orf13 T-DNA gene of Agrobacterium rhizogenes confers meristematic competence to differentiated cells

• Published in: Plant physiology (Bethesda) Vol. 135; no. 3; pp. 1798 - 1808
• Main Authors: Stieger, P.A, Meyer, A.D, Kathmann, P, Frundt, C, Niederhauser, I, Barone, M, Kuhlemeier, C
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.07.2004; American Society of Plant Physiologists; Oxford University Press ; American Society of Plant Biologists
• Subjects: Agrobacterium rhizogenes; Agronomy. Soil science and plant productions; Auxins; bacterial proteins; Base Sequence; Biological and medical sciences; Cell cycle; Cell Differentiation; Cytokinins; DNA Primers; DNA, Bacterial; DNA, Bacterial - genetics; DNA, Complementary; DNA, Complementary - genetics; DNA, Plant; DNA, Plant - genetics; DNA, Single-Stranded; DNA, Single-Stranded - genetics; Fundamental and applied biological sciences. Psychology; Genetic engineering applications; Genetics and breeding of economic plants; homeodomain proteins; Homeostasis; knotted1-like protein; Leaves; Life Sciences; Lycopersicon esculentum; Lycopersicon esculentum - cytology; Lycopersicon esculentum - genetics; Lycopersicon esculentum - growth & development; Lycopersicon esculentum - microbiology; Meristem; Meristem - cytology; Meristem - physiology; Meristems; Molecular Sequence Data; nucleotide sequences; Open Reading Frames; phenotypic variation; Plant breeding: fundamental aspects and methodology; Plant cells; Plant Diseases; Plant Diseases - microbiology; Plant growth; Plant Growth Regulators; Plant Growth Regulators - physiology; Plant interaction; plant morphology; plant pathogenic bacteria; Plant roots; Plants; Polymerase Chain Reaction; Rhizobium; Rhizobium - genetics; Rhizobium rhizogenes; signal transduction; Signal Transduction and Hormone Action; Solanum lycopersicum var. lycopersicum; tomatoes; transcription factors; transfer DNA; transgenic plants; Vegetal Biology; Zea mays; Monocotyledones; Zea mays; Gene expression; Regulation(control); Gramineae; Dicotyledones; Angiospermae; Cell cycle; Lycopersicon esculentum; Bacteria; Spermatophyta; Transgenic plant; Rhizobiaceae; Solanaceae; Agrobacterium rhizogenes; Transcription factor
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.104.040899

Plant infections by the soil bacterium Agrobacterium rhizogenes result in neoplastic disease with the formation of hairy roots at the site of infection. Expression of a set of oncogenes residing on the stably integrated T-DNA is responsible for the disease symptoms. Besides the rol (root locus) genes, which are essential for the formation of hairy roots, the open reading frame orf13 mediates cytokinin-like effects, suggesting an interaction with hormone signaling pathways. Here we show that ORF13 induced ectopic expression of KNOX (KNOTTED1-like homeobox) class transcription factors, as well as of several genes involved in cell cycle control in tomato (Lycopersicon esculentum). ORF13 has a retinoblastoma (RB)-binding motif and interacted with maize (Zea mays) RB in vitro, whereas ORF13, bearing a point mutation in the RB-binding motif (ORF13*), did not. Increased cell divisions in the vegetative shoot apical meristem and accelerated formation of leaf primordia were observed in plants expressing orf13, whereas the expression of orf13* had no influence on cell division rates in the shoot apical meristem, suggesting a role of RB in the regulation of the cell cycle in meristematic tissues. On the other hand, ectopic expression of LeT6 was not dependent on a functional RB-binding motif. Hormone homeostasis was only altered in explants of leaves, whereas in the root no effects were observed. We suggest that ORF13 confers meristematic competence to cells infected by A. rhizogenes by inducing the expression of KNOX genes and promotes the transition of infected cells from the G1 to the S phase by binding to RB.