Genome size variation in Deschampsia cespitosa sensu lato (Poaceae) in Eurasia

Josef Greimler,Eva M Temsch,Zhiqing Xue,Hanna Weiss-Schneeweiss,Polina Volkova,Markus Peintinger,Pawel Wasowicz,Hui Shang,Ivan Schanzer,Jorge O Chiapella

doi:10.1007/s00606-021-01796-7

Abstract

The grass Deschampsia cespitosa is a variable taxon out of which many varieties, subspecies and endemic species have been separated. In this paper, the variation in genome size (GS) and ploidy of this grass including several of its subspecies and two related species in Eurasia was investigated by flow cytometric (FCM) measurements. GS and ploidy data were also related to specific environments and reproduction mode. Ploidy levels found by FCM were confirmed by chromosome counts of diploid (2n = 26) and tetraploid (2n = 52) samples. Seminiferous (seed bearing) D. cespitosa was mainly diploid (GS between 3.754 and 5.438 pg/1C). GS variation in diploids showed a geographic pattern with a significant difference (H = 41,441, P < 0.001) between European (median = 4.377 pg) and Asian (median = 4.881 pg) accessions. Genome size (1C) in tetraploids ranged from 7.9426 to 9.0399 pg. Tetraploid seminiferous D. cespitosa was found mostly in disturbed habitats in western and southern Europe, while tetraploids in Asia were registered in wet Arctic habitats. Genome size (1C between 8.3278 and 8.8603 pg) of the pseudoviviparous plants (spikelets produce plantlets asexually) of wet habitats in central and northern Europe indicated tetraploidy. A putative triploid (GS 6.6817 pg) was detected in Iceland. Summing up, we found a high variation in GS on the geographic scale with significant regional differences in diploid D. cespitosa. Among the tetraploids, the asexually reproducing plants were bound to specific habitats, while the seminiferous plants showed a habitat preference similar to the diploids.

Highlights

There is increasing evidence that all plant lineages have undergone several whole-genome doubling (WGD) events, i.e., cycles of polyploidization (e.g., Jiao et al 2011; Soltis et al 2014; Wendel et al 2018) the exact number and timing of these events are still disputed (Ruprecht et al 2017)
Using flow cytometry (FCM), this paper reports the genome size and ploidy-level variation of multiple populations of D. cespitosa to (i) identify biogeographic patterns related to genome size and ploidy levels; (ii) examine to which extent ploidy is related to specific environments and asexual reproduction
Plant leaves of 129 populations of Deschampsia cespitosa and two related species for FCM were collected in the field and dried under standard herbarium conditions

Summary

Introduction

There is increasing evidence that all plant lineages have undergone several whole-genome doubling (WGD) events, i.e., cycles of polyploidization (e.g., Jiao et al 2011; Soltis et al 2014; Wendel et al 2018) the exact number and timing of these events are still disputed (Ruprecht et al 2017). Deschampsia cespitosa is a tussockforming, wind-pollinated, self-incompatible grass, occurring in habitats with moderate to high moisture in a cold-temperate climate. This grass has established populations in similar habitats in regions separated by thousands of kilometers, where appropriate ecological conditions are present

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Conclusion