Genetic Analysis of Cytosolic PGI in Festuca ovina
(2003)- Abstract
- <i>Festuca ovina</i>, sheep's fescue is a widely distributed perennial outbreeder that belongs to the grass family Poaceae and is very common in the northern temperate zone. The genus <i>Festuca s.l.</i> is partitioned into fine-leaved fescues to which <i>F. ovina</i> belongs, and broad-leaved fescues to which the genus <i>Lolium</i> is a close relative. Wide crosses within the <i>Festuca-Lolium</i> complex often yield fertile hybrids. My thesis describes a genetic analysis of the variation for cytosolic phosphoglucose isomerase (PGI) in <i>Festuca ovina</i>. The investigation was initiated since an isozyme study demonstrated that some plants had multibanded... (More)
- <i>Festuca ovina</i>, sheep's fescue is a widely distributed perennial outbreeder that belongs to the grass family Poaceae and is very common in the northern temperate zone. The genus <i>Festuca s.l.</i> is partitioned into fine-leaved fescues to which <i>F. ovina</i> belongs, and broad-leaved fescues to which the genus <i>Lolium</i> is a close relative. Wide crosses within the <i>Festuca-Lolium</i> complex often yield fertile hybrids. My thesis describes a genetic analysis of the variation for cytosolic phosphoglucose isomerase (PGI) in <i>Festuca ovina</i>. The investigation was initiated since an isozyme study demonstrated that some plants had multibanded electrophoretic patterns that proved genetically uninterpretable. Chromosome analysis showed that the plants were not polyploid, but diploid with the standard number of 14 chromosomes. Classical genetic analysis based on artificial crosses revealed that a second PGI locus segregated in south-Swedish populations of <i>F. ovina</i>. The second locus (<i>PgiC2</i>) and the standard locus (<i>PgiC1</i>) assorted independently, <i>i.e.</i> were not linked. Sequence data revealed that the two loci were highly diverged. Moreover, <i>PgiC2</i> proved to be more complex than <i>PgiC1</i>, since all three <i>PgiC2</i> variants analysed were composed of two genes. One of these genes may be a pseudogene. The results demonstrate that <i>PgiC2</i> is not a simple, duplicated version of <i>PgiC1</i>. The sequences present today at these two loci must have started to diverge a long time ago, perhaps as far back as the time of the differentiation of the genus. I suggest that <i>PgiC2</i> entered <i>F. ovina</i> recently via an introgression event from another species in the <i>Festuca-Lolium</i> complex, where it normally functions as the "standard" locus for cytosolic PGI. This model is supported by the fact that alleles from <i>PgiC1</i> and <i>PgiC2</i> produce enzyme subunits that easily function together despite their wide sequence divergence. Thus, my thesis brings into focus a possible but not much discussed way for eukaryot organisms to add new genes to their genomes. (Less)
- Abstract (Swedish)
- Popular Abstract in Swedish
Mitt försöksmaterial utgjordes av <i>Festuca ovina</i>, fårsvingel, som är ett mycket vanligt gräs och tillhör familjen Poaceae. Fårsvingel är en perenn korsbefruktare och spridd över den tempererade zonen i Euroasien och Nordamerika. Släktet <i>Festuca</i> är uppdelat i smalbladiga svinglar, dit fårsvingel hör, och bredbladiga svinglar. Släktet <i>Lolium</i>, dit rajgräsen hör, är en nära släkting till de bredbladiga svinglarna. Korsningar mellan olika arter inom <i>Festuca-Lolium</i> komplexet resulterar ofta i fertila hybrider. Min avhandling beskriver genetisk analys av variation i ett enzym, cytosoliskt fosfoglukos isomeras (PGI), i <i>F.... (More) - Popular Abstract in Swedish
Mitt försöksmaterial utgjordes av <i>Festuca ovina</i>, fårsvingel, som är ett mycket vanligt gräs och tillhör familjen Poaceae. Fårsvingel är en perenn korsbefruktare och spridd över den tempererade zonen i Euroasien och Nordamerika. Släktet <i>Festuca</i> är uppdelat i smalbladiga svinglar, dit fårsvingel hör, och bredbladiga svinglar. Släktet <i>Lolium</i>, dit rajgräsen hör, är en nära släkting till de bredbladiga svinglarna. Korsningar mellan olika arter inom <i>Festuca-Lolium</i> komplexet resulterar ofta i fertila hybrider. Min avhandling beskriver genetisk analys av variation i ett enzym, cytosoliskt fosfoglukos isomeras (PGI), i <i>F. ovina</i>. Undersökningen initierades sedan en studie av isozymvariation i <i>F. ovina</i> visat att några plantor hade mångbandade elektroforesmönster som inte kunde tolkas genetiskt. Kromosomanalys visade att plantorna inte var polyploida, som man kunde förvänta sig, utan diploida med det normala antalet kromosomer (2n = 14). Klassisk genetisk analys baserad på kontrollerade korsningar visade att en andra PGI-gen segregerade i sydsvenska populationer av <i>F. ovina</i>. Den andra genen (<i>PgiC2</i>) och den normala genen (<i>PgiC1</i>) nedärvdes oberoende av varandra, det vill säga de var inte belägna nära varandra på samma kromosom. Mina sekvensanalyser av PGI visade att de två generna var mycket olika. Dessutom visade det sig att <i>PgiC2</i> var mycket mer komplext än <i>PgiC1</i>, eftersom alla de tre varianter av <i>PgiC2</i> som undersökts bestod av två kopplade gener. I ett fall