glyoxylate accumulation. Induction of transcription in infected plant In tobacco, infection of R. fascians leads to hyperexpression of a cytochrome P450, homologue to a gene involved in inactivation of abscisic acid in Arabidopsis thaliana, of a gibberellic acid oxidase, which inactivates this hormone and its precursors, a proline dehydrogenase, which has its transcription induced by cytokinin and turns proline into glutamic acid, and a factor involved in molybdenum cofactor, needed for sulfur, carbon and nitrogen metabolism control and for abscisic acid synthesis. Role of phytohormones during infection All the effects of R. fascians infection can be attributed to hormone hyperdosage. In particular, most of the effects are connected to auxin and cytokinin, such as: formation of green islands on leaves, wrinkling of laminae, bud proliferation, delay of senescence, and inhibition of lateral roots. In fact, R. fascians can produce itself cytokinin, or cytokinin-like compounds: using orf4 and orf5 in the fas operon, it can stimulate infected plants to produce cytokinin, and it can produce indole-3-acetic acid itself, using a pathway starting from tryptophan and passing through production of 3-indol-piruvic acid and 3-indol-acetaldeid. R.fascians can also degrade cytokinin to influence the cytokinin/auxin ratio. Beside cytokinin and auxin, R. fascians acts on other hormones: in particular, it can block abscisic acid and gibberellic acid synthesis in infected plants. Abscisic acid represses growth, so a block of production is needed to allow proliferation of cells in leafy galls. Gibberellic acid controls cellular differentiation, so its block is needed for maintenance of meristematic cells and for their proliferation. Plant diseases R. fascians causes diseases in several host plants including tobacco, small fruits (caneberries, strawberries) and ornamental plants (butterfly flowers, Primula, kalanchoes, Impatiens, geraniums, carnations) References External links Type strain of Rhodococcus fascians at BacDive - the Bacterial Diversity Metadatabase Mycobacteriales Bacterial plant pathogens and diseases Tobacco diseases Small fruit diseases Bacterial strawberry diseases Ornamental plant pathogens and diseases