Genes for seed storage proteins in legumes and cereals

The genes for seed storage proteins provide an excellent example of a cell and tissue specific expression. Using transgenic plants, sequences could be identified which were responsible for tissue or cell specific expression of these genes.

For instance, when wheat glutenin gene or barley hordein gene (each with its regulatory sequence) was fused to chloramphenicol acetyl transferase (CAT) gene and introduced into tobacco, CAT activity was found only in the endosperm.

Another reporter gene utilized for the same purpose is glucuronidase (GUS) gene, which also showed endosperm specific expression when fused with a wheat glutenin gene and its regulatory sequence. The regulatory sequence thus identified was called endosperm box of the storage protein genes.