Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/22/2005
Publication Date: 1/13/2006
Citation: Federico, M.L., Iniguez-Luy, F.L., Skadsen, R.W., Kaeppler, H.F. 2006. Spatial and temporal divergence of expression in duplicate barley GLP-encoding genes. 14th Annual Plant and Animal Genome Conference Proceedings. p. 334.
Technical Abstract: Subfunctionalization is the process by which a pair of duplicate genes, or paralogs, experiences a reduction of individual expression patterns while still maintaining the complete expression pattern of the ancestral gene. Two germin-like protein (GLP) encoding genes, GerB and GerF, are paralogs which belong to a small family of similar genes in barley. Both share high DNA sequence homology in coding and non-coding regions. They also encode identical proteins that are deposited between the cell wall and the cell plasma membrane. DNA sequence studies indicate that this gene pair is likely changing, but they are changing in ways that will preserve the function of the encoded proteins. Individual expression patterns for each gene provided evidence of both overlapping redundancy of expression and early subfunctionalization (specialization). GerB is predominantly expressed in developing shoots; while GerF is predominantly expressed in seedling roots, developing spikes and pericarp/testa. The DNA sequence of the promoter region that is responsible for turning on the gene was determined. This sequence was cloned and showed the ability of to drive reporter gene (gfp) expression in the proper tissues. This ability, and the inducible response pattern exhibited by these duplicate genes under Fusarium graminearum infection, make these promoters useful candidates for targeting transgene-mediated resistance in barley. In addition, GerB and GerF expression patterns are consistent with proposed roles in plant development and defense mechanisms for this gene family. These roles may explain why two similar genes have been selectively maintained. These studies will benefit other scientists involved in the study of barley and other cereal genomes.