The spatial regulation of Auxin Response Factors
Auxin regulates plant growth and development through the transcription factors (TFs) of the AUXIN RESPONSE FACTOR (ARF) gene family. Class A ARFs, ARF5, 6, 7, 8 and 19 are transcriptional activators, and control many developmental processes. However, we only have limited understanding on how these A...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English |
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2021
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| Online Access: | https://eprints.nottingham.ac.uk/66997/ |
| _version_ | 1848800376164188160 |
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| author | Jingyi, Han |
| author_facet | Jingyi, Han |
| author_sort | Jingyi, Han |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | Auxin regulates plant growth and development through the transcription factors (TFs) of the AUXIN RESPONSE FACTOR (ARF) gene family. Class A ARFs, ARF5, 6, 7, 8 and 19 are transcriptional activators, and control many developmental processes. However, we only have limited understanding on how these ARFs can mediate such diverse developmental responses. In this study we investigated expression patterns of ARFs in the root and shoot apical meristems and showed that they have specific domains of expression. Through a yeast one-hybrid and protoplast assay, we identified a network of transcriptional repressors which regulated these ARFs. To validate this network, we over-expressed candidate TFs in ARF reporter lines, generated new reporter lines to check the co-expression of TFs and ARFs in specific tissues and carefully quantified auxin specific phenotypes in the mutants of candidate TFs. Collectively, these results support a mechanism in which the spatial and temporal expression of ARFs is modulated mainly by tissue specific repression.
In order to understand ARF promoter specificity in auxin responses in the most efficient manner, we saw the opportunity to improve the mechanism for creating reporter constructs. In order to improve live imaging of gene expression in its geometric context, we developed a new series of lines (DEAL) showing cellular anatomy which can efficiently combine with auxin sensors and other reporters by Greengate cloning.
Analysing the 5 ARF reporter lines, we found ARF7 has an interesting expression pattern. A broad expression of ARF7 was observed in root tips only in the reporter containing an in-frame fusion of GFP from 3kb promoter to the second exon. Whilst this region upstream of the transcriptional start site had no effect on expression in the shoot. I demonstrated that the first intron plays an important role in transcriptional regulation in the root meristem. A swap experiment in which the first intron was moved to the 5’-UTR showed the position of intron is not essential for the correct expression. Therefore, we propose that it is the sequence within this intron that is required and that key transcription factors bind to this region. Bioinformatic analysis into potential binding sites within this promoter suggests that NACs and MYBs bind in this intron to regulate ARF7 expression in the root apical meristem. Collectively these data support a role in which root- and shoot-specific binding motifs coordinate the elaborate expression patterns of ARFs. |
| first_indexed | 2025-11-14T20:50:34Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-66997 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T20:50:34Z |
| publishDate | 2021 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-669972023-12-08T04:30:26Z https://eprints.nottingham.ac.uk/66997/ The spatial regulation of Auxin Response Factors Jingyi, Han Auxin regulates plant growth and development through the transcription factors (TFs) of the AUXIN RESPONSE FACTOR (ARF) gene family. Class A ARFs, ARF5, 6, 7, 8 and 19 are transcriptional activators, and control many developmental processes. However, we only have limited understanding on how these ARFs can mediate such diverse developmental responses. In this study we investigated expression patterns of ARFs in the root and shoot apical meristems and showed that they have specific domains of expression. Through a yeast one-hybrid and protoplast assay, we identified a network of transcriptional repressors which regulated these ARFs. To validate this network, we over-expressed candidate TFs in ARF reporter lines, generated new reporter lines to check the co-expression of TFs and ARFs in specific tissues and carefully quantified auxin specific phenotypes in the mutants of candidate TFs. Collectively, these results support a mechanism in which the spatial and temporal expression of ARFs is modulated mainly by tissue specific repression. In order to understand ARF promoter specificity in auxin responses in the most efficient manner, we saw the opportunity to improve the mechanism for creating reporter constructs. In order to improve live imaging of gene expression in its geometric context, we developed a new series of lines (DEAL) showing cellular anatomy which can efficiently combine with auxin sensors and other reporters by Greengate cloning. Analysing the 5 ARF reporter lines, we found ARF7 has an interesting expression pattern. A broad expression of ARF7 was observed in root tips only in the reporter containing an in-frame fusion of GFP from 3kb promoter to the second exon. Whilst this region upstream of the transcriptional start site had no effect on expression in the shoot. I demonstrated that the first intron plays an important role in transcriptional regulation in the root meristem. A swap experiment in which the first intron was moved to the 5’-UTR showed the position of intron is not essential for the correct expression. Therefore, we propose that it is the sequence within this intron that is required and that key transcription factors bind to this region. Bioinformatic analysis into potential binding sites within this promoter suggests that NACs and MYBs bind in this intron to regulate ARF7 expression in the root apical meristem. Collectively these data support a role in which root- and shoot-specific binding motifs coordinate the elaborate expression patterns of ARFs. 2021-12-08 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en cc_by https://eprints.nottingham.ac.uk/66997/1/The%20spatial%20regulation%20of%20Auxin%20Response%20Factors-correction%20version211021.pdf Jingyi, Han (2021) The spatial regulation of Auxin Response Factors. PhD thesis, University of Nottingham. Auxin Plant growth Transcription factors TFs Auxin Response Factors ARF Plant genetics |
| spellingShingle | Auxin Plant growth Transcription factors TFs Auxin Response Factors ARF Plant genetics Jingyi, Han The spatial regulation of Auxin Response Factors |
| title | The spatial regulation of Auxin Response Factors |
| title_full | The spatial regulation of Auxin Response Factors |
| title_fullStr | The spatial regulation of Auxin Response Factors |
| title_full_unstemmed | The spatial regulation of Auxin Response Factors |
| title_short | The spatial regulation of Auxin Response Factors |
| title_sort | spatial regulation of auxin response factors |
| topic | Auxin Plant growth Transcription factors TFs Auxin Response Factors ARF Plant genetics |
| url | https://eprints.nottingham.ac.uk/66997/ |