Differences in spatial expression between 14-3-3 isoforms in germinating barley embryos

The family of 14-3-3 proteins is ubiquitous in eukaryotes and has been show n to exert an array of functions. We were interested in the possible role o f 14-3-3 proteins in seed germination. Therefore, we studied the expression of 14-3-3 mRNA and protein in barley (Hordeum distichum L.) embryos during germination. With the use of specific cDNA probes and antibodies, we could detect individual expression of three 14-3-3 isoforms, 14-3-3A, 14-3-3B, a nd 14-3-3C. Each homolog was found to be expressed in barley embryos. Where as protein levels of all three isoforms were constant during germination, m RNA expression was round to be induced upon imbibition of the grains. The i nduction of 14-3-3A gene expression during germination was different from t hat of 14-3-3B and 14-3-3C. In situ immunolocalization analysis showed simi lar spatial expression for 14-3-3A and 14-3-3B, while 14-3-3C expression wa s markedly different. Whereas 14-3-3A and 14-3-3B were expressed throughout the embryo, 14-3-3C expression was tissue specific, with the strongest exp ression observed in the scutellum and the L2 layer of the shoot apical meri stem. These results show that 14-3-3 homologs are differently regulated in barley embryos, and provide a first step in acquiring more knowledge about the role of 14-3-3 proteins in the germination process.