 Some genes are only expressed in certain tissue, so reporter genes, like GUS, can be attached to the gene of interest allowing visualization of the location.Other ways to test a gene is to alter it slightly and then return it to the plant and see if it still has the same effect on phenotype.Other strategies include attaching the gene to a strong promoter and see what happens when it is over expressed, forcing a gene to be expressed in a different location or at different developmental stages.