrotrophic pathogens [ 76 ]. Reduction in expression of these genes is likely to contribute to the observed enhanced susceptibility of RxL21 over-expressing plants to both biotrophic and necrotrophic pathogens.…”

MiRNA and phasiRNAs-mediated regulation of TIR-NBS-LRR defense genes inArabidopsis thaliana

“…12 ). Interestingly, during preparation of this manuscript, a report established miR825-5p and 3p are involved in ISR triggered within the B. cereus / Botrytis cinerea pathosystem [76]. In regards to the transcriptional down regulation of MIR825 , a recent report showed that mutations that lead to over accumulation and nuclear localization of TNL protein SNC1 repress transcription of MIR genes, including MIR825 [54].…”