Coordinated and fine-scale control of homoeologous gene expression in allotetraploid cotton.

Within polyploid plant species, it has been demonstrated that homoeologous genes (genes duplicated by polyploidy) often display dynamic expression patterns. To determine if chromosomal location plays a role in establishing these expression patterns, we analyzed the relative levels of homoeolog expression among linked genes from 2 locations in the cotton genome. Genes from the region containing the alcohol dehydrogenase A gene show coordinated expression across several tissues, whereas genes from the region containing cellulose synthase A do not. These results indicate that changes in homoeolog expression may be constrained by linkage in some genomic regions, whereas in other regions, homoeolog expression is largely decoupled from physical proximity. Furthermore, these results suggest that both large- and small-scale regulatory mechanisms may control homoeolog expression patterns.