The plasticity of the plant genome permits the tissue to change from one form of development to another. Once the developmental fate is determined, a series of morphological changes result that are accompanied by sequential changes in gene expression. The mechanism of the developmental switch is poorly understood, except that major genomic reprogramming might occur. Recently, the PI found that late embryogenesis abundant (LEA) genes are activated at the onset of embryogeny from the zygote, from cultured microspores and from cultured leaf tissue. This result suggests that the embryonic switch involves a global derepression or activation of a battery of genes including both early and late embryonic genes. To substantiate this hypothesis, the PI proposes to study the mechanisms of gene expression at the onset of embryogenesis. Experiments are designed to compare the mechanisms by which a LEA gene, DC8, is expressed at early and late embryogeny, and to identify the genes involved in the activation of the DC8 promotor.
