Secretome Analysis Reveals an Arabidopsis Lipase Involved in Defense against Alternaria brassicicola

• Published in: The Plant cell 2005-10, Vol.17 (10), p.2832-2847
• Main Authors: Oh, Il Seok, Park, Ae Ran, Bae, Min Seok, Kwon, Sun Jae, Kim, Young Soon, Lee, Ji Eun, Kang, Na Young, Lee, Sumin, Cheong, Hyeonsook, Park, Ohkmae K
• Format: Article
• Language: English
• Subjects: Alternaria - physiology; Alternaria brassicicola; Amino Acid Motifs - genetics; amino acid sequences; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis Proteins - genetics; Arabidopsis Proteins - isolation & purification; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Carboxylic Ester Hydrolases - genetics; Carboxylic Ester Hydrolases - isolation & purification; Carboxylic Ester Hydrolases - metabolism; Cell walls; Cells, Cultured; Conserved Sequence - genetics; Cultured cells; Disease resistance; ethephon; fungal diseases of plants; Fungal spores; Gels; gene expression regulation; Gene Expression Regulation, Plant - genetics; genes; Genetic Predisposition to Disease - genetics; GLIP1 gene; host-pathogen relationships; Immunity, Innate - genetics; Inoculation; Leaves; Lipase - genetics; Lipase - isolation & purification; Lipase - metabolism; messenger RNA; Molecular Sequence Data; Mutation - genetics; nucleotide sequences; Organophosphorus Compounds - pharmacology; Plant cells; Plant diseases; Plant Diseases - genetics; plant pathogenic fungi; Plant resistance; Plants; protein secretion; Proteins; Proteomics; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Recombinant Fusion Proteins - pharmacology; Salicylic Acid - pharmacology; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid; transcription (genetics); Transcriptional Activation - drug effects; Transcriptional Activation - genetics; triacylglycerol lipase
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.105.034819

The Arabidopsis thaliana secretome was analyzed by the proteomic approach, which led to the identification of secreted proteins implicated in many aspects of cell biology. We then investigated the change in the Arabidopsis secretome in response to salicylic acid and identified several proteins involved in pathogen response. One of these, a secreted lipase with a GDSL-like motif designated GDSL LIPASE1 (GLIP1), was further characterized for its function in disease resistance. glip1 plants were markedly more susceptible to infection by the necrotrophic fungus Alternaria brassicicola compared with the parental wild-type plants. The recombinant GLIP1 protein possessed lipase and antimicrobial activities that directly disrupt fungal spore integrity. Furthermore, GLIP1 appeared to trigger systemic resistance signaling in plants when challenged with A. brassicicola, because pretreatment of the glip1 mutant with recombinant GLIP1 protein inhibited A. brassicicola-induced cell death in both peripheral and distal leaves. Moreover, glip1 showed altered expression of defense- and ethylene-related genes. GLIP1 transcription was increased by ethephon, the ethylene releaser, but not by salicylic acid or jasmonic acid. These results suggest that GLIP1, in association with ethylene signaling, may be a critical component in plant resistance to A. brassicicola.