The Regulation of Chromosome Axis formation in Plant Meiosis

Lead Research Organisation: University of Birmingham
Department Name: Sch of Biosciences

Abstract

In all sexually reproducing eukaryotes, meiotic recombination is essential for the maintenance of the ploidy level of the species, and the introduction of genetic variation. Both require genetic crossovers (COs) formed during meiosis.
The first step in CO formation is the production of double strand breaks (DSBs) in DNA. In many species, the number of DSBs produced far outweighs the number of COs that eventually resolve; in Arabidopsis thaliana, approximately 5% of DSBs will become COs. Several levels of control on CO frequency and distribution have previously been elucidated. In many cereal species such as Wheat, these stringent controls on recombination result in up to 50% of the genetic information being inaccessible to plant breeders.
It is still not fully understood how the decision to make a CO is made, but it is known that the interaction between the recombination machinery, the chromosome axis, and the global remodelling of chromosomes during meiosis is crucial. Investigating the role of the chromosome axis in meiosis is therefore essential if we are to learn how we might manipulate meiotic recombination, and allow crop breeders to more rapidly develop new, improved cultivars. Through a combination of innovative molecular and cytogenetic techniques, this PhD project aims to further our understanding of the role of the chromosome axes in meiosis, and how individual proteins are regulated. This will include investigation of the protein-protein interactions and post-transcriptional modifications that may influence the regulation and role of several core axis proteins, as well as the use of super-resolution microscopy to visualise the axis in greater detail.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
BB/M01116X/1 01/10/2015 30/09/2023
1644151 Studentship BB/M01116X/1 05/10/2015 30/09/2019 Alice Darbyshire
 
Description ASY4 is a crucial component of the meiotic chromosome axis in the plant model organism Arabidopsis thaliana. We published one version of a mutant with Mathilde Grelon's group at the INRA Versailles that I prove is a hypomorphic mutant, that is, it is not a true null mutant of ASY4. Thus, using CRISPR/Cas9, I have developed a true ASY4-null mutant.
I present a different phenotype to that observed with Grelon et al., the results of which I anticipate in these last few months of my PhD.
Exploitation Route The antibodies I produced and verified are now a stock that can be shared within the meiosis community worldwide.
My results show that ASY4/ASY3 are executing similar roles to SYCP1/SYCP2 in mouse, which will for other groups suggest further avenues of research.
If my mutant appears to have altered crossover (CO) localisation, then this would be useful for plant breeders, as the entire point of my research is to better understand the processes that govern where COs are deposited; this is so breeders can access the areas of the genome in crops that may contain useful variants of genes, or indeed, to break up the linkage between unfavourable alleles and favourable ones.
Sectors Agriculture, Food and Drink,Other

 
Description ASY4 
Organisation French National Institute of Agricultural Research
Department INRA Versailles
Country France 
Sector Academic/University 
PI Contribution Cytology: analysis of mutant lines, and complemented mutant lines. Our group was solely responsible for production of an eYFP tagged plant line, and all the associated analysis. We also contributed to the writing of the associated paper. We initially identified the protein independently. Development of the asy4-4 CRISPR/Cas9 knock-out mutant line. All analysis of said line.
Collaborator Contribution INRA: Initial analysis of mutant plant lines, independently discovered the protein. Obtained the mutant lines. Wrote the majority of the paper. Gave us the original seeds. Cytological analysis, and RT-PCR. IPK: Invited by Dr Stefan Heckmann to learn techniques, free of charge, in his laboratory. JIC: Prof Kirsten Bomblies allowed me to use their SIM Microscope free of charge for three days to image cells from this project.
Impact INRA: Identification of ASYNAPTIC4, a Component of the Meiotic Chromosome Axis. Published in Plant Physiology 2018. JIC: Publication currently being written.
Start Year 2015
 
