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Yu X, Hu K, Geng X, Cao L, Zhou T, Lin X, Liu H, Chen J, Luo C, Qu S. The Mh-miR393a-TIR1 module regulates Alternaria alternata resistance of Malus hupehensis mainly by modulating the auxin signaling. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2024; 341:112008. [PMID: 38307352 DOI: 10.1016/j.plantsci.2024.112008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 01/12/2024] [Accepted: 01/29/2024] [Indexed: 02/04/2024]
Abstract
miRNAs govern gene expression and regulate plant defense. Alternaria alternata is a destructive fungal pathogen that damages apple. The wild apple germplasm Malus hupehensis is highly resistant to leaf spot disease caused by this fungus. Herein, we elucidated the regulatory and functional role of miR393a in apple resistance against A. alternata by targeting Transport Inhibitor Response 1. Mature miR393 accumulation in infected M. hupehensis increased owing to the transcriptional activation of MIR393a, determined to be a positive regulator of A. alternata resistance to either 'Orin' calli or 'Gala' leaves. 5' RLM-RACE and co-transformation assays showed that the target of miR393a was MhTIR1, a gene encoding a putative F-box auxin receptor that compromised apple immunity. RNA-seq analysis of transgenic calli revealed that MhTIR1 upregulated auxin signaling gene transcript levels and influenced phytohormone pathways and plant-pathogen interactions. miR393a compromised the sensitivity of several auxin-signaling genes to A. alternata infection, whereas MhTIR1 had the opposite effect. Using exogenous indole-3-acetic acid or the auxin synthesis inhibitor L-AOPP, we clarified that auxin enhances apple susceptibility to this pathogen. miR393a promotes SA biosynthesis and impedes pathogen-triggered ROS bursts by repressing TIR1-mediated auxin signaling. We uncovered the mechanism underlying the miR393a-TIR1 module, which interferes with apple defense against A. alternata by modulating the auxin signaling pathway.
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Affiliation(s)
- Xinyi Yu
- College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Kaixu Hu
- College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Xiaoyue Geng
- College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China; Xuzhou Institute of Agricultural Sciences in Jiangsu Xuhuai District, Xuzhou, Jiangsu 221131, PR China
| | - Lifang Cao
- College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Tingting Zhou
- College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Xinxin Lin
- College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Hongcheng Liu
- College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Jingrui Chen
- College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Changguo Luo
- Institute of Fruit Science, Guizhou Academy of Agricultural Science, Guiyang, Guizhou 550006, PR China.
| | - Shenchun Qu
- College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
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