Unlike most organisms where the structure of the chromosomes (the karyotype) is relatively stable, in the fungus Microbotryum there is enormous variation in chromosome size and the DNA content from one generation to the next. Even within an individual, there can be large differences between its two chromosome sets. The reasons for this variation appear to be related to the reproductive system of the fungus where mating occurs among the gametes produced by one precursor cell (automixis). This mating system is very similar to that found in many other fungi, plants, and insects. This study will examine the consequences of changes in genomic structure for offspring viability, as well as the correlations between chromosome variation and the proportion of the genome consisting of highly repetitive sequences of DNA.
Understanding the dynamics of genetic variation is the basis not only for interpreting evolutionary processes, but also for rational approaches to plant and animal breeding and population management for conservation, disease prevention, and control of invasive species. Furthermore, even small changes in chromosome structure are frequently associated with severe abnormalities in humans and other systems. This study will help identify genetic processes that allow some organisms to cope and even adapt to genomic instability.
