title: Multiple mutations in the T region of the Agrobacterium tumefaciens tumor-inducing plasmid.
abstract: Three genetic loci affecting tumor morphology lie within pTiA6NC T-DNA: tms, tmr, and tml. Using deletions and multiple transposon insertions, we constructed tumor-inducing (Ti) plasmids representing every possible double and triple mutant combination. tms tmr and tms tmr tml mutants did not incite tumors on most plants and produced a very weak response on a few other hosts but tms tml and tmr tml mutants were virulent. Thus, either tms+ or tmr+ alone can promote significant tumor growth but tml+ by itself is not sufficient. On hosts where tms mutants induce tumors accompanied by shoot proliferation, addition of a tml mutation reduces or eliminates shoot proliferation, suggesting that tml+ promotes shoot development. The small calli incited by tms tmr and tms tmr tml mutants contain agropine, an indication that these plant cells incorporate T-DNA in the absence of substantial tumor growth.
mesh_terms: D004251:DNA Transposable Elements; D009154:Mutation; D010937:Plant Growth Regulators / Q000502:physiology; D010941:Plant Tumors / Q000235:genetics*; D010957:Plasmids; D012231:Rhizobium / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D010937:Plant Growth Regulators