Arabidopsis ABCG34 contributes to defense against necrotrophic pathogens by mediating the secretion of camalexin.

Abstract

Plant pathogens cause huge yield losses. Plant defense often depends on toxic secondary metabolites that inhibit pathogen growth. Because most secondary metabolites are also toxic to the plant, specific transporters are needed to deliver them to the pathogens. To identify the transporters that function in plant defense, we screened Arabidopsis thaliana mutants of full-size ABCG transporters for hypersensitivity to sclareol, an antifungal compound. We found that atabcg34 mutants were hypersensitive to sclareol and to the necrotrophic fungi Alternaria brassicicola and Botrytis cinereaAtABCG34 expression was induced by Abrassicicola inoculation as well as by methyl-jasmonate, a defense-related phytohormone, and AtABCG34 was polarly localized at the external face of the plasma membrane of epidermal cells of leaves and roots. atabcg34 mutants secreted less camalexin, a major phytoalexin in Athaliana, whereas plants overexpressing AtABCG34 secreted more camalexin to the leaf surface and were more resistant to the pathogen. When treated with exogenous camalexin, atabcg34 mutants exhibited hypersensitivity, whereas BY2 cells expressing AtABCG34 exhibited improved resistance. Analyses of natural Arabidopsis accessions revealed that AtABCG34 contributes to the disease resistance in naturally occurring genetic variants, albeit to a small extent. Together, our data suggest that AtABCG34 mediates camalexin secretion to the leaf surface and thereby prevents Abrassicicola infection.

• Authors: Deepa Khare, Hyunju Choi, Sung Un Huh, Barbara Bassin, Jeongsik Kim, Enrico Martinoia, Kee Hoon Sohn, Kyung-Hee Paek, Youngsook Lee
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 114 Issue 28 Pg. E5712-E5720 (07 11 2017) ISSN: 1091-6490 [Electronic] United States
• PMID: 28652324 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ABCG34 protein, Arabidopsis
• ATP Binding Cassette Transporter, Subfamily G
• Acetates
• Arabidopsis Proteins
• Cyclopentanes
• Diterpenes
• Indoles
• Oxylipins
• Thiazoles
• camalexin
• Green Fluorescent Proteins
• methyl jasmonate
• sclareol

Topics

• ATP Binding Cassette Transporter, Subfamily G (metabolism)
• Acetates (pharmacology)
• Alternaria (pathogenicity)
• Arabidopsis (metabolism, microbiology)
• Arabidopsis Proteins (metabolism)
• Biological Transport
• Botrytis (metabolism)
• Cyclopentanes (pharmacology)
• Diterpenes (pharmacology)
• Gene Expression Profiling
• Gene Expression Regulation, Plant
• Green Fluorescent Proteins (metabolism)
• Indoles (metabolism)
• Mutation
• Oxylipins (pharmacology)
• Phenotype
• Phylogeny
• Plant Diseases (microbiology)
• Plant Leaves (metabolism)
• Signal Transduction
• Thiazoles (metabolism)