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Polyploidy, aneuploidy and change in DNA content of monoploid genomes or chromosomes are the principal causes of the variation in genome size. We studied these phenomena in central-European populations of the Valeriana officinalis complex in order to identify mechanisms or forces driving its evolution. The complex comprises di-, tetra-and octoploid morphologically defined so-called taxonomic "types". Within the study area there are also intermediate "transitional types" the existence of which hampers the application of traditional taxonomic concepts. We thus chose AFLP genotyping and admixture analyses to identify the genetic structuring of the material studied. Di-(2x), tetra-(4x) and octoploidy (8x) were confirmed as major ploidy levels. Major genetic clusters roughly corresponded to these ploidy levels (for K = 2: 2x-and 8x-clusters, for K = 4 with nearly identical probability: 2x-, 4x-, 8x-and unspecific clusters were identified), which further more significantly differed from each other in monoploid absolute genome size (mean 1Cx for 2x = 1.48 pg, 4x 1.29 pg, 8x 1.10 pg). Several individuals of all ploidy levels were admixed, particularly tetraploids. Relative genome size (the sample: standard DAPI fluorescence) was positively correlated with the proportion of the diploid genetic cluster shared by the tetraploids, indicating that hybridization caused the variation in genome size. This result is in accordance with the significant negative correlation of the genome size of tetraploids with their geographic distance to the diploids. However, remarkable intra-ploidy variation in relative genome size was recorded for all ploidy levels (1.14-fold in diploids, 1.28-fold in tetraploids, 1.19-fold in octoploids). We identified aneuploidy as an additional source of variation in genome size in the di-and tetraploids. The contribution of extra chromosomes to absolute genome size exceeded the observed variation within euploids in the diploids, whereas it was included in the regular variability in genome size recorded for the eutetraploids. Variation in monoploid genome size was recorded in polyploids but not in diploids, indicating that polyploids experienced higher dynamics in the evolution of their genomes. Finally, 38.0-63.2% of the total intra-ploidy variation in relative genome size occurred within populations. In conclusion, the Valeriana officinalis complex provides an example of variation in genome size due to four principal evolutionary forces: polyploidization, change in chromosome number and in DNA content of chromosomes and (secondarily) hybridization, but their relative importance differed among ploidy levels. Although the stability in the size of the monoploid genome in species is considered to be the standard case, we found great variability within populations suggesting that genome size is variable even within narrowly defined taxa.

(Acetoxy-)valerenic acid and total essential oil content are important quality attributes of pharmacy grade valerian root (Valerianae radix). Traditional analysis of these quantities is time-consuming and necessitates (harmful) solvents. Here we investigated an application of attenuated total reflection Fourier transform infrared spectroscopy for extractionless analysis of these quality attributes on a representative sample comprising 260 wild-crafted individuals covering the Central European taxonomic diversity of the L. s. l. species aggregate with its three major ploidy cytotypes (i.e., di-, tetra- and octoploid). Calibration models were built by orthogonal partial least squares regression for quantitative analysis of (acetoxy-)valerenic acid and total essential oil content. For the latter, we propose a simplistic protocol involving apolar extraction followed by gas chromatography as a reference method for multivariate calibration in order to handle the analysis of samples taken from individual plants. We found good predictive ability of chemometric models for quantification of valerenic acid, acetoxyvalerenic acid, total sesquiterpenoid acid, and essential oil content with a root mean squared error of cross-validation of 0.064, 0.043, and 0.09 and root mean squared error of prediction of 0.066, 0.057, and 0.09 (% content), respectively. Orthogonal partial least squares discriminant analysis revealed good discriminability between the most productive phenotype (i.e., the octoploid cytotype) in terms of sesquiterpenoid acids, and the less productive ones (i.e., di- and tetraploid). All in all, our results demonstrate the application of attenuated total reflection Fourier transform infrared spectroscopy for rapid, extractionless estimation of the most important quality attributes of valerian root and minimally invasive identification of the most productive phenotype in terms of sesquiterpenoid acids.

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