Wild type and transgenic tobacco plants expressing isopentenyltransferase, a gene coding the ratelimiting
step in cytokinin synthesis, were grown under limited nitrogen (N) conditions. Our results
indicated that the WT plants subjected to N deficiency displayed reduced biomass and relative growth
rates, increased levels of oxidative damage and reduced foliar concentrations of the different N forms.
However, the transgenic plants expressing PSARK::IPT, in spite of showing a significant decline in all the
N forms in the leaf, avoided the alteration of the oxidative metabolism and maintained biomass and
the relative growth rates at control levels, under suboptimal N conditions. These results suggest that
the increased cytokinin synthesis in the transgenic plants is an effective mechanism to improve N-use
efficiency.