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Elymus sibiricus L. is a perennial allotetraploid belonging to Triticeae of Poaceae, Elymus L., as the type species of genus Elymus L. The existing geographical distribution pattern and genetic spatial structure of E. sibiricus on Qinghai–Tibetan Plateau (QTP) are not yet clear. In this study, population genetic structure and demography history of 216 individuals from 44 E. sibiricus populations on QTP were studied used specific-locus amplified fragment sequencing (SLAF-seq). The result of genetic diversity showed that there was no single genetic diversity center was observed across all E. sibiricus populations. The results of genetic variation showed that 44 populations were clearly divided into the following three groups: Qinghai Plateau (Group I), South Tibet (Group II), and Hengduan Mountains (Group III). From the three analyses of AMOVA, Mantel test and Treemix, strong genetic differentiation across all populations and low genetic differentiation among populations within three groups. Molecular dating indicated that E. sibiricus diverged at 16.08 Ma (during the early Miocene) can be linked to the Himalayan Motion stage of QTP uplift. It is speculated that the reasons affecting the current phylogeographical pattern are as follows: (1) The environmental changes due to the uplift of the QTP; (2) The geographic distance between the populations (Groups I and III are close in geographic distance, and gene flow are frequent); (3) Geographical barriers (the Tanggula and Bayangela Mountains between Groups I and II). This study provides new evidence and historical perspective to the future exploration of the evolution and geographic distribution pattern of Elymus L. [ABSTRACT FROM AUTHOR]

The most intriguing characteristics of plant mitochondrial genomes (mitogenomes) include their high variation in both sequence and structure, the extensive horizontal gene transfer (HGT), and the important role they play in hypoxic adaptation. However, the investigation of the mechanisms of hypoxic adaptation and HGT in plant mitochondria remains challenging due to the limited number of sequenced mitogenomes and non-coding nature of the transferred DNA. In this study, the mitogenome of Elymus sibiricus (Gramineae, Triticeae), a perennial grass species native to the Qinghai-Tibet plateau (QTP), was de novo assembled and compared with the mitogenomes of eight Gramineae species. The unique haplotype composition and higher TE content compared to three other Triticeae species may be attributed to the long-term high-altitude plateau adaptability of E. sibiricus. We aimed to discover the connection between mitogenome simple sequence repeats (SSRs) (mt-SSRs) and HGT. Therefore, we predicted and annotated the mt-SSRs of E. sibiricus along with the sequencing of 87 seed plants. The clustering result based on all of the predicted compound mitogenome SSRs (mt-c-SSRs) revealed an expected synteny within systematic taxa and also inter-taxa. The mt-c-SSRs were annotated to 11 genes, among which "(ATA)3agtcaagtcaag (AAT)3" occurred in the nad5 gene of 8 species. The above-mentioned results further confirmed the HGT of mitogenomes sequences even among distant species from the aspect of mt-c-SSRs. Two genes, nad4 and nad7 , possessed a vast number of SSRs in their intron regions across the seed plant mitogenomes. Furthermore, five pairs of SSRs developed from the mitogenome of E. sibiricus could be considered as potential markers to distinguish between the species E. sibiricus and its related sympatric species E. nutans. [ABSTRACT FROM AUTHOR]

Phalaris arundinacea , with its characteristics of rapid growth and high biological yield, is regarded as an excellent forage grass in the Qinghai-Tibetan Plateau region of China. To explore the physiological and molecular response mechanism of Phalaris arundinacea under salt stress, we monitored the biomass and physiological indexes of two locally grown strains under conditions of exposure to 150 and 300 mM NaCl solution. Z0611 exhibited better salt stress tolerance than YS. Transcriptome sequencing analysis showed that YS and Z0611 had 1713 and 4290 differentially expressed genes (DEGs), respectively, including on metabolic processes, single-organism process, catalytic activity, and plant hormone signal transduction in the GO and KEGG databases. We also identified a large number of genes involved in hormone signaling, antioxidant systems, ion homeostasis, and photosynthetic systems. Our study provides physiological and molecular insight for establishing a salt resistance database and mining salt tolerance genes in Phalaris arundinacea , and also provides theoretical guidance for the restoration of saline-