Journal Article

Genome size and base composition variation in natural and experimental <i>Narcissus</i> (Amaryllidaceae) hybrids

Isabel Marques, Gonzalo Nieto Feliner, Maria Amélia Martins-Loução and Javier Fuertes Aguilar

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 109, issue 1, pages 257-264
Published in print January 2012 | ISSN: 0305-7364
Published online November 2011 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcr282
Genome size and base composition variation in natural and experimental Narcissus (Amaryllidaceae) hybrids

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Although there is evidence that both allopolyploid and homoploid hybridization lead to rapid genomic changes, much less is known about hybrids from parents with different basic numbers without further chromosome doubling. Two natural hybrids, Narcissus × alentejanus (2n = 19) and N. × perezlarae (2n = 29), originated by one progenitor (N. cavanillesii, 2n = 28) and two others (N. serotinus, 2n = 10 and N. miniatus, 2n = 30, respectively) allow us to study how DNA content and composition varies in such hybrids.

Methods

Flow cytometry measurements with two staining techniques, PI and DAPI, were used to estimate 2C values and base composition (AT/GC ratio) in 390 samples from 54 wild populations of the two natural hybrids and their parental species. In addition, 20 synthetic F1 hybrid individuals were also studied for comparison.

Key Results

Natural hybrids presented 2C values intermediate between those found in their parental species, although intra-population variance was very high in both hybrids, particularly for PI. Genome size estimated from DAPI was higher in synthetic hybrids than in hybrids from natural populations. In addition, differences for PI 2C values were detected between synthetic reciprocal crosses, attributable to maternal effects, as well as between natural hybrids and those synthetic F1 hybrids in which N. cavanillesii acted as a mother.

Conclusions

Our results suggest that natural hybrid populations are composed of a mixture of markedly different hybrid genotypes produced either by structural chromosome changes, consistent with classic cytogenetic studies in Narcissus, or by transposon-mediated events.

Keywords: Amaryllidaceae; base composition; DAPI; flow cytometry; genome size; interspecific hybrids; Narcissus; polyploidy; propidium iodide

Journal Article.  5551 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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