The Steps of Flower Development - Genes Are Implicated
Mendelian Genes Define the Committment to Flowering
Mendelian Genes Define Floral Organ Identity
Cloning Committment to Flowering and Flower Organ Genes
MADS-Box Genes
Analyzing Gene Expression with In Situ Hybridization
The Molecular Expression of Floral Committment Genes
MADS-Box Genes
The above table clearly demonstrates that MADS-box genes play a central role in the development of flowers in plants. The fact that snapdragon MADS-box genes were used as heterologous probes itself is evidence that this class of genes is important in other species. Further evidence of their importance has been demonstrated by the fact that homologous sequences have been found in monocots such as maize. So what are MADS-box genes?The cloning of AGAMOUS and DEFICIENS and the subsequent sequence analysis uncovered a similarity in structure to the transcriptional factor SRF of humans and yeast. (The term MADS is derived from the first letter of the genes MCM1, AGAMOUS, DEFICIENS, and SRF.) Each of these genes contains a 56-amino acid sequence that is necessary for the protein to bind to DNA. This sequence is located near the amino terminal end of the protein, and is called the MADS-box. Plant MADS-box genes contain a second conserved sequence called the K-domain because its sequences is similar to the coiled coil domain of keratin. This region has been implicated in the interaction of proteins. The following figure from Dr. Martin Yanofsky summarizes the general structure of MADS-box genes.
Copyright © 1998. Phillip McClean