Research:Rowan
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Meiotic Recombination
Introduction
One of the advantages of sexual reproduction is the possibility to generate new combinations of alleles. During meiotic recombination, genetic information is swapped between the maternal and paternal chromosomes. This can lead to the expression of new traits. The positions of these genetic exchanges, known as crossovers, occur on average 1-2 times per chromosome across a diverse range of organisms. However, not all positions along a chromosome have an equal probability of crossing over. The patterns of large and fine scale "hotspots" and coldspots" have been the subject of much research in different biological fields.
I am using the model plant, Arabidopsis thaliana, to investigate the genetic factors that influence the position of crossovers at a genome-wide scale. A crossover is generated when the homologous chromosome is used to repair a double-strand break. Although hundreds of double-strand breaks are purposely initiated by the cells that go on to form gametes during meiosis, the vast majority are repaired using mechanisms that do not result in crossovers.
Understanding Recombination
Through my research, I have developed new approaches to study where and when crossovers occur using next-generation sequencing. The advantage of this approach is that it provides information at high resolution for every position in the genome.
Questions
These are main questions I would like to answer:
- Which proteins promote the formation of crossovers?
- Which proteins restrict the formation of crossovers?
- What are the mechanisms by which these proteins act?
- What are the interactions among proteins that participate in different repair pathways?
- Which of these proteins are conserved or variable across different evolutionary timescales?
and ultimately
- What determines whether a double strand break will be repaired as a crossover or a non-crossover?
Manipulating Recombination
Once I know more about the proteins that are involved in crossovers, I can experimentally manipulate their activity. By employing this strategy, I can seek answers to the following questions:
Questions
General
- Do factors that increase the frequency of crossovers also affect the distributions?
- Can coldspots be converted into hotspots and vice versa?
Mapping traits
Many scientists are interested in understanding which genes produce which traits. If the trait is quantitative (varies continuously in a population), then a technique known as Quantitative Trait Locus (QTL) mapping is employed. This technique takes advantage of recombination to identify which parts of the genome are associated with a given trait.
- Can manipulating recombination enhance QTL mapping?
Crop breeding
Crops have been improved by humans for centuries by taking advantage of recombination and artificial selection. Since recombination does not happen uniformly across the genome, this creates blocks of genes that are inherited together.
- Can altering recombination be used to prevent linked traits from being inherited together?
Evolutionary Implications
Since recombination can create new combinations of alleles, it can produce traits that did not exist in the parental generation. These "new" traits can then be subject to natural selection.
- What affect does altering the recombination rate have on the fitness of populations growing in the field
Experimental Evolution
Altering recombination rates may also influence the efficiency of natural selection. One way to investigate this would be by using artificial selection to experimentally evolve different traits.
- How does the rate of recombination affect the ability to select for adaptation to stress?
