Agrobacterium-produced and exogenous cytokinin-modulated Agrobacterium-mediated plant transformation

• Published in: Molecular plant pathology Vol. 11; no. 5; pp. 677 - 690
• Main Authors: HWANG, HAU-HSUAN, WANG, MING-HSUAN, LEE, YING-LING, TSAI, YUN-LONG, LI, YI-HO, YANG, FONG-JHIH, LIAO, YU-CHEN, LIN, SHAO-KAI, LAI, ERH-MIN
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.09.2010; Blackwell Publishing Ltd; Blackwell
• Subjects: Acetosyringone; Agrobacterium tumefaciens - drug effects; Agrobacterium tumefaciens - genetics; Agrobacterium tumefaciens - pathogenicity; Arabidopsis; Arabidopsis - drug effects; Arabidopsis - microbiology; Biological and medical sciences; Complementation; Crown gall; Cytokinins; Cytokinins - biosynthesis; Cytokinins - pharmacology; Data processing; DNA; DNA, Bacterial - genetics; Fundamental and applied biological sciences. Psychology; Genes, Bacterial - genetics; Genomes; Hormones; Infection; Integration; Mutation - genetics; Original; Phytopathology. Animal pests. Plant and forest protection; Plant Roots - drug effects; Plant Roots - microbiology; Plant Tubers - drug effects; Plant Tubers - microbiology; Plant Tumor-Inducing Plasmids - genetics; Plant Tumors - microbiology; Raphanus - drug effects; Raphanus - microbiology; Roots; Secretions; Species Specificity; Stems; T-DNA; Ti plasmid; Transformation; Transformation, Genetic - drug effects; Tumorigenesis; Virulence - drug effects; Zeatin - secretion; Exogenous; Agrobacterium; Modulation; Bacteria; Plant growth substance; Rhizobiaceae; Cytokinin; Gram negative bacteria
• ISSN: 1464-6722; 1364-3703
• DOI: 10.1111/j.1364-3703.2010.00637.x

Agrobacterium tumefaciens is a plant pathogenic bacterium that causes neoplastic growths, called 'crown gall', via the transfer and integration of transferred DNA (T-DNA) from the bacterium into the plant genome. We characterized an acetosyringone (AS)-induced tumour-inducing (Ti) plasmid gene, tzs (trans-zeatin synthesizing), that is responsible for the synthesis of the plant hormone cytokinin in nopaline-type A. tumefaciens strains. The loss of Tzs protein expression and trans-zeatin secretions by the tzs frameshift (tzs-fs) mutant is associated with reduced tumorigenesis efficiency on white radish stems and reduced transformation efficiencies on Arabidopsis roots. Complementation of the tzs-fs mutant with a wild-type tzs gene restored wild-type levels of trans-zeatin secretions and transformation efficiencies. Exogenous application of cytokinin during infection increased the transient transformation efficiency of Arabidopsis roots infected by strains lacking Tzs, which suggests that the lower transformation efficiency resulted from the lack of Agrobacterium-produced cytokinin. Interestingly, although the tzs-fs mutant displayed reduced tumorigenesis efficiency on several tested plants, the loss of Tzs enhanced tumorigenesis efficiencies on green pepper and cowpea. These data strongly suggest that Tzs, by synthesizing trans-zeatin at early stage(s) of the infection process, modulates plant transformation efficiency by A. tumefaciens.