The Kinetics of T-strand Production in a Nopaline-Type Helper Strain of Agrobacterium tumefaciens. F. A. Culianez-Macia. Department of Agronomy, University of Illinois, 1102 S. Goodwin Avenue, Urbana 61801. A. G. Hepburn. Department of Agronomy, University of Illinois, 1102 S. Goodwin Avenue, Urbana 61801.. MPMI 1:207-214. Accepted 4 August 1988. Copyright 1988 The American Phytopathological Society.

The production of single-stranded DNA from the T-region in Agrobacterium tumefaciens is dependent on the induced cells being in an actively growing state. Once a culture approaches stationary phase, the cells of that culture are no longer inducible. After being induced, the cells continue producing single-stranded T-region derivatives from a nicked substrate well into the stationary phase of the culture, and the time of maximum T-strand production occurs approximately 24 hr after addition of the inducer. The data suggest that T-strand production will be greater in richer media where cell growth is greater. In the nopaline binary/helper combination used here, which contains a single left border from pTiT37 and vir region from pTiC58, maximum nicking of the border repeat occurs around 200–500 µM acetosyringone, but single-stranded DNA production from the nicked borders continues increasing to at least 1 mM acetosyringone. The data suggest that more than one single-stranded DNA molecule may be made from a given T-region under maximal induction conditions.