The LeATL6-associated ubiquitin/proteasome system may contribute to fungal elicitor-activated defense response via the jasmonic acid-dependent signaling pathway in tomato.
The expression of LeATL6, an ortholog of Arabidopsis ATL6 that encodes a RING-H2 finger protein, was induced in tomato roots treated with a cell wall protein fraction (CWP) elicitor of the biocontrol agent Pythium oligandrum. The LeATL6 protein was expressed as a fusion protein with a maltose-binding protein (MBP) in Escherichia coli, and it catalyzed the transfer of ubiquitin to the MBP moiety on incubation with ubiquitin, the ubiquitin-activating enzyme E1, and the ubiquitin-conjugating enzyme E2; this indicated that LeATL6 represents ubiquitin ligase E3. LeATL6 expression also was induced by elicitor treatment of jail-1 mutant tomato cells in which the jasmonic acid (JA)-mediated signaling pathway was impaired; however, JA-dependent expression of the basic PR-6 and TPI-1 genes that encode proteinase inhibitor II and I, respectively, was not induced in elicitor-treated jail-1 mutants. Furthermore, transient overexpression of LeATL6 under the control of the Cauliflower mosaic virus 35S promoter induced the basic PR6 and TPI-1 expression in wild tomato but not in the jail-1 mutant. In contrast, LeATL6 overexpression did not activate salicylic acid-responsive acidic PR-1 and PR-2 promoters in wild tomato. These results indicated that elicitor-responsive LeATL6 probably regulates JA-dependent basic PR6 and TPI-1 gene expression in tomato. The LeATL6-associated ubiquitin/proteasome system may contribute to elicitor-activated defense responses via a JA-dependent signaling pathway in plants.
Hondo
Daisuke
D
Department of Life Science, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
Hase
Shu
S
Kanayama
Yoshinori
Y
Yoshikawa
Nobuyuki
N
Takenaka
Shigehito
S
Takahashi
Hideki
H
D000595:Amino Acid Sequence; D003517:Cyclopentanes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007113:Immunity, Innate / Q000235:genetics; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D008969:Molecular Sequence Data; D009154:Mutation; D054883:Oxylipins; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D030821:Plants, Genetically Modified; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011775:Pythium / Q000254:growth & development; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D025801:Ubiquitin / Q000378:metabolism*
C519621:ATL6 protein, Lycopersicon esculentum; D003517:Cyclopentanes; D054883:Oxylipins; D010940:Plant Proteins; D025801:Ubiquitin; D049452:Green Fluorescent Proteins; C011006:jasmonic acid; D046988:Proteasome Endopeptidase Complex