Every plant cell typically has one or two copies of the entire collection of genes, termed the genome, in its DNA. Although all genes are present in a cell, which genes are active or switched on may vary. A gene may be on in some cells of a tissue and off in others, giving each gene a pattern of expression. We can see these patterns of expression by marking the proteins produced by specific genes with fluorescent proteins, as shown in these images of Arabidopsis buds (meristems), taken by Nathanael Prunet.
Images courtesy of Nathanael Prunet.
These patterns of gene expression are established in growing buds through gene interactions. When genes expressed in different regions influence cell properties and growth, they may create conflicts that lead to changes in shape, much as colouring in different regions of plastic, or sticking tape to one side of paper can lead to shape changes. It is through patterned gene activity introducing three types of conflict that plants are able to shape themselves.