CHARACTERIZATION AND EXPRESSION OF A PUTATIVE RETINOBLASTOMA PROTEIN BINDING GENE FROM GOSSYPIUM HIRSUTUM

Authors: Taliercio, Earl; Ray, Jeffery - Jeff

Submitted to: DNA Sequence
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2006
Publication Date: 8/1/2006
Citation: Taliercio, E.W., Ray, J.D. 2006. Characterization and expression of a putative retinoblastoma protein binding gene from gossypium hirsutum. DNA Sequence. Vol 17: 307-310

Interpretive Summary: Cotton fibers are unique cell types that grow very long but never divide. The fact that fibers never divide is one factor that makes cotton fibers good for making cloth. Previous work has shown that as the fibers age about 20% replicate their DNA in preparation for cell division. This variation in DNA content may be reflected in a lack of uniformity in fiber cells and reduce the utility of these fibers in making cloth. A gene important in controlling cell division in other plants is investigated in cotton fiber. This gene is called a retinoblastoma binding protein (RBB) gene and controls DNA replication. The cotton RBB gene has features similar to most plant genes such as regions that code for protein separated by noncoding regions. The RBB gene is highly expressed in regions of the plant where the cells are dividing and also is expressed late in cotton fiber development when about 20% of cotton fibers are replicating their genes. The RBB gene is a good candidate for controlling DNA replication in cotton fibers and its identification represents a first step in determining if DNA replication is associated with lack of uniformity.

Technical Abstract: A genomic clone representing a putative retinoblastoma binding protein was isolated from a Gossypium hirsutum BAC library. The sequence of the gene identified six introns having standard eukaryotic slice junctions. The conceptual spliced transcript was 98% identical to TC37171 in the TIGR gene index, however it encoded an ORF translating protein 107 amino acids longer than TC37171. The conceptual translation of the genomic clone was 56% identical to a tomato gene experimentally demonstrated to be a retinoblastoma binding protein and able to complement the yeast growth mutant IRA. The mRNA encoded by the genomic clone was abundantly expressed in meristems, and expression levels increased as the cotton fiber matured. We propose that this gene may regulate growth and/or cell division in cotton based on homology of the clone with a protein of known function and sites of expression.