Spatial and temporal divergence of expression in duplicated barley germin-like protein-encoding genes.
Subfunctionalization is the process by which a pair of duplicated genes, or paralogs, experiences a reduction of individual expression patterns or function while still reproducing the complete expression pattern and function of the ancestral gene. Two germin-like protein (GLP)-encoding genes, GerB and GerF, are paralogs that belong to a small gene family in barley (Hordeum vulgare). Both genes share high nucleotide sequence similarity in coding and noncoding regions and encode identical apoplastic proteins. The use of RNA gel blots, coupled with single-stranded conformation polymorphism (SSCP) analysis of RT-PCR products, elucidated the developmental and tissue-specific expression patterns of each gene. Individual expression patterns provided evidence of both overlapping redundancy and early subfunctionalization. GerB is predominantly expressed in developing shoots, while GerF is predominantly expressed in seedling roots, developing spikes, and pericarp/testa. GerF promoter deletion studies located a region (-356/-97) responsible for high promoter activity and showed the ability of GerB and GerF upstream regions to drive gfp expression in coleoptiles, epicarps, and lemma/palea of developing spikes. The observed expression patterns are consistent with proposed roles in plant development and defense mechanisms for this gene family. These roles may explain why redundancy has been selectively maintained in this duplicate gene pair.
Federico
Maria L
ML
Department of Agronomy, University of Wisconsin, Madison, Wisconsin 53706, USA.
Iñiguez-Luy
Federico L
FL
Skadsen
Ronald W
RW
Kaeppler
Heidi F
HF
D001483:Base Sequence; D018076:DNA, Complementary / Q000032:analysis; D005670:Fusarium / Q000472:pathogenicity; D020440:Gene Duplication; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism*; D006066:Gonads / Q000378:metabolism; D001467:Hordeum / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D018807:Polymorphism, Single-Stranded Conformational; D011401:Promoter Regions, Genetic; D014018:Tissue Distribution
D018076:DNA, Complementary; D006023:Glycoproteins; D010940:Plant Proteins