title: Involvement of EARLY BUD-BREAK, an AP2/ERF Transcription Factor Gene, in Bud Break in Japanese Pear (Pyrus pyrifolia Nakai) Lateral Flower Buds: Expression, Histone Modifications and Possible Target Genes.
abstract: In the Japanese pear (Pyrus pyrifolia Nakai) 'Kosui', three developmental stages of lateral flower buds have been proposed to occur during ecodormancy to the flowering phase, i.e. rapid enlargement, sprouting and flowering. Here, we report an APETALA2/ethylene-responsive factor (AP2/ERF) transcription factor gene, named pear EARLY BUD-BREAK (PpEBB), which was highly expressed during the rapid enlargement stage occurring prior to the onset of bud break in flower buds. Gene expression analysis revealed that PpEBB expression was dramatically increased during the rapid enlargement stage in three successive growing seasons. PpEBB transcript levels peaked 1 week prior to onset of bud break in 'Kosui' potted plants treated with hydrogen cyanamide or water under forcing conditions. Chromatin immunoprecipitation-quantitative PCR showed that higher levels of active histone modifications (trimethylation of the histone H3 tail at Lys4) in the 5'-upstream and start codon regions of the PpEBB gene were associated with the induced expression level of PpEBB during the rapid enlargement stage. In addition, we provide evidence that PpEBB may interact with and regulate pear four D-type cyclin (PpCYCD3) genes during bud break in 'Kosui' lateral flower buds. PpEBB significantly increased the promoter activities of four PpCYCD3 genes in a dual-luciferase assay using tobacco leaves. Taken together, our findings uncovered aspects of the bud break regulatory mechanism in the Japanese pear and provided further evidence that the EBB family plays an important role in bud break in perennial plants.
authors.affiliation: NARO Institute of Fruit Tree Science, Tsukuba, Ibaraki, 305-8605 Japan.
authors.forename: Pham
authors.initials: P
authors.lastname: Anh Tuan
authors.affiliation: NARO Institute of Fruit Tree Science, Tsukuba, Ibaraki, 305-8605 Japan Present address: Institute of Fruit Science, College of Agriculture & Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China.
authors.forename: Songling
authors.initials: S
authors.lastname: Bai
authors.affiliation: NARO Institute of Fruit Tree Science, Tsukuba, Ibaraki, 305-8605 Japan Present address: Graduate School of Horticulture, Chiba University, Matsudo, Chiba, 271-8510 Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Saito
authors.affiliation: NARO Institute of Fruit Tree Science, Tsukuba, Ibaraki, 305-8605 Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Imai
authors.affiliation: NARO Institute of Fruit Tree Science, Tsukuba, Ibaraki, 305-8605 Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Ito
authors.affiliation: NARO Institute of Fruit Tree Science, Tsukuba, Ibaraki, 305-8605 Japan takaya@affrc.go.jp.
authors.forename: Takaya
authors.initials: T
authors.lastname: Moriguchi
mesh_terms: D056741:Cyclin D / Q000235:genetics / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D042421:Histone Code / Q000235:genetics*; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D031989:Pyrus / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D056741:Cyclin D; D005030:Ethylenes; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014157:Transcription Factors; C036216:ethylene
keywords: AP2/ERF transcription factor; Bud break; Cyclin D; Histone modification; Hydrogen cyanamide; Japanese pear (Pyrus pyrifolia Nakai)