A genome size and phylogenetic survey of Mediterranean Tripleurospermum and Matricaria (Anthemideae, Asteraceae).

PLoS One. 2018 Oct 9;13(10):e0203762. doi: 10.1371/journal.pone.0203762. eCollection 2018. Inceer H1, Garnatje T2, Hayırlıoğlu-Ayaz S1, Pascual-Díaz JP2, Vallès J3, Garcia S2. Author information 1 Karadeniz Technical University, Faculty of Science, Department of Biology, Trabzon, Turkey. 2 Institut Botànic de Barcelona (IBB, CSIC-ICUB), Passeig del Migdia s/n, Parc de Montjuïc, Barcelona, Catalonia, Spain. 3 Laboratori de Botànica (UB)-Unitat associada al CSIC, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Catalonia, Spain. Abstract The study of genome size variation can contribute valuable information on species relationships as well as correlate to several morphological or ecological features, among others. Here we provide an extensive report on genome sizes on genus Tripleurospermum and its closely related genus Matricaria, which are two typically Mediterranean genera particularly widespread and diverse in Turkey, the origin of most of the populations here studied. We analyse and discuss genome size variation in the first relatively complete molecular phylogenetic framework of Tripleurospermum (based on ITS and ETS ribosomal DNA-rDNA-regions). We find cases of intraspecific genome size variation, which could be taxonomically significant. Genome downsizing is also detected as the typical response to polyploidisation in Tripleurospermum taxa, being most conspicuous at the tetraploid level. Several positive correlations with genome size, including those with pollen and stomatal size or cypsela length, among others, are also found. Remarkably, taxa presenting rhizomes tend to present higher genome sizes, confirming a trend to accumulate nuclear DNA in such species, which could be explained by the nutrient reserves availability in their storage organs, allowing genome expansion, or by the lower rates of sexual reproduction in rhizomatous taxa.