Cytokinin/auxin balance in crown gall tumors is regulated by specific loci in the T-DNA

We describe here the application of some new analytical techniques to the measurement of hormone levels in tumors that have altered morphologies as a result of Tn5 insertion in

D. E. Akiyoshi; R. O. Morris; R. Hinz; B. S. Mischke; T. Kosuge; D. J. Garfinkel; M. P. Gordon; E. W. Nester

2006

Scholarcy highlights

  • Insertion ofthe transposon Tn5 into the T-region ofthe octopine Ti plasmid ofAgrobacterium tumefiaciens gives rise to crown gall tumors having altered morphology
  • It is known from the work ofseveral laboratories that a segment of DNA, the transferred region of a large plasmid harbored by the inciting bacterium, Agrobacterium tumefaciens, is integrated into the host genome during crown gall tumorigenesis
  • A tumor on tobacco induced by the parental strain A348 is characterized 5 wk after inoculation by an unorganized morphology and a weight of up to 10 g
  • Amasino and Miller noted similar correlations between phytohormone content and the morphology of tumors incited by natural isolates of A. tumefaciens
  • Tumors incited by tmr mutants formed roots and had trans-ribosylzeatin/indoleacetic acid ratios of about 0.005
  • Insertional inactivation of the tmr locus dramatically reduces the trans-ribosylzeatin content oftumor tissue, suggesting that this locus plays a central role in cytokinin metabolism in the tumor
  • The results ofa more extensive survey showed that there was no statistically significant difference between the cytokinin levels of tin and parental tumors

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