Homologous Recombination and Gene Silencing in Plants

Higher eukaryotes are characterized by the allocation of distinct functions to numerous types of differentiated cells. Whereas in animals the well-defined, protected cells of the germ line separate early, germ cells in plants differentiate from somatic cells only after many cycles of mitotic division. Therefore somatic mutations in plants can be transmitted via the germ cells to the progeny. There is thus a clear need for somatic tissues to maintain their genetic integrity in the face of environmental challenges, and two types of interactions have been shown to play important roles in the conservation as well as flexibility of plant genomes: homologous recombination of repeated sequences and silencing of multiplied genes. Sensitive methods have been developed that allow greater insights into the dynamics of the genome. This book summarizes current knowledge and working hypotheses about the frequencies and mechanisms of mitochondrial, plastid, nuclear and viral recombination and the inactivation of repeated genes in plants. Despite rapid developments in the field, it is often not possible to provide final answers. Thus, it is an additional task of this book to define the open questions and future challenges.
The book is addressed to scientists working on plant biology and recombination, to newcomers in the field and to advanced biology students.

Inhalt

1. Genetic RNA-RNA recombination in positive-stranded RNA viruses of plants.- 2. Recombination of a plant pararetrovirus: Cauliflower mosaic virus.- 3. Recombination in geminiviruses: Mechanisms for maintaining genome size and generating genomic diversity.- 4. Recombination of plant mitochondrial genomes.- 5. Homologous recombination and integration of foreign DNA in plastids of higher plants.- 6. Intrachromosomal recombination between genomic repeats.- 7. Substrate specificity of plant recombinases determined in extra-chromosomal recombination systems.- 8. Plant genes and proteins involved in homologous recombination.- 9. Homology recognition during T-DNA integration into the plant genome.- 10. Gene replacement in plants.- 11. Use of site-specific recombination systems in plants.- 12. Inactivation of repeated genes DNA-DNA interaction?.- 13. Post-transcriptional inhibition of gene expression: Sense and anti-sense genes.- 14. Silencing of chitinase expression in transgenic plants: An autoregulatory model.- 15. Inactivation of maize transposable elements.