Description ASY4 
Organisation IPK Gatersleben
Country Germany 
Sector Private 
PI Contribution Cytology: analysis of mutant lines, and complemented mutant lines. Our group was solely responsible for production of an eYFP tagged plant line, and all the associated analysis. We also contributed to the writing of the associated paper. We initially identified the protein independently. Development of the asy4-4 CRISPR/Cas9 knock-out mutant line. All analysis of said line.
Collaborator Contribution INRA: Initial analysis of mutant plant lines, independently discovered the protein. Obtained the mutant lines. Wrote the majority of the paper. Gave us the original seeds. Cytological analysis, and RT-PCR. IPK: Invited by Dr Stefan Heckmann to learn techniques, free of charge, in his laboratory. JIC: Prof Kirsten Bomblies allowed me to use their SIM Microscope free of charge for three days to image cells from this project.
Impact INRA: Identification of ASYNAPTIC4, a Component of the Meiotic Chromosome Axis. Published in Plant Physiology 2018. JIC: Publication currently being written.
Start Year 2015
 
Description ASY4 
Organisation John Innes Centre
Country United Kingdom 
Sector Academic/University 
PI Contribution Cytology: analysis of mutant lines, and complemented mutant lines. Our group was solely responsible for production of an eYFP tagged plant line, and all the associated analysis. We also contributed to the writing of the associated paper. We initially identified the protein independently. Development of the asy4-4 CRISPR/Cas9 knock-out mutant line. All analysis of said line.
Collaborator Contribution INRA: Initial analysis of mutant plant lines, independently discovered the protein. Obtained the mutant lines. Wrote the majority of the paper. Gave us the original seeds. Cytological analysis, and RT-PCR. IPK: Invited by Dr Stefan Heckmann to learn techniques, free of charge, in his laboratory. JIC: Prof Kirsten Bomblies allowed me to use their SIM Microscope free of charge for three days to image cells from this project.
Impact INRA: Identification of ASYNAPTIC4, a Component of the Meiotic Chromosome Axis. Published in Plant Physiology 2018. JIC: Publication currently being written.
Start Year 2015
 
Description A-Level Revision Podcasts 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact Podcasts developed and made available to people worldwide who wish to know more about certain topics in biology, but was especially targeted at A-Level students wishing to know more about research.
Year(s) Of Engagement Activity 2016
URL https://www.birmingham.ac.uk/undergraduate/preparing-for-university/stem/STEM-resources.aspx?utm_sou...
 
Description MEICOM Meet The Scientist 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Along with the students from the MEICOM network, we executed a 'Meet The Scientist' event at the Think Tank Museum, Birmingham, during the February half term.
Thousands of people were expected to visit on this day.
Year(s) Of Engagement Activity 2019
 
Description University of The Third Age 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact The Science Branch of The University of The Third Age arrange a monthly talk. After approaching them, they agreed to let me speak to them about the uses of gene editing technologies and meiosis research to contribute toward ensuring food security in the future. The full cohort attended, which is 10 people. My aim was to both alert them to the issues surrounding food security, and to find out how much they knew about GE technologies, with focus on CRISPR/Cas9. The idea was to give an unbiased discussion that was purely informational, and determine if there had been a shift in opinion without any biased input. They were surveyed before hand. Only two said they would eat a GM crop. After the talk, 9 said they would. They also fed back that they had not realised the importance of meiosis research, and how GE/GM open up a lot more possibilities for plant breeders. They said they would ensure they spoke to their friends about GM, as some felt strongly that the media had been painting a negative picture of the technology. No media engagement. No external resources were required.
Year(s) Of Engagement Activity 2016
 
Description UoB School 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact I approached the University of Birmingham School to give a talk to A-Level students on my research. These students had signed up to a lunchtime workshop where they could hear from PhD students and other researchers about their experiences, including how to get into university in the first place. Around 30 people attended. I spoke about my academic progression, and gave advice on their future choices, funding etc. I then went on to discuss meiosis in-depth: they had not yet covered in their lessons that the chromosomes have an axis, nor anything to do with how COs are not uniformly distributed throughout the genome, and the problems that arise because of it. The teachers said it would supplement the pupils' understanding of meiosis, and also, could potentially influence their teaching of the topic.
Year(s) Of Engagement Activity 2015