Autori: Paun O, Luna JA, Fay MF, Bateman RM, Chase MW

Editorial: Seberg O, Petersen G, Barfod AS, Davis JI, Århus University Press, Denmark, Diversity, Phylogeny, and Evolution in the Monocotyledons, p.169-192, 2010.

Rezumat:

Hybridization and polyploidy are potent forces that have regularly stimulated plant evolution and speciation. Dactylorhiza majalis s.s., D. traunsteineri s.l. and D. ebudensis are three of several allopolyploid species formed independently through recurrent hybridization between the widespread diploids D. fuchsii and D. incarnata. Differing radically in geographical extent and ecological tolerance, the three allopolyploids provide a useful system to both uncover genomic responses to allopolyploidization and reveal the genetic/epigenetic basis of adaptation to divergent environments. Analyses of cDNA-AFLPs and methylation sensitive AFLPs (MSAP) show, respectively, a significant increase in the range
of gene expression and methylation variation of these allopolyploid lineages, demonstrating a higher (epi)genetic potential for phenotypic plasticity as compared to either parent. Moreover, allopolyploid individuals express significantly more gene variants (including novel ones) than the parents, providing clear evidence for an increase in biological complexity. Significantly fewer non-additive methylation patterns, but more genetic (physical) mutations, have accumulated in the older D. majalis compared with the younger D. traunsteineri since their respective formations. Multiple origins of each tetraploid taxon contribute to differential patterns of gene expression with a geographic structure. However, several transcripts and epimutations are conserved within each allopolyploid taxon but differ between taxa, indicating that habitat preferences shape similar expression patterns in independently formed allopolyploids. Statistical signals separate seven novel transcripts that may play a role favouring the presence of an individual in its native environmental landscape. In addition to stabilizing the allopolyploid genome, genetic and epigenetic alterations are key determinants of the adaptive success of the new allopolyploid species, potentially resulting in reproductive isolation.

Cuvinte cheie: polyploidy, hybridization, adaptation, genomics, epigenetics, gene expression