Complementation of Agrobacterium tumefaciens tumor-inducing aux mutants by genes from the T(R)-region of the Ri plasmid of Agrobacterium rhizogenes.

Abstract

In this paper we provide information indicating that the agropine-type root-inducing (Ri) plasmid pRi1855 of Agrobacterium rhizogenes contains functional genes for auxin production (aux) in the right transferred DNA (T-DNA) region (T(R)-region). These genes were cloned and introduced into the T-region of the tumor-inducing (Ti) plasmids of mutants of Agrobacterium tumefaciens carrying an aux mutation. Depending on the Ri aux gene present, the oncogenicity of the Ti aux-1 and/or aux-2 mutations was restored, showing that the Ri aux genes are able to complement the Ti aux genes. Agrobacterium strains with an agropine-type Ri plasmid not only cause hairy root on certain plant species, but they also induce tumors on other plant species. In this paper it is shown that a mutation in either of the aux genes in the Ri plasmid leads to a total loss of tumorigenicity and a strongly diminished rhizogenicity of the host bacterium, revealing that the aux genes are important for tumor and root induction. Agrobacterium strains containing the T(R)-region but not the T(L) (left)-region of the Ri plasmid are still tumorigenic on certain plant species but are no longer capable of hairy-root induction.

• Authors: I A Offringa, L S Melchers, A J Regensburg-Tuink, P Costantino, R A Schilperoort, P J Hooykaas
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 83 Issue 18 Pg. 6935-9 (Sep 1986) ISSN: 0027-8424 [Print] United States
• PMID: 16593762 (Publication Type: Journal Article)