Genome size variation in the genus Avena

Abstract

Abstract:Genome size is an indicator of evolutionary distance and a metric for genome characterization. Here, we report accurate estimates of genome size in 99 accessions from 26 species of Avena. We demonstrate that the average genome size of C genome diploid species (2C = 10.26 pg) is 15% larger than that of A genome species (2C = 8.95 pg), and that this difference likely accounts for a progression of size among tetraploid species, where AB < AC < CC (average 2C = 16.76, 18.60, and 21.78 pg, respectively). All accessions from three hexaploid species with the ACD genome configuration had similar genome sizes (average 2C = 25.74 pg). Genome size was mostly consistent within species and in general agreement with current information about evolutionary distance among species. Results also suggest that most of the polyploid species in Avena have experienced genome downsizing in relation to their diploid progenitors. Genome size measurements could provide additional quality control for species identification in germplasm collections, especially in cases where diploid and polyploid species have similar morphology.Key words: oat, flow cytometry, nucleus, polyploidy.Résumé : La taille du génome est un indicateur de la distance évolutive et constitue un paramètre pour la caractéri-sation des génomes. Ici, les auteurs rapportent des estimés précis de la taille du génome chez 99 accessions appartenant à 26 espèces du genre Avena. Les auteurs montrent que la taille moyenne du génome chez les espèces diploïdes ayant un génome C (2C = 10,26 pg) est 15 % supérieure à celui des espèces ayant un génome A (2C = 8,95 pg), et que cette différence explique vraisemblablement la progression dans la taille des génomes parmi les espèces tétraploïdes, où AB < AC < CC (en moyenne, 2C = 16,76, 18,60 et 21,78 pg, respectivement). Toutes les accessions des trois espèces hexaploïdes ayant une composition génomique ACD présentaient des tailles de génome comparables (en moyenne, 2C = 25,74 pg). La taille du génome était généralement stable au sein d'une espèce, et conforme aux connaissances actuelles en ce qui a trait aux distances évolutives entre elles. Les résultats suggèrent également que la plupart des espèces polyploïdes du genre Avena ont connu une réduction de la taille du génome par rapport aux espèces diploïdes ancestrales. Les mesures de la taille du génome pourraient fournir une source additionnelle de contrôle de qualité lors de l'identification des espèces au sein de collections de ressources génétiques, particulièrement dans les cas où des espèces diploïdes et polyploïdes présentent une morphologie semblable. [Traduit par la Rédaction] Mots-clés : avoine, cytométrie en flux, noyau, polyploïdie.

De novo transcriptome assembly, development of EST-SSR markers and population genetic analyses for the desert biomass willow, Salix psammophila

“…In Knautia , the results of ploidy and genome size of 23 species indicated that genome size of tetraploid K. arvernensis and hexaploid K. ressmannii is approximately 1.8-fold and approximately 2.7-fold than diploid K. calycina , respectively41. Similar results of the genome size being inconsistent with the ploidy level were also observed in Chenopodium 42 and Avena 43. One likely reason for this phenomenon is that some genes or chromosome fragments with functional redundancy had not doubled in a genome duplication event, or they were deleted after genome duplication event44.…”

A genetic linkage map in southern‐by‐spring oat identifies multiple quantitative trait loci for adaptation and rust resistance

“…Though less pronounced, this trend was also observed in the consensus map and each of its component maps (Chaffin et al., ). Indirect evidence (since no extant D genome diploid is known) suggests that the D genome has the smallest physical size of the component genomes in hexaploid or tetraploid oat (Yan et al., ). However, physical chromosome size does not necessarily correlate with recombination distance or even with the number of polymorphic markers.…”

“…Indirect evidence (since no extant D genome diploid is known) suggests that the D genome has the smallest physical size of the component genomes in hexaploid or tetraploid oat (Yan et al, 2016a).…”

“…Its grain is high in protein, soluble fibre and antioxidants, which makes it valuable in human nutrition. Oat has a large allohexaploid (2 n = 6 x = 42) genome with a haploid size of approximately 12.5 Gb (Yan et al., ). Oat germplasm is often characterized being either spring or winter type; however, there are two types of winter production areas: those where oats remain dormant over winter, and those that utilize a winter growing season, which are sometimes referred to as southern oat types.…”

Polyphyletic Alyssum cuneifolium (Brassicaceae) revisited: Morphological and genome size differentiation of recently recognized allopatric taxa

“…In plants, the monoploid genome size of polyploids is usually lower than that of their diploid or lower polyploid relatives due to a selective force or endogenous mechanisms favouring DNA loss after polyploidization (Leitch & Bennett, 2004;De Smet et al, 2013). The prevalent trend towards genome downsizing correlated with increasing ploidy level in polyploid series of closely related species (or within species) has been repeatedly confirmed in many plant genera, most recently, for example, in Aloe L. (Rao et al, 2015), Avena L. (Yan et al, 2016), Calligonum L. (Gouja et al, 2015), Chrysanthemum L. (Luo et al, 2017), Festuca L. (Ezquerro-L opez et al, 2017), Fragaria L. (Nosrati, 2015), Knautia L. , (Meudt et al, 2015). Considering this general trend, the opposite patterns observed in the Alyssum species under study could be attributed to the fact that they are not each others' closest relatives (Zozomov a-Lihov a et al, 2014;Spaniel et al, 2017a); however, there are also other possible explanations.…”