Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Mating type and pheromone genes in the Gibberella fujikuroi species complex : an evolutionary perspective
Dissertation (MSc)--University of Pretoria, 2011.
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Published: |
University of Pretoria
2013
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613515885314048 |
|---|---|
| access_status_str | Open Access |
| author2 | Wingfield, Brenda D. |
| author_browse | Wingfield, Brenda D. |
| author_facet | Wingfield, Brenda D. |
| collection | Thesis |
| dc_rights_str_mv | © 2011 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc)--University of Pretoria, 2011. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/27679 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:37:22.997Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/27679 Mating type and pheromone genes in the Gibberella fujikuroi species complex : an evolutionary perspective Wingfield, Brenda D. simon.martin@fabi.up.ac.za Steenkamp, Emma Theodora Wingfield, Michael J. Martin, Simon Henry Mating type Gibberella fujikuroi species Pheromone genes UCTD Dissertation (MSc)--University of Pretoria, 2011. Reproductive isolation is an essential stage in speciation. In Ascomycetes, the ubiquitous distribution of many species suggests that sympatric speciation through assertive mating should be an important factor. The MAT locus and the pheromone/receptor system could both potentially contribute to the development of such sexual isolation. Alterations at the MAT loci could lead to distinct reproductive habits or a change in mating system, both of which can reduce gene-flow between species. However, if deliberate pre-mating sexual preferences exist, they are more likely to be determined by the pheromone/receptor system. This study of Fusarium reproductive genes, and comparisons with other Ascomycetes, has yielded numerous interesting findings regarding the evolution of these mate-recognition mechanisms and the implications thereof. The G. fujikuroi and F. graminearum species complexes have offered an interesting comparison between heterothallic and homothallic MAT locus evolution. The value of comparative sequence analysis has been demonstrated in the discovery of a previously unknown gene, MAT1-2-3, which may be specific to members of the Order Hypocreales. While all MAT genes share similar regulatory elements, this is the first report of evidence that a transition to homothallism can be accompanied by the recruitment of distinct elements that could facilitate alternate expression of MAT genes. The MAT genes are also highly divergent between Fusarium spp., largely due to relaxed selective constraint, particularly in homothallic species. However, inter-specific gene-flow could curb MAT gene divergence among homothallic species. Despite strong reproductive barriers in the G. fujikuroi complex, the F. sacchari MAT1-1 sequence appears to have been acquired through lateral transfer from a distant relative. Analytical analysis of the MAT locus novelties reported here, including the new MAT gene, will be necessary to determine their biological significance. To investigate the extent of pheromone diversity in the Ascomycetes, and to gain clues as to its biological importance, pheromone peptides from seventy ascomycete species were compared. A number of reproductively incompatible species, such as those in the G. fujikuroi complex, share identical pheromones; which implies that another mechanism must be responsible for the observed reproductive barriers. However, on the whole, pheromones are highly divergent among species. Both adaptive and non-adaptive evolution could have contributed to this pattern. In fact the structure of the á-class pheromone precursor gene, which consists of multiple repeats of the pheromone module, could facilitate rapid diversification through “birth-and-death” evolution. Within species, selection maintains pheromone peptides, implying that much of the inter-specific variation is functionally relevant. This further suggests that pheromone evolution could contribute to the generation of reproductive isolation between species. The most general trend in the findings of this study is that ascomycete reproductive genes are highly divergent. This is in agreement with findings in other Kingdoms. A number of evolutionary forces are probably involved but weaker selective constraint, resulting from the fact that reproduction is not essential in these fungi, appears to be a common factor. This reproductive gene variability could be directly linked to speciation and, therefore, the great diversity in Ascomycetes. Additional information on the appendices is available on a CD, stored at the Merensky Library on Level 3 Genetics Unrestricted 2013-09-07T12:00:42Z 2011-09-08 2013-09-07T12:00:42Z 2011-04-07 2011-02-08 2011-09-01 Dissertation Martin, Simon Henry 2011, Mating type and pheromone genes in the Gibberella fujikuroi species complex : and evolutionary perspective, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/27679 > E11/405/gm http://hdl.handle.net/2263/27679 http://upetd.up.ac.za/thesis/available/etd-09012011-170054/ © 2011 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Mating type Gibberella fujikuroi species Pheromone genes UCTD Mating type and pheromone genes in the Gibberella fujikuroi species complex : an evolutionary perspective |
| title | Mating type and pheromone genes in the Gibberella fujikuroi species complex : an evolutionary perspective |
| title_full | Mating type and pheromone genes in the Gibberella fujikuroi species complex : an evolutionary perspective |
| title_fullStr | Mating type and pheromone genes in the Gibberella fujikuroi species complex : an evolutionary perspective |
| title_full_unstemmed | Mating type and pheromone genes in the Gibberella fujikuroi species complex : an evolutionary perspective |
| title_short | Mating type and pheromone genes in the Gibberella fujikuroi species complex : an evolutionary perspective |
| title_sort | mating type and pheromone genes in the gibberella fujikuroi species complex an evolutionary perspective |
| topic | Mating type Gibberella fujikuroi species Pheromone genes UCTD |
| url | http://hdl.handle.net/2263/27679 http://upetd.up.ac.za/thesis/available/etd-09012011-170054/ |