David M. Hunter,3
Ji-Shu Zhang,1 and
1College of Life Science, Northwest A&F University, Yangling, Shaanxi Province 712100, P. R. China; 2Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario N5V 4T3, Canada; 3Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, Vineland Station, Ontario L0R 2E0, Canada.
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Accepted 17 April 2013.
Agrobacterium tumefaciens has been widely used in plant genetic transformation. Hormone-encoding genes residing in the T-DNA region have been removed, resulting in disarmed Agrobacterium strains that are used in various transformation experiments. Nopaline Agrobacterium strains, however, carry another hormone gene, trans-zeatin synthesizing (tzs), that codes for trans-zeatin in the virulence region of the tumor-inducing plasmids. We investigated the activity and function of the tzs gene of a nopaline Agrobacterium sp. strain GV3101 in plant in vitro regeneration. Leaf explants of tobacco and Nicotiana benthamiana co-cultured with strain GV3101 exhibited active shoot regeneration in media without added plant growth regulators. On medium without plant growth regulators, transgenic shoots were also induced from explants co-cultured with GV3101 containing a binary vector. Enzyme-linked immunosorbent assay showed that cell-free extracts of Agrobacterium sp. strain GV3101 culture contained the trans-zeatin at 860 ng/liter. Polymerase chain reaction using tzs-specific primers showed that the tzs gene was present in strain GV3101 but not in other Agrobacterium strains. The study showed that the tzs gene in GV3101 was actively expressed, and that trans-zeatin produced in the Agrobacterium strain can promote plant shoot regeneration.
© 2013 The American Phytopathological Society