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dc.contributor.authorCoimbatore Nageswaran, Divyashree
dc.date.accessioned2019-01-28T10:39:28Z
dc.date.available2019-01-28T10:39:28Z
dc.date.issued2019-05-18
dc.date.submitted2018-09-30
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/288432
dc.description.abstractMeiotic recombination promotes genetic variation by reciprocal exchange of genetic material producing novel allelic combinations that influence important agronomic traits in crop plants. Therefore, harnessing meiotic recombination has the potential to accelerate crop improvement via classical breeding. Numerous genes involved in crossover formation have been identified in model systems. For example, SPO11 mediates generation of meiotic DNA double-strand breaks (DSBs) across all eukaryotes, which may be repaired as crossovers. However, downstream regulators of recombination remain to be identified, including those with species-specific roles. To isolate crossover frequency modifiers I performed a high-throughput forward genetic screen using EMS mutagenesis of Arabidopsis carrying a fluorescent crossover reporter line called 420. The primary screen isolated nine mutants from ~3,000 scored individuals that showed significantly higher (high crossover rate, hcr) or lower (low crossover rate, lcr) crossover frequency, including a new fancm allele. Four mutants (hcr1, hcr2, hcr3 and lcr1) were mapped by sequencing and candidate genes identified. The hcr1 mutation was confirmed as being located within the PROTEIN PHOSPHATASE X-1 (PPX-1) gene, using isolation of an independent allele and complementation studies. Similarly, the lcr1 mutation was confirmed to be within the gene TBP-ASSOCIATED FACTOR 4B (TAF4B). Using immunocytological staining I observed that hcr1 did not show changes in DSB-associated foci (RAD51), but it did show a significant increase in crossover-associated MLH1 foci. The hcr1 mutation increases crossovers mainly in the sub-telomeric chromosome regions, which remain sensitive to crossover interference. Also the genetic interaction between the hcr1 and fancm mutations is additive. These results support a model where PPX- 1 acts to limit recombination via the Class I interfering CO pathway, downstream of DSB formation. In summary, this genetic screen has led to discovery of novel genes that regulate meiotic recombination and their functional characterization may find utility in crop breeding programs.
dc.description.sponsorshipMarie-Curie “COMREC” network FP7 ITN-606956
dc.language.isoen
dc.rightsAll rights reserved
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectMeiotic recombination
dc.subjectgenetic screen
dc.subjectmap-by-sequencing
dc.subjectgene characterization
dc.titleA forward genetic screen to identify factors that control meiotic recombination in Arabidopsis thaliana
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.publisher.departmentPlant Sciences
dc.date.updated2019-01-13T08:44:54Z
dc.identifier.doi10.17863/CAM.35722
dc.contributor.orcidCoimbatore Nageswaran, Divyashree [0000-0001-7548-3244]
dc.publisher.collegeDarwin
dc.type.qualificationtitlePhD in Plant Sciences
cam.supervisorR. Henderson, Ian
cam.thesis.fundingfalse
rioxxterms.freetoread.startdate2020-01-28


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