Variation in ploidy level and genome size of Cynodon dactylon (L.) Pers. along a latitudinal gradient

Abstract

Knowledge of ploidy level and genome size in a germplasm collection is critical before studying genetic diversification of different environmental range in grasses and other plants. We assessed the geographic patterns in ploidy level and genome size of 216 individuals of Cynodon dactylon (L.) Pers. (common bermudagrass) by flow cytometry of accessions sampled from 16 geographic sites along a latitudinal gradient from 22°35′ N to 36°18′ N across China. Flow cytometry histograms combined with mitotic chromosome observations results show that tetraploids were the most frequent ploidy level, constituting 44.91% of all individuals. Nuclear DNA contents were 2.384, 2.419, 2.437, 2.873 and 3.288 pg/2C for the diploid, triploid, tetraploid, pentaploid and hexaploid, respectively. Higher proportions of polyploid individuals were observed within populations at the highest and lowest latitudes. In addition, monoploid genome size of C. dactylon progressively increased with increasing ploidy level. Temperature and precipitation had the influence on ploidy level for all the sites. The relationship between ploidy level and geographic distribution for C. dactylon will facilitate the utilization of this species for biological and genetic research.

Genetic Diversity and Population Structure of Bermudagrass [Cynodon dactylon (L.) Pers.] along Latitudinal Gradients and the Relationship with Polyploidy Level

“…From these facts above, polyploidization as well as increased genetic diversity may be the genetic mechanisms for the wide-spreading ability while genetic diversity contributes to the ability to respond to different environments. C. dactylon individuals with higher ploidy level showed larger morphological size suitable for forage production, in contrast, those with lower ploidy level had smaller size for turfgrass utilization [51]. Therefore, from the result, polyploidy could be a very efficient tool in forage and turf grass breeding of C. dactylon.…”

Genome-wide analysis tracks the emergence of intraspecific polyploids inPhragmites australis

“…USland showed exceptionally high divergence with Neoploid (Fst = 0.44689), but moderate divergence with AU, EU, CN and Med (0.29 < Fst< 0.35, Table 8). The lowest Fst value was observed between Neoploid (South Africa) and EU lineages (0.17126), suggesting recent gene flow (Table 5, 8). We therefore analysed the geneflow using formal tests of introgression.…”

“…Depending on their lineages, the current diploids have experienced further WGDs in the form of allo-or autopolyploidization, giving rise to the current grass species.A recent polyploidization event can be directly inferred when closely related species show different chromosome counts or genome sizes, which differ by an integer-valued factor. This can often be observed in species within the same genus, but in some cases different ploidy levels have been observed also within the same species, such as Dupontia fisheri, Betula pendula, Lygeum spartum, Cynodon dactylon and Phragmites australis [5][6][7][8][9] . These species are thus ideal models to understand the factors that drive polyploidization.…”

Sympatric genome size variation and hybridization of four oak species as determined by flow cytometry genome size variation and hybridization

“…Polyploidization events and transposable element (TE) amplification in plants lead to genome expansion (Hawkins et al., 2008; Kumar & Bennetzen, 1999; Wood et al., 2009), while recombination processes may lead to genome contraction (Devos et al., 2002; Hawkins et al., 2009; Schubert & Vu, 2016). Natural selection exerts a force on the genome; consequently, GS variation is usually related to the living environment, including the altitude, latitude, temperature, and precipitation level (Bennett et al., 2000; Hidalgo et al., 2015; Knight & Ackerly, 2002; Knight et al., 2005; Li et al., 2017; Zhang et al., 2019). GS allows the detection of interspecific hybrids and/or backcrosses (Vit et al, 2014; Yan et al., 2016) and has been widely applied to various plants, such as Sarcococca (Denaeghel et al., 2017; Prancl et al., 2014; Tlili et al., 2020).…”

“…Flow cytometry (FCM), which is a fast and effective tool to estimate GS, has been successfully applied to ploidy identification, cell cycle analysis, and species identification, including hybrids, rarely occurring cytotypes, and aneuploids (Francis et al., 2008; Hanusova et al., 2014; Vit et al., 2014; Zhang et al., 2019). It has been used successfully in plant genetic variation studies, genetic analyses, and breeding, as well as in studies of reproductive ecology, evolution, and plant system classification (Bilinski et al., 2018; Galbraith, 2004; Sharma et al, 2019; Spaniel et al., 2019).…”