title: Streptomyces turgidiscabies possesses a functional cytokinin biosynthetic pathway and produces leafy galls.
abstract: Streptomyces turgidiscabies, a cause of potato scab, possesses a mobilizable pathogenicity island containing multiple virulence genes and a cytokinin biosynthetic pathway. These biosynthetic genes are homologous and collinear with the fas operon in Rhodococcus fascians. Reverse-transcriptase polymerase chain reaction of S. turgidiscabies demonstrated that all six genes were transcribed in oat bran broth with and without glucose, though transcription was partially repressed by glucose. The supernatant of S. turgidiscabies cultures had cytokinin activity in callus initiation and differentiation assays. Arabidopsis and tobacco plants inoculated with a thaxtomin-deficient mutant (deltanos) produced leafy galls, indistinguishable from those produced by R. fascians. Deletion of the ipt gene in the pathway eliminated gall phenotype. Other symptoms on tobacco included production of hairy roots and de novo meristems.
authors.affiliation: Department of Plant Pathology, Cornell University, Ithaca, NY 14850, USA.
authors.forename: Madhumita V
authors.initials: MV
authors.lastname: Joshi
authors.forename: Rosemary
authors.initials: R
authors.lastname: Loria
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003583:Cytokinins / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D008954:Models, Biological; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology; D010941:Plant Tumors / Q000382:microbiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012240:Rhodococcus / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013302:Streptomyces / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D014026:Nicotiana / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D003583:Cytokinins