Dracocephalum heterophyllum (Lamiaceae: tribe Mentheae) is an annual aromatic herb native to East Asia with a long record of human uses, including medicinal, alimentary, and ornamental values. However, no information is available about its molecular biology, and no genomic study has been performed on D. heterophyllum. Here, we report the complete chloroplast (cp) genome of D. heterophyllum and a series of comparative genomic analyses between this and closely related species of Lamiaceae. Results indicated that the cp genome has a typical circular structure of 150,869 bp in length, consisting of a long single-copy (LSC) region with 82,410 bp, a short single-copy (SSC) region with 17,098 bp, and two inverted repeat (IR) regions of 51,350 bp. A total of 133 genes were identified, including 37 tRNA genes, 8 rRNA genes and 88 protein-coding genes, with a GC content of 37.8%. The gene content, organization, and GC values observed here were similar to those of other Dracocephalum species. We detected 99 different simple sequence repeat loci, and the codon usage analysis revealed a preferential use of the Leu codon with an A/U ending. Comparative analysis of cp genome sequences revealed five highly variable regions with remarkably higher Pi values (>0.03). The mean Ka/Ks between D. heterophyllum and three other Dracocephalum species ranged from 0.01079 (psbB) to 1.0497 (ycf2). Two cp genes, ycf2 and rps11, were proven to have high ratios of Ka/Ks, implying that cp genes may had undergone positive selection in the evolutionary history. We performed multiple sequence alignments using the cp genome of 22 species and constructed maximum likelihood (ML) and Bayesian trees, and found that D. heterophyllum were more closely related to D. moldavica and D. palmatum. In addition, the phylogenetic relationships between Dracocephalum and other members of Lamiaceae were consistent with previous results. These results are valuable for further formulating effective strategies of conservation and management for species in Dracocephalum, as well as providing a foundation for future research on the genetic resources of Dracocephalum.

Psammochloa villosa is an ecologically important desert grass that occurs in the Inner Mongolian Plateau where it is frequently the dominant species and is involved in sand stabilization and wind breaking. We sought to generate a preliminary demographic framework for P. villosa to support the future studies of this species, its conservation, and sustainable utilization. To accomplish this, we characterized the genetic diversity and structure of 210 individuals from 43 natural populations of P. villosa using amplified fragment length polymorphism (AFLP) markers. We obtained 1,728 well‐defined amplified bands from eight pairs of primers, of which 1,654 bands (95.7%) were polymorphic. Results obtained from the AFLPs suggested effective alleles among populations of 1.32, a Nei's standard genetic distance value of 0.206, a Shannon index of 0.332, a coefficient of gene differentiation (G_ST) of 0.469, and a gene flow parameter (Nm) of 0.576. All these values indicate that there is abundant genetic diversity in P. villosa, but limited gene flow. An analysis of molecular variance (AMOVA) showed that genetic variation mainly exists within populations (64.2%), and we found that the most genetically similar populations were often not geographically adjacent. Thus, this suggests that the mechanisms of gene flow are surprisingly complex in this species and may occur over long distances. In addition, we predicted the distribution dynamics of P. villosa based on the spatial distribution modeling and found that its range has contracted continuously since the last interglacial period. We speculate that dry, cold climates have been critical in determining the geographic distribution of P. villosa during the Quaternary period. Our study provides new insights into the population genetics and evolutionary history of P. villosa in the Inner Mongolian Plateau and provides a resource that can be used to design in situ conservation actions and prioritize sustainable utilization.

Long noncoding RNAs (lncRNAs) are RNA molecules longer than 200 nt, which lack the ability to encode proteins and are involved in multifarious growth, development, and regulatory processes in plants and mammals. However, the environmental-regulated expression profiles of lncRNAs in Orinus that may associated with their adaptation on the Qinghai-Xizang (Tibet) Plateau (QTP) have never been characterized. Here, we utilized transcriptomic sequencing data of two Orinus species (O. thoroldii and O. kokonoricus) to identify 1624 lncRNAs, including 1119 intergenic lncRNAs, 200 antisense lncRNAs, five intronic lncRNAs, and 300 sense lncRNAs. In addition, the evolutionary relationships of Orinus lncRNAs showed limited sequence conservation among 39 species, which implied that Orinus-specific lncRNAs contribute to speciation adaptation evolution. Furthermore, considering the cis-regulation mechanism, from 286 differentially expressed lncRNAs (DElncRNAs) and their nearby protein coding genes (PCGs) between O. thoroldii and O. kokonoricus, 128 lncRNA-PCG pairs were obtained in O. thoroldii, whereas 92 lncRNA-PCG pairs were obtained in O. kokonoricus. In addition, a total of 19 lncRNA-PCG pairs in O. thoroldii and 14 lncRNA-PCG pairs in O. kokonoricus were found to participate in different biological processes, indicating that the different expression profiles of DElncRNAs between O. thoroldii and O. kokonoricus were associated with their adaptation at different elevations on the QTP. We also found several pairs of DElncRNA nearby transcription factors (TFs), indicating that these DElncRNAs regulate the expression of TFs to aid O. thoroldii in adapting to the environment. Therefore, this work systematically identified a series of lncRNAs in Orinus, laying the groundwork for further exploration into the biological function of Orinus in environmental adaptation.