title: Peach [Prunus persica (L.) Batsch] KNOPE1, a class 1 KNOX orthologue to Arabidopsis BREVIPEDICELLUS/KNAT1, is misexpressed during hyperplasia of leaf curl disease.
abstract: Class 1 KNOTTED-like (KNOX) transcription factors control cell meristematic identity. An investigation was carried out to determine whether they maintain this function in peach plants and might act in leaf curliness caused by the ascomycete Taphrina deformans. KNOPE1 function was assessed by overexpression in Arabidopsis and by yeast two-hybrid assays with Arabidopsis BELL proteins. Subsequently, KNOPE1 mRNA and zeatin localization was monitored during leaf curl disease. KNOPE1 and Arabidopsis BREVIPEDICELLUS (BP) proteins fell into the same phyletic group and recognized the same BELL factors. 35S:KNOPE1 Arabidopsis lines exhibited altered traits resembling those of BP-overexpressing lines. In peach shoot apical meristem, KNOPE1 was expressed in the peripheral and central zones but not in leaf primordia, identically to the BP expression pattern. These results strongly suggest that KNOPE1 must be down-regulated for leaf initiation and that it can control cell meristem identity equally as well as all class 1 KNOX genes. Leaves attacked by T. deformans share histological alterations with class 1 KNOX-overexpressing leaves, including cell proliferation and loss of cell differentiation. Both KNOPE1 and a cytokinin synthesis ISOPENTENYLTRANSFERASE gene were found to be up-regulated in infected curled leaves. At early disease stages, KNOPE1 was uniquely triggered in the palisade cells interacting with subepidermal mycelium, while zeatin vascular localization was unaltered compared with healthy leaves. Subsequently, when mycelium colonization and asci development occurred, both KNOPE1 and zeatin signals were scattered in sectors of cell disorders. These results suggest that KNOPE1 misexpression and de novo zeatin synthesis of host origin might participate in hyperplasia of leaf curl disease.
authors.affiliation: Institute of Biology and Agricultural Biotechnology, National Research Council of Italy (CNR), via Salaria km 29,300, 00015 Monterotondo Scalo, Rome, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Testone
authors.forename: Leonardo
authors.initials: L
authors.lastname: Bruno
authors.forename: Emiliano
authors.initials: E
authors.lastname: Condello
authors.forename: Adriana
authors.initials: A
authors.lastname: Chiappetta
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bruno
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mele
authors.forename: Andrea
authors.initials: A
authors.lastname: Tartarini
authors.forename: Laura
authors.initials: L
authors.lastname: Spanò
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Innocenti
authors.forename: Domenico
authors.initials: D
authors.lastname: Mariotti
authors.forename: Maria Beatrice
authors.initials: MB
authors.lastname: Bitonti
authors.forename: Donato
authors.initials: D
authors.lastname: Giannino
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D003583:Cytokinins / Q000494:pharmacology; D015536:Down-Regulation; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010935:Plant Diseases; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D027861:Prunus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D015026:Zeatin / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D003583:Cytokinins; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D015026:Zeatin