Recombinant DNA constructs, for use in plants and plant cells, have site-specific recombination sites that allow assessing phenotypes and modes of action by over expression or suppression of endogenous genes. In an aspect, a single DNA construct can be switched between over expression and suppression by the action of a recombinase such as the Cre recombinase on constructs having lox recombination sites. Other useful recombination systems include the Flp/frt system, the R/Rs system, the Dre/rox system, and the GIN/gix system.
