The fatty acid elongase 1 (FAE1) gene catalyzes the initial condensation step in the elongation pathway of VLCFA (very long chain fatty acid) biosynthesis and is thus a key gene in erucic acid biosynthesis. Based on a worldwide collection of 62 accessions representing 14 tribes, 31 genera, 51 species, 4 subspecies and 7 varieties, we conducted a phylogenetic reconstruction and correlation analysis between genetic variations in the FAE1 gene and the erucic acid trait, attempting to gain insight into the evolutionary patterns and the correlations between genetic variations in FAE1 and trait variations. The five clear, deeply diverged clades detected in the phylogenetic reconstruction are largely congruent with a previous multiple gene-derived phylogeny. The Ka/Ks ratio (<1) and overall low level of nucleotide diversity in the FAE1 gene suggest that purifying selection is the major evolutionary force acting on this gene. Sequence variations in FAE1 show a strong correlation with the content of erucic acid in seeds, suggesting a causal link between the two. Furthermore, we detected 16 mutations that were fixed between the low and high phenotypes of the FAE1 gene, which constitute candidate active sites in this gene for altering the content of erucic acid in seeds. Our findings begin to shed light on the evolutionary pattern of this important gene and represent the first step in elucidating how the sequence variations impact the production of erucic acid in plants.

Background: Apocynum venetum L. is an important medicinal plant that is mainly distributed in the coastal areas and northwest of China. In addition to its high medical and economic value, its adaptation to saline-alkali and coastal saline lands makes A. venetum an ideal candidate for use in vegetation restoration. To date, the study of A. venetum has been limited in the northwest region of China, little attention has been paid to the genetic diversity and population structure of A. venetum populations in the coastal region. Here, we performed transcriptome sequencing of total RNA from A. venetum leaves and developed efficient expressed sequence tag-simple sequence repeat (EST-SSR) markers for analyzing the genetic diversity and population structure of A. venetum in the coastal region. Results: A total of 86,890 unigenes were generated after de novo assembly, and 68,751 of which were successfully annotated by searching against seven protein databases. Furthermore, 14,072 EST-SSR loci were detected and 10,243 primer pairs were successfully designed from these loci. One hundred primer pairs were randomly selected and synthesized, twelve primer pairs were identified as highly polymorphic and further used for population genetic analysis. Population genetic analyses showed that A. venetum exhibited low level of genetic diversity (mean alleles per locus, N_A = 3.3; mean expected heterozygosity, H_E = 0.342) and moderate level of genetic differentiation among the populations (genetic differentiation index, F_ST = 0.032–0.220) in the coastal region. Although the contemporary (mean m_c = 0.056) and historical (mean m_h = 0.106) migration rates among the six A. venetum populations were moderate, a decreasing trend over the last few generations was detected. Bayesian structure analysis clustered six populations into two major groups, and genetic bottlenecks were found to have occurred in two populations (QG, BH). Conclusions: Using novel EST-SSR markers, we evaluated the genetic variation of A. venetum in the coastal region and determined conservation priorities based on these findings. The large dataset of unigenes and SSRs identified in our study, combining samples from a broader range, will support further research on the conservation and evolution of this important coastal plant and its related species.

Abies beshanzuensis, an endemic fir native to the subtropical high mountains of eastern China, is classified as a first-class nationally protected wild plant and is listed as Critically Endangered (CR) by the International Union for Conservation of Nature (IUCN). Taxonomic controversies have long persisted among A. beshanzuensis, A. ziyuanensis, and A. dayuanensis, yet studies focusing on their mitochondrial DNA remain limited. In this study, the complete mitochondrial genome of A. beshanzuensis was assembled using a combination of Oxford Nanopore long-read sequencing and Illumina short-read sequencing technologies. The mitochondrial genome is 1.06 Mb in size with a GC content of 45.97%, and consists of nine linear chromosomes and one circular chromosome. Comprehensive analyses, including genome annotation, structural comparisons, RNA editing site prediction, and phylogenetic reconstruction, were subsequently conducted. The results provide important insights into the mitochondrial genome architecture of A. beshanzuensis, offering a valuable resource for clarifying its controversial taxonomic status and advancing the understanding of evolutionary relationships within the genus Abies.

Peucedanum praeruptorum is an important traditional herbal medicine unique to China. The complete chloroplast genome of P. praeruptorum was generated here using high-throughput sequencing. The plastome was 147,197 bp in size, which consisted of a pair of inverted repeats (IRs; 18,713 bp), a large single copy (LSC; 92,161 bp) and a small single copy (SSC; 17,610 bp). The GC content of the plastome was 37.6%, with 44.5%, 36.0%, and 31.1% in IRs, LSC, and SSC, respectively. A total of 128 genes were annotated, including 84 protein-coding genes, 35 tRNAs, eight rRNAs, and one pseudogene (Ψycf1). The phylogenomic analysis indicated that P. praeruptorum formed a monophyletic clade with Peucedanum japonicum.

Zelkova schneideriana (Ulmaceae), an endemic relict species of the Tertiary in China, has experienced a sharp decline in population due to habitat fragmentation, poor natural regeneration, and anthropogenic disturbances. It is currently listed as a category II national key protected wild plant and categorized as Vulnerable by the International Union for Conservation of Nature (IUCN). To explore its response mechanisms to climate change, this study integrates 11 species distribution models (SDMs) to comprehensively predict its suitable habitat distribution patterns. Key environmental variables were identified as Bio06 (minimum temperature of the coldest month, 21.57%), Bio02 (mean diurnal range, 19.81%), Bio17 (precipitation of the driest quarter, 13.52%), Bio15 (precipitation seasonality, 8.32%), Bio07 (temperature annual range, 8.15%), Bio12 (annual precipitation, 6.58%), and elevation (6.57%), collectively contributing approximately 85%. Spatiotemporal analysis revealed that during historical glacial periods, suitable habitats were significantly restricted, and highly suitable zones were absent under extreme climatic conditions, suggesting the presence of potential glacial refugia. Under current climatic conditions, highly suitable habitats have expanded notably. However, under the high-emission scenario (SSP585) in the future, the suitable range is projected to shrink considerably, with a drastic reduction in highly suitable areas. Moreover, the suitability centroid is expected to shift markedly toward higher elevations in the northeast, indicating a potential adaptation strategy of Z. schneideriana toward mountainous regions in Hunan, Hubei, and Chongqing. These findings provide quantitative guidance for the formulation of targeted conservation strategies for Z. schneideriana and offer methodological insights for predicting suitable habitats and managing related relict plant species under the threat of climate change.

Glehnia littoralis is an important medicinal herb disjunctly distributed at sandy beaches in eastern Asia and western North America. The complete chloroplast genome sequence of G. littoralis is 147,552 bp in length and structurally divided into four distinct regions: two copies of inverted repeat of 18,365 bp separated by a large single copy (LSC) of 93,277 bp and a small single copy (SSC) of 17,545 bp. A total of 129 genes are annotated including 85 protein-coding genes, 36 tRNA gene, and eight rRNA genes. Phylogenetic relationship revealed that G. littoralis is closely related to Angelica dahurica in Apiaceae.