Submitted to: Molecular Biology Reports
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/6/2009
Publication Date: 3/15/2009
Citation: Taliercio, E.W., Ray, J.D., Scheffler, J.A. 2009. Isolation and characterization of a cotton cdh-like gene. Molecular Biology Reports. Interpretive Summary: Cotton fibers elongate without dividing to form economically valuable spinnable fiber. It is clear that fibers almost never divide however reports on synthesis of DNA in fibers are variable. An early report indicated the genome size increased at the beginning of fiber development but later reports are generally consistent with a low level of DNA synthesis in cotton fibers cells. A cotton gene was sequenced and analyzed that potentially played a role in control of cell division. This gene was similar to a gene in alfalfa that was associated with late events in the cell cycle and was associated with an increase in genomic DNA in some cell types. Generally this gene, called Ghcdh, in cotton was also expressed in tissues with increased DNA synthesis but not in fiber cells. Low levels of expression of this gene in fibers were consistent with lower levels of DNA in fibers cells. We note however that this Ghcdh1 expression was not absolutely correlated with DNA synthesis in meristems and leaves suggesting it may also play other roles in cotton. A potentially useful molecular marker was identified for this gene.
Technical Abstract: Cotton fiber cells elongate without dividing to form economically valuable spinnable fiber. Reports of the ploidy level of fiber cells are variable. Early reports on young fibers indicated an increase in nuclear DNA content; however, subsequent reports failed to observe such a significant increase in ploidy level. Evaluation and analysis of genes involved in regulation of DNA synthesis and other aspects of cell cycle regulation identified relevant genes that were present in fiber cells though usually at low levels. We report the isolation and characterization of another gene likely to be involved in cell cycle/DNA synthesis control. This gene was similar to a Medicago gene that controls entry into anaphase by regulating the activity of the anaphase promoting complex ability to ubiquinate selected proteins. The cotton gene was composed of 9 exons and the deduced translation has motifs similar to a Medicago gene expressed in highly polyploid cells. Based on this similarity the cotton gene was designated Ghcdh. Ghcdh is highly expressed in meristems and leaves but is present at much lower levels in fiber cells. These data are consistent with the lower levels of polyploidy reported for cotton fiber. A simple sequence repeat (SSR) was identified in the gene that may be exploited as a marker to map this gene.