Arabidopsis thaliana plants differentially modulate auxin biosynthesis and transport during defense responses to the necrotrophic pathogen Alternaria brassicicola

• Published in: The New phytologist 2012-09, Vol.195 (4), p.872-882
• Main Authors: Qi, Linlin, Yan, Jiao, Li, Yanan, Jiang, Hongling, Sun, Jiaqiang, Chen, Qian, Li, Haoxuan, Chu, Jinfang, Yan, Cunyu, Sun, Xiaohong, Yu, Yuanjie, Li, Changbao, Li, Chuanyou
• Format: Article
• Language: English
• Subjects: Alternaria; Alternaria - drug effects; Alternaria - physiology; Alternaria brassicicola; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - immunology; Arabidopsis - microbiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; auxin; Auxins; Biological Transport - drug effects; Biosynthesis; Cyclopentanes - pharmacology; Defence mechanisms; Defense mechanisms; Down-Regulation - drug effects; Flowers & plants; Gene expression; Gene expression regulation; Gene Expression Regulation, Plant - drug effects; Genes; Genes, Plant - genetics; genetic markers; Hevein; Host plants; Host-Pathogen Interactions - drug effects; Host-Pathogen Interactions - genetics; indole acetic acid; Indoleacetic Acids - metabolism; Infections; jasmonate; mutants; Mutation - genetics; necrotrophic pathogen; Oxylipins - pharmacology; Pathogenesis; Pathogens; Plant Diseases - microbiology; Plant immunity; Plant resistance; Plants; Seedlings; Signaling; Transport
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2012.04208.x

• Although the role of auxin in biotrophic pathogenesis has been extensively studied, relatively little is known about its role in plant resistance to necrotrophs. • Arabidopsis thaliana mutants defective in different aspects of the auxin pathway are generally more susceptible than wild‐type plants to the necrotrophic pathogen Alternaria brassicicola. We show that A. brassicicola infection up‐regulates auxin biosynthesis and down‐regulates the auxin transport capacities of infected plants, these effects being partially dependent on JA signaling. We also show that these effects of A. brassicicola infection together lead to an enhanced auxin response in host plants. • Application of IAA and MeJA together synergistically induces the expression of defense marker genes PDF1.2 (PLANT DEFENSIN 1.2) and HEL (HEVEIN‐LIKE), suggesting that enhancement of JA‐dependent defense signaling may be part of the auxin‐mediated defense mechanism involved in resistance to necrotrophic pathogens. • Our results provide molecular evidence supporting the hypothesis that JA and auxin interact positively in regulating plant resistance to necrotrophic pathogens and that activation of auxin signaling by JA may contribute to plant resistance to necrotrophic pathogens.