Abstract
Cynodon dactylon (L.) Pers. (common Bermuda grass) has a limited capacity to grow at low temperatures, which limits its geographical range. Exploring its evolutionary relationship across different environmental gradients is necessary to understand the effects of temperature change on the genetics of common Bermuda grass. In this study, high-throughput transcriptome sequencing was performed on 137 samples of C. dactylon from 16 latitudinal gradients to explore the differential molecular markers and analyze genetic diversity and structure along latitudinal gradients at different temperatures. We primarily sampled more high-quality single nucleotide polymorphisms (SNPs) from populations at lower and middle latitudes. Greater intraspecific genetic variation at each level of temperature treatment could be due to factors such as wind pollination and asexual breeding. Populations of C. dactylon at high latitudes differed from populations at middle and low latitudes, which was supported by a principal component analysis (PCA) and genetic structure analysis, performed at different temperatures. We observed more genetic variation for low-latitude populations at 5 °C, according to an analysis of three phylogenetic trees at different temperature levels, suggesting that low temperatures affected samples with low cold resistance. Based on the results of phylogenetic analysis, we found that samples from high latitudes evolved earlier than most samples at low latitudes. The results provide a comprehensive understanding of the evolutionary phenomenon of landscape genetics, laying the groundwork for future structural and comparative genomic studies of C. dactylon.
Highlights
A major focus of evolutionary biology is understanding how genetic variation drives local adaptions across populations spanning wide geographical and environmental gradients
Greater intraspecific genetic variation, based on our analysis of molecular variance (AMOVA), could confer a competitive advantage in a changing environment. These results agree with the published results of our analysis of the genetic structure using expressed sequence tag-derived simple sequence repeats (EST-SSR) [29]
Our results indicate that phylogenetic clustering at high latitudes, along with the phylogenetic structure, tended to disperse individuals at low latitudes, due to favorable temperatures
Summary
A major focus of evolutionary biology is understanding how genetic variation drives local adaptions across populations spanning wide geographical and environmental gradients. Natural genetic differences related to the drought stress tolerance of plants, such as Festuca arundinacea Schreb and Lolium perenne L., have been studied [2,3]. Adaptations to this kind of stress have important implications for plant growth and adaptation to climate change [4,5]. C. dactylon is a warm-season turfgrass primarily ranging from latitudes of 45◦ N to 45◦ S. It is widely used for lawns, parks, and sports fields [6]. C. dactylon is an Plants 2020, 9, 1778; doi:10.3390/plants9121778 www.mdpi.com/journal/plants
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