Current Genomics - Volume 3, Issue 6, 2002

Perhaps all flowering plants have experienced one or more episodes of polyploidization at some time in their evolutionary history. Recent evidence indicates that this genome doubling may be accompanied by a variety of non- Mendelian phenomena, some of which operate during hybridization and polyploid formation while others manifest more gradually on an evolutionary timescale. Here we review these phenomena, drawing Read More

Many of the proteins involved in meiotic recombination are conserved among eukaryotes, and here we discuss those recombination proteins that have been identified in plants. In addition, we summarize some of the differences in crossover regulation between plants and budding yeast (the primary model for molecular studies of recombination in eukaryotes). We also discuss factors that influence the distribution of crossover Read More

Telomeres and centromeres are the most important functional elements in plant chromosomes, as in other eukaryotic chromosomes. Both elements are in general composed of repetitive DNA sequences, and binding or associated proteins. Recent findings showed that the telomere DNA sequences are conserved among all plant species except Allium and related species, and that they form high-order complexes together Read More

The application of DNA-based phylogenies to the study of chromosome evolution has allowed the direction of many of the changes that give rise to the chromosome variation to be analysed objectively for the first time. Dysploid changes in chromosome number, differences in the degree of karyotype symmetry, the loss or gain of chromosome bands, changes in genome size and variation in the number of ribosomal RNA gen Read More

In land plants (Embryophyta), comprising bryophytes, pteridophytes, gymnosperms and angiosperms, DNA Cvalue data has increased significantly in recent years. Estimates are available for over 3,800 species, ranging over 2000- fold (1C = 0.06 - 127.4 pg). Evaluating the phylogenetic component of this variation is essential to understand its evolutionary significance. Consequently, C-value data were superimposed onto Read More

Nucleolar dominance is an enigma. The puzzle of differential amphiplasty has remained unresolved since it was first recognised and described in Crepis hybrids by Navashin in 1934. Here we review the body of knowledge that has grown out of the many models that have tried to find the genetic basis for differential rRNA gene expression in hybrids, and present a new interpretation. We propose and discuss a chromatin im Read More

Wheat is the most consumed grain crop in the world. It is also an excellent model of allopolyploid inheritance. Genomic analysis of wheat is essential for understanding the genetic mechanisms underlying allopolyploid evolution and speciation as well as the biology of agronomically important traits influencing production. In spite of the large genome and polyploidy, researchers have devised novel strategies for in de Read More