var båda dessa kopplade gener aktiva och resulterade i två olika enzym, medan i de två andra fallen den ena genen resulterade i ett icke-fungerande protein och sålunda utgjorde en så kallad pseudogen. Eftersom de två generna är så olika tyder resultaten på att <i>PgiC2</i> inte är en inomartsduplikation av <i>PgiC1</i>. Istället måste de ha skilts åt för länge sedan och kanske kan ursprunget spåras ända till bildandet av själva familjen svinglar. Utifrån mina resultat verkar det troligt att <i>PgiC2</i> etablerades i <i>F. ovina</i> genom en korsningshändelse som involverade ett gräs från en annan art inom <i>Festuca-Lolium</i> komplexet. Den gen i <i>F. ovina</i> som jag betecknat <i>PgiC2</i> skulle i detta perspektiv vara den normala <i>PgiC</i> genen i denna än så länge okända gräsart. Min avhandling beskriver sålunda ett fenomen som sällan diskuteras, nämligen möjligheten att en växt kan inkorporera gener från en annan art. Detta har betydelse inte bara för praktiska ändamål, som till exempel växtförädling, men också för evolutionära och systematiska undersökningar. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/466413
- author
- Ghatnekar, Lena LU
- supervisor
- opponent
-
- Professor Charlesworth, Deborah
- organization
- publishing date
- 2003
- type
- Thesis
- publication status
- published
- subject
- keywords
- Växtgenetik, Plant genetics, pseudogenes, grasses, cytosolic PGI, introgression, duplication, Festuca ovina
- pages
- 102 pages
- publisher
- Lena Ghatnekar, Dept. of Cell and Organism Biology, Lund University, Sweden,
- defense location
- Genetics building, Sölvegatan 29, Lund
- defense date
- 2003-11-29 10:00:00
- ISBN
- 91-85067-07-5
- language
- English
- LU publication?
- yes
- additional info
- Article: BO Bengtsson, P Weibull and L Ghatnekar (1995) The loss of alleles by sampling: a study of the common outbreeding grass Festuca ovina over three geographic scales Hereditas 122: 221-238 Article: L Ghatnekar (1999) A polymorphic duplicated locus for cytosolic PGI segregating in sheep's fescue (Festuca ovina L.) Heredity 83: 451-459 Article: L Ghatnekar and BO Bengtsson (2000) A DNA marker for the duplicated cytosolic PGI genes in sheep's fescue (Festuca ovina L.) Genetical Research 76: 319-322 Article: L Ghatnekar, M Jaarola and BO Bengtsson (Manuscript) Molecular and evolutionary characterization of the extraneous PgiC locus in sheep's fescue (Festuca ovina L.)
- id
- f652a8ce-1d72-4f16-955c-68257e51674a (old id 466413)
- date added to LUP
- 2016-04-04 10:44:16
- date last changed
- 2018-11-21 21:00:31
@phdthesis{f652a8ce-1d72-4f16-955c-68257e51674a,
abstract = {{<i>Festuca ovina</i>, sheep's fescue is a widely distributed perennial outbreeder that belongs to the grass family Poaceae and is very common in the northern temperate zone. The genus <i>Festuca s.l.</i> is partitioned into fine-leaved fescues to which <i>F. ovina</i> belongs, and broad-leaved fescues to which the genus <i>Lolium</i> is a close relative. Wide crosses within the <i>Festuca-Lolium</i> complex often yield fertile hybrids. My thesis describes a genetic analysis of the variation for cytosolic phosphoglucose isomerase (PGI) in <i>Festuca ovina</i>. The investigation was initiated since an isozyme study demonstrated that some plants had multibanded electrophoretic patterns that proved genetically uninterpretable. Chromosome analysis showed that the plants were not polyploid, but diploid with the standard number of 14 chromosomes. Classical genetic analysis based on artificial crosses revealed that a second PGI locus segregated in south-Swedish populations of <i>F. ovina</i>. The second locus (<i>PgiC2</i>) and the standard locus (<i>PgiC1</i>) assorted independently, <i>i.e.</i> were not linked. Sequence data revealed that the two loci were highly diverged. Moreover, <i>PgiC2</i> proved to be more complex than <i>PgiC1</i>, since all three <i>PgiC2</i> variants analysed were composed of two genes. One of these genes may be a pseudogene. The results demonstrate that <i>PgiC2</i> is not a simple, duplicated version of <i>PgiC1</i>. The sequences present today at these two loci must have started to diverge a long time ago, perhaps as far back as the time of the differentiation of the genus. I suggest that <i>PgiC2</i> entered <i>F. ovina</i> recently via an introgression event from another species in the <i>Festuca-Lolium</i> complex, where it normally functions as the "standard" locus for cytosolic PGI. This model is supported by the fact that alleles from <i>PgiC1</i> and <i>PgiC2</i> produce enzyme subunits that easily function together despite their wide sequence divergence. Thus, my thesis brings into focus a possible but not much discussed way for eukaryot organisms to add new genes to their genomes.}},
author = {{Ghatnekar, Lena}},
isbn = {{91-85067-07-5}},
keywords = {{Växtgenetik; Plant genetics; pseudogenes; grasses; cytosolic PGI; introgression; duplication; Festuca ovina}},
language = {{eng}},
publisher = {{Lena Ghatnekar, Dept. of Cell and Organism Biology, Lund University, Sweden,}},
school = {{Lund University}},
title = {{Genetic Analysis of Cytosolic PGI in <i>Festuca ovina</i>}},
year = {{2003}},
}