Characterization of RCI-1, a chloroplastic rice lipoxygenase whose synthesis is induced by chemical plant resistance activators.
A full-length lipoxygenase cDNA (RCI-1) has been cloned from rice (Oryza sativa) whose corresponding transcripts accumulate in response to treatment of the plants with chemical inducers of acquired resistance such as benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH), 2,6-dichloroisonicotinic acid (INA), and probenazole. In contrast, RCI-1 transcript levels did not increase after inoculation with compatible and incompatible races of the rice blast fungus Magnaporthe grisea and the nonhost pathogen Pseudomonas syringae pv. syringae. RCI-1 transcript levels also increased after exogenous application of jasmonic acid, but not upon wounding. Dose-response and time course experiments revealed a similar pattern of transcript accumulation and lipoxygenase activity in BTH-treated rice leaves. Enzymatic analysis of recombinant RCI-1 protein produced in Escherichia coli revealed that 13-hydroperoxy-octadecanoic acids were the predominant reaction products when either linoleic or linolenic acid used as a substrate. The RCI-1 sequence features a putative chloroplast targeting sequence at its N-terminus. Indeed, a protein consisting of the putative chloroplast transit peptide fused to green fluorescent protein was exclusively localized in chloroplasts, indicating that RCI-1 is a chloroplastic enzyme.
Schaffrath
U
U
Institute of Biology III, RWTH Aachen, Germany; Institute of Plant Biology, University of Zurich, Switzerland.
Zabbai
F
F
Dudler
R
R
D000595:Amino Acid Sequence; D002736:Chloroplasts / Q000201:enzymology*; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004790:Enzyme Induction / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007113:Immunity, Innate; D007539:Isonicotinic Acids / Q000494:pharmacology*; D019787:Linoleic Acid / Q000378:metabolism; D008084:Lipoxygenase / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D020082:Magnaporthe / Q000502:physiology; D008969:Molecular Sequence Data; D012275:Oryza / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D011549:Pseudomonas / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013830:Thiadiazoles / Q000494:pharmacology*; D013844:Thiazoles / Q000494:pharmacology*; D014158:Transcription, Genetic; D017962:alpha-Linolenic Acid / Q000378:metabolism
D018076:DNA, Complementary; D018744:DNA, Plant; D007539:Isonicotinic Acids; D011993:Recombinant Fusion Proteins; D013830:Thiadiazoles; D013844:Thiazoles; D017962:alpha-Linolenic Acid; C099063:oryzemate; C077261:2,6-dichloroisonicotinic acid; D019787:Linoleic Acid; C099403:S-methyl benzo(1,2,3)thiadiazole-7-carbothioate; D008084:Lipoxygenase