Gene expression in plants

Confocal micrograph showing the expression of different fluorescent proteins in the stem of a thale cress seedling (Arabidopsis thaliana) used to study in vivo gene expression. These genetically modified plants have fluorescent proteins associated with different gene promoters. Promoters are sequences of DNA that act as 'genetic switches' turning on the expression of particular genes. In these plants, when a promoter switches a gene on, a corresponding fluorescent protein is produced, allowing expression of these genes to be viewed. In this image green fluorescence (GFP) shows the expression of one gene and the red fluorescence corresponds to the expression of a different gene. Cells that are yellow express both genes. A third fluorescent protein is attached to the plasma membrane to show the outline of each cell in blue.