Control of meiotic recombination in plants

Aloufi, Salman (2019). Control of meiotic recombination in plants. University of Birmingham. Ph.D.

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This project aims to locate the DNA-PKcs in Arabidopsis thaliana and identify the role by analysing Atdna-pkcs mutants. The silico, genetic and cytology data for DNA-PKCs in Arabidopsis thaliana showed that putative AtDNA-PKa and putative AtDNA-PKb are the two genes of AtDNA-PKcs in Arabidopsis thaliana. The expression data for both genes proves that AtDNA-PKCs are expressed in different tissues, but the strongly expressed in flower buds particularly in opened buds. Also, AtDNA-PKcs were expressed in male and female organs with more expression in the female organs. The data collected of double homozygous mutants suggests that Atdna-pkcs is sterile null mutant, AtDNAPKcs do not play any role in meiosis, but could be important after meiosis or in mitosis to repair DSBs through NHEJ as proves by pollen grain reduction, some anaphase bridges during mitosis, and the effect of DNA damage agents on the growth of the atdnapkcs plants.
This project also aimed to study the outcome of residual DSB during meiosis in Arabidopsis thaliana. Genetic and cytology analysis was performed for Atprd2 homozygous mutant and induced DSBs by cisplatin in the absence of AtSPO11-2. The result collected demonstrates some DSB formation is observed through the presence of yH2AX foci, These DSBs are repaired by HR and producing some crossovers, and some clear rod bivalents are showed in metaphase I. However, these data suggested that partly synapsis between homologous chromosomes can produce COs through meiotic recombination machinery. Thus, study Zinc Finger Nucleases (ZFNs) has used to induce DSBs in specific sequences in the Arabidopsis thaliana genome (on TT4 and ADH1 loci) in an Atspo11.2 null mutant background. Inducible system has used to express the ZFNs and produce a specific targeted DSB during meiosis has allowed us to study the different outcomes of these DSBs. This data of induced DSBs by ZFN indicated that targeted DSB could be synopsised and repaired by meiotic recombination machinery and initiate homologous pairing and recombination in that genomic region. Nevertheless, because the sequence recognised by the ZFNs is present in both homologous chromosomes and both sister chromatids, it could produce DSBs in all these regions which would not be possible to be processed by the meiotic recombination machinery and would produce some fragmentations. This thesis will produce new insights into the control of meiotic recombination in plants.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Licence: All rights reserved
College/Faculty: Schools (1998 to 2008) > School of Biosciences
School or Department: School of Biosciences
Funders: Other
Other Funders: Saudi Arabia Cultural Bureau in London
Subjects: Q Science > Q Science (General)


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