G.I.R.O.S. - Gruppo Italiano per la Ricerca sulle Orchidee Spontanee

Solo il fiore che lasci sulla pianta è tuo. (Aldo Capitini)
Oggi è 29 marzo 2024, 16:49

Tutti gli orari sono UTC +1 ora [ ora legale ]




Apri un nuovo argomento Rispondi all’argomento  [ 2 messaggi ] 
Autore Messaggio
MessaggioInviato: 19 novembre 2012, 11:19 
Non connesso
Amministratore
Avatar utente

Iscritto il: 29 maggio 2011, 16:05
Messaggi: 1646
Nome: Luca
Cognome: Oddone
Località: Mongardino (AT)
Tratto da: Botany 2012 - Columbus, Ohio, U.S.A. - 7 -11 luglio 2012


Abstract Detail

Epigenetics and allotetraploids in Dactylorhiza (Orchidaceae).

Hybridization and polyploidy are potent forces that have regularly stimulated plant evolution and adaptation. Dactylorhiza majalis s.s., D. traunsteineri s.l. and D. ebudensis are three allopolyploid species of a polyploid complex formed through unidirectional hybridization between the widespread diploids D.fuchsii and D. incarnata. Differing considerably in geographical extent and ecological tolerance, the three allopolyploids together provide a useful system to explore genomic responses to allopolyploidization and reveal their role in adaptation to contrasting environments. Analyses of gene expression show a significant increase in number of gene variants expressed in the allopolyploid lineages (including novel alleles), providing clear evidence of increased biological complexity following allopolyploidization. The epigenetic variation released by genome doubling has been restructured in species-specific patterns that reflect their recent evolutionary history and have an impact on their ecology and evolution, hundreds of generations after their formation. The stable epigenetic divergence between the allopolyploids is largely responsible for persistent ecological differences, which then set the stage for species-specific genetic patterns to accumulate in response to further selection and/or drift. Using NGS technologies, we are currently comparing mRNA expression levels between the allopolyploids and their parents. During this investigation we have been constructing reference transcriptomes for the two diploid parents, which contribute important genomic resources for Orchidaceae in general. In addition to stabilizing the allopolyploid genome, genetic and epigenetic alterations are key determinants of adaptive success of the new polyploid species after recurrent allopolyploidization events, potentially triggering reproductive isolation between the resulting lineages.

Allegato:
Hybrid origin of Dactylohirza majalis s.s., D. traunsteineri e D. ebudensis.PNG
Hybrid origin of Dactylohirza majalis s.s., D. traunsteineri e D. ebudensis.PNG [ 37.33 KiB | Osservato 6629 volte ]


1 - Royal Botanic Gardens - Kew, Jodrell Laboratory, Kew Road, Richmond, N/A, TW9 3DS, United Kingdom
2 - University Of Vienna, Department For Systematic And Evolutionary Botany, Rennweg 14, Vienna, Austria, A-1030, United Kingdom

Keywords: epigenetics, Polyploidy, hybridization, local adaptation, Orchidaceae.

Presentation Type: Symposium or Colloquium Presentation
Session: C6
Location: Franklin B/Hyatt
Date: Wednesday, July 11th, 2012
Time: 4:15 PM
Number: C6011
Abstract ID:432


Top
 Profilo  
 
MessaggioInviato: 19 novembre 2012, 11:20 
Non connesso
Amministratore
Avatar utente

Iscritto il: 29 maggio 2011, 16:05
Messaggi: 1646
Nome: Luca
Cognome: Oddone
Località: Mongardino (AT)
Articolo disponibile in PDF:

Ovidiu Paun, Richard M Bateman, Michael F Fay, Javier A Luna, Justin Moat, Mikael Hedrén and Mark W Chase, 2011 - Altered gene expression and ecological divergence in sibling allopolyploids of Dactylorhiza (Orchidaceae). BMC Evolutionary Biology, 11:113



Abstract

Background: Hybridization and polyploidy are potent forces that have regularly stimulated plant evolution and adaptation. Dactylorhiza majalis s.s., D. traunsteineri s.l. and D. ebudensis are three allopolyploid species of a polyploid complex formed through unidirectional (and, in the first two cases, recurrent) hybridization between the widespread diploids D. fuchsii and D. incarnata. Differing considerably in geographical extent and ecological tolerance, the three allopolyploids together provide a useful system to explore genomic responses to allopolyploidization and reveal their role in adaptation to contrasting environments.

Results: Analyses of cDNA-AFLPs show a significant increase in the range of gene expression of these allopolyploid lineages, demonstrating higher potential for phenotypic plasticity than is shown by either parent. Moreover, allopolyploid individuals express significantly more gene variants (including novel alleles) than their parents, providing clear evidence of increased biological complexity following allopolyploidization. More genetic mutations seem to have accumulated in the older D. majalis compared with the younger D. traunsteineri since their respective formation.

Conclusions: Multiple origins of the polyploids contribute to differential patterns of gene expression with a distinct geographic structure. However, several transcripts conserved within each allopolyploid taxon differ between taxa, indicating that habitat preferences shape similar expression patterns in these independently formed tetraploids. Statistical signals separate several transcripts - some of them novel in allopolyploids - that appear correlated with adaptive traits and seem to play a role favouring the persistence of individuals in their native environments. In addition to stabilizing the allopolyploid genome, genetic and epigenetic alterations are key determinants of adaptive success of the new polyploid species after recurrent allopolyploidization events, potentially triggering reproductive isolation between the resulting lineages.



_____________________________________________________________________________________________________________

MARK CHASE. Chromosome number and polyploidy in angiosperms


_________________
:ciaoo:
Luca

«Nomina si nescis, perit et cognito rerum» - Se si ignora il nome delle cose, se ne perde anche la conoscenza. C. Linnaeus, Philosophia botanica (1751)

«I was much struck how entirely vague and arbitrary is the distinction between species and varieties. Charles Darwin, On the Origin of Species (1859)

«This disagreement regarding bee orchid diversity represents a particularly extreme example of a phenomenon that frequently afflicts taxonomy - a dichotomy between researchers who divide natural variation into as many units as possible (splitters) and others who aggregate those subtly different units into entities that they consider to be either more easily recognised or more biologically meaningful (lumpers)» - R.M. Bateman

«Un fiore, anche il più insignificante, è la mirabile risultanza di un collaudato progetto genomico, di precisi equilibri ecologici, dell'azione congiunta del sole, del terreno, della pioggia e della rugiada, del vento e degli insetti impollinatori. Quale unica specie consapevole della complessità di questi processi e della preziosità del risultante dono, è nostro dovere promuoverne la conoscenza e prodigarci per la sua protezione» - G. Sciarretta


Immagine

Nomenclatura GIROS - Biodiversity Heritage Library - IPNI, International Plant Names Index - Kew Gardens Checklist



Top
 Profilo  
 
Visualizza ultimi messaggi:  Ordina per  
Apri un nuovo argomento Rispondi all’argomento  [ 2 messaggi ] 

Tutti gli orari sono UTC +1 ora [ ora legale ]


Chi c’è in linea

Visitano il forum: Nessuno e 2 ospiti


Non puoi aprire nuovi argomenti
Non puoi rispondere negli argomenti
Non puoi modificare i tuoi messaggi
Non puoi cancellare i tuoi messaggi
Non puoi inviare allegati

Cerca per:
Vai a:  
cron
POWERED_BY
Traduzione Italiana phpBB.it