title: OsbHLH148, a basic helix-loop-helix protein, interacts with OsJAZ proteins in a jasmonate signaling pathway leading to drought tolerance in rice.
abstract: Jasmonates play important roles in development, stress responses and defense in plants. Here, we report the results of a study using a functional genomics approach that identified a rice basic helix-loop-helix domain gene, OsbHLH148, that conferred drought tolerance as a component of the jasmonate signaling module in rice. OsbHLH148 transcript levels were rapidly increased by treatment with methyl jasmonate (MeJA) or abscisic acid, and abiotic stresses including dehydration, high salinity, low temperature and wounding. Transgenic over-expression of OsbHLH148 in rice confers plant tolerance to drought stress. Expression profiling followed by DNA microarray and RNA gel-blot analyses of transgenic versus wild-type rice identified genes that are up-regulated by OsbHLH148 over-expression. These include OsDREB and OsJAZ genes that are involved in stress responses and the jasmonate signaling pathway, respectively. OsJAZ1, a rice ZIM domain protein, interacted with OsbHLH148 in yeast two-hybrid and pull-down assays, but it interacted with the putative OsCOI1 only in the presence of coronatine. Furthermore, the OsJAZ1 protein was degraded by rice and Arabidopsis extracts in the presence of coronatine, and its degradation was inhibited by MG132, a 26S proteasome inhibitor, suggesting 26S proteasome-mediated degradation of OsJAZ1 via the SCF(OsCOI1) complex. The transcription level of OsJAZ1 increased upon exposure of rice to MeJA. These results show that OsJAZ1 could act as a transcriptional regulator of the OsbHLH148-related jasmonate signaling pathway leading to drought tolerance. Thus, our study suggests that OsbHLH148 acts on an initial response of jasmonate-regulated gene expression toward drought tolerance, constituting the OsbHLH148-OsJAZ-OsCOI1 signaling module in rice.
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea.
authors.forename: Ju-Seok
authors.initials: JS
authors.lastname: Seo
authors.forename: Joungsu
authors.initials: J
authors.lastname: Joo
authors.forename: Min-Jeong
authors.initials: MJ
authors.lastname: Kim
authors.forename: Yeon-Ki
authors.initials: YK
authors.lastname: Kim
authors.forename: Baek Hie
authors.initials: BH
authors.lastname: Nahm
authors.forename: Sang Ik
authors.initials: SI
authors.lastname: Song
authors.forename: Jong-Joo
authors.initials: JJ
authors.lastname: Cheong
authors.forename: Jong Seob
authors.initials: JS
authors.lastname: Lee
authors.forename: Ju-Kon
authors.initials: JK
authors.lastname: Kim
authors.forename: Yang Do
authors.initials: YD
authors.lastname: Choi
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism*; D018744:DNA, Plant / Q000235:genetics; D055864:Droughts; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008954:Models, Biological; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D012275:Oryza / Q000235:genetics* / Q000378:metabolism*; D054883:Oxylipins / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013312:Stress, Physiological; D015854:Up-Regulation
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D003517:Cyclopentanes; D018744:DNA, Plant; D054883:Oxylipins; D010940:Plant Proteins; C011006:jasmonic acid