Phenotype- and SSR-Based Estimates of Genetic Variation between and within Two Important Elymus Species in Western and Northern China

Abstract

Elymus nutans and Elymus sibiricus are two important perennial forage grasses of the genus Elymus, widely distributed in high altitude regions of Western and Northern China, especially on the Qinghai-Tibetan Plateau. Information on phenotypic and genetic diversity is limited, but necessary for Elymus germplasm collection, conservation, and utilization. In the present study, the phenotypic and genetic differentiation of 73 accessions of the two species were evaluated using 15 phenotypic traits and 40 expressed sequence tag derived simple sequence repeat markers (EST-SSRs). The results showed that only 7.23% phenotypic differentiation (Pst) existed between the two Elymus species based on fifteen quantitative traits. Principal component analysis (PCA) revealed that leaf traits, spike traits, and some seed traits were dominant factors in phenotypic variation. Moreover, 396 (97.8%) and 331 (87.1%) polymorphic bands were generated from 40 EST-SSR primers, suggesting high levels of genetic diversity for the two species. The highest genetic diversity was found in the Northeastern Qinghai-Tibetan Plateau groups. Clustering analysis based on molecular data showed that most accessions of each Elymus species tended to group together. Similar results were described by principal coordinates analysis (PCoA) and structure analysis. The molecular variance analysis (AMOVA) revealed that 81.47% and 89.32% variation existed within the geographical groups for the two species, respectively. Pearson’s correlation analyses showed a strong positive correlation between Nei’s genetic diversity and annual mean temperature. These results could facilitate Elymus germplasm collection, conservation, and future breeding.

Genetic Divergence and Relationship Among Opisthopappus Species Identified by Development of EST-SSR Markers

“…Due to the lack of sufficient genetic information and effective molecular marker systems, the phylogenetic relationship between Opisthopappus (Asteraceae) species remains unclear and unresolved to a certain extent. SSR markers are considered to be one of the most important marker systems for plant genetic studies, with high polymorphisms, high abundance, co-dominance, and genome-wide distribution (Thakur and Randhawa, 2018;Zhang et al, 2018). Compared with the genomic SSRs, EST-SSRs are effective and useful markers for non-model plants, which are easily transferred between related species owing to these regions being more evolutionarily conserved than non-coding sequences (Varshney et al, 2005;Ellis and Burke, 2007;Tahan et al, 2009;Bazzo et al, 2018;Park et al, 2019).…”

Potential Effects of Awn Length Variation on Seed Yield and Components, Seed Dispersal and Germination Performance in Siberian Wildrye (Elymus sibiricus L.)

“…Seed samples were taken from the center of each plot to avoid border effects. Because of serious seed shattering reported in this species [1], seeds were harvested when the seed moisture content was approximately 45% [44]. Seeds of each plant were air-dried, carefully threshed, cleaned, weighed and stored in paper bags at 20 • C and 15% relative humidity before subjected to seed yield evaluation and other seed measurements.…”

“…Siberian Wildrye (Elymus sibiricus L.), which belongs to the genus Elymus (Poaceae: Triticeae), is an important perennial, self-pollinating and cool-season bunchgrass. The grass is native to the high altitude regions of western and northern China [1] and widespread in Asia, Europe and North America [2]. This species has erect naked stems with evenly distributed basal leaves, providing good grazing for livestock.…”

Why Self-fertilizing Plants Still Exist in Wild Populations: Diversity Assurance through Stress-Induced Male Sterility May Promote Selective Outcrossing and Recombination

“…Although these are wild selfing populations, studies have shown that within-population genetic diversity can be moderate and significant in some of them, and as such they are heterogeneous populations of near-homozygous individual plants. This has been documented in diverse wild populations of grasses, including wild oats in China and the USA [60], Elymus breviaristatus in China [61], Elymus nutans and Elymus sibiricus, important perennial forages, in China [62], Elymus tangutorum, a pasture bunchgrass, in China [63], wild emmer wheat (Triticum turgidum ssp. dicoccoides) in Israel [64], Thinopyrum junceum and Thinopyrum junceiforme in Spain [65], Paspalum dilatatum subsp.…”