Presence in the double dose renders some recessive genes lethal to development. As evolution has preserved these genes, logic suggests that the single version of the allele is important in cell function or overall development. Studying the function of these lethal genes is difficult as homozygous plants are not viable. However, the 'Uncovering the postembryonic function of embryonic lethal genes in Arabidopsis thaliana' (CLONAL) project is studying the role of lethal genes using techniques involving clonal analysis.The scientists created areas (sectors) of clonally-related mutant cells in an otherwise normal Arabidopsis thaliana (thale cress) plant. Despite creating hundreds of lethal mutants in Arabidopsis and other plant species, the genes involved have not been matched with their functions. CLONAL researchers selected 35 thale cress embryo-lethal mutants carrying an emb allele that affects leaf development. The focus is on genes with possible regulatory roles in gene expression. Irradiating with X-rays and selectively inserting green fluorescent protein-marked mutants in the genome, the team generated different embryo-lethal mutations. The genes were transferred to appropriate Agrobacterium strains to generate doubly transgenic plants that can be crossed with heterozygous plants (EMB/emb). Using this state-of-the-art genomics, CLONAL have generated 31 different lines with all the elements for sector induction. Interestingly, plants homozygous for an emb mutation (emb/emb) were isolated but were able to grow despite their embryo-lethality, so-called "escapers". The relevance of this discovery for plant development is the subject of a paper in 'Trends in Plant Science'. Ongoing studies after the project will elucidate the role of these genes in the development of the adult body of the plant. Such studies can provide novel insight into plant development for applications in biotech and agriculture.
Lethal genes, homozygous, Arabidopsis thaliana, clonal analysis, mutant, embryo-lethal, transgenic, heterozygous