Project description:BackgroundElucidating the effects of geography and selection on genetic variation is critical for understanding the relative importance of adaptation in driving differentiation and identifying the environmental factors underlying its occurrence. Adaptive genetic variation is common in tree species, especially widely distributed long-lived species. Pseudotaxus chienii can occupy diverse habitats with environmental heterogeneity and thus provides an ideal material for investigating the process of population adaptive evolution. Here, we characterize genetic and expression variation patterns and investigate adaptive genetic variation in P. chienii populations.ResultsWe generated population transcriptome data and identified 13,545 single nucleotide polymorphisms (SNPs) in 5037 unigenes across 108 individuals from 10 populations. We observed lower nucleotide diversity (π = 0.000701) among the 10 populations than observed in other gymnosperms. Significant negative correlations between expression diversity and nucleotide diversity in eight populations suggest that when the species adapts to the surrounding environment, gene expression and nucleotide diversity have a reciprocal relationship. Genetic structure analyses indicated that each distribution region contains a distinct genetic group, with high genetic differentiation among them due to geographical isolation and local adaptation. We used FST outlier, redundancy analysis, and latent factor mixed model methods to detect molecular signatures of local adaptation. We identified 244 associations between 164 outlier SNPs and 17 environmental variables. The mean temperature of the coldest quarter, soil Fe and Cu contents, precipitation of the driest month, and altitude were identified as the most important determinants of adaptive genetic variation. Most candidate unigenes with outlier signatures were related to abiotic and biotic stress responses, and the monoterpenoid biosynthesis and ubiquitin-mediated proteolysis KEGG pathways were significantly enriched in certain populations and deserve further attention in other long-lived trees.ConclusionsDespite the strong population structure in P. chienii, genomic data revealed signatures of divergent selection associated with environmental variables. Our research provides SNPs, candidate unigenes, and biological pathways related to environmental variables to facilitate elucidation of the genetic variation in P. chienii in relation to environmental adaptation. Our study provides a promising tool for population genomic analyses and insights into the molecular basis of local adaptation.
| S-EPMC8157689 | biostudies-literature
Project description:Characterization of transcriptomes of Pseudotaxus chienii populations
Project description:Lindera chienii Cheng 1934 is an important medicine plant. The first complete plastid genome sequence of L. chienii was assembled and analyzed in this study. The plastid genome is 152,744 bp in length with a GC content of 39.15%, contains a large single-copy region of 93,767 bp and a small single-copy region of 18,843 bp, which were separated by a pair of inverted repeat regions of 20,067 bp. A total of 128 genes were detected in the plastid genome, including eight ribosomal RNA genes, 36 transfer RNA genes, and 81 protein-coding genes. The phylogenomic analysis based on plastid genomes supports the close relationships among Lindera chienii, L. megaphylla and Litsea acutivena.
Project description:Pseudotaxus chienii is an endangered coniferous plant that is endemic to China. Because P. chienii is sessile and has a long life cycle, its options for responding to drastic or rapid changes in climate are limited. To survive locally, P. chienii must be able to adapt, and the species shows variations in leaf size along an environmental gradient from east to west. It is important to determine whether this phenotypic variation is driven by DNA methylation. Therefore, we performed a preliminarily survey using methylation-dependent restriction-site associated DNA sequencing (MethylRAD) to investigate the methylation status of three P. chienii individuals from heterogeneous ecological niches. In total, 372,611 CCGG tags and 726,332 CCHGG tags were obtained. The rate of high quality methylation tags for a specific site in the genome varied from 42.31% (Gxdms3-4) to 50.01% (Jxbj3-4) and 50.18% (Zjdxg3-6). The level of CCHGG methylation (16.63%) was higher than that of CCGG (13.60%), which may be why P. chienii has low levels of phenotypic variation. The methylation data can be accessed using the Sequence Read Archive (SRA) database (SRP128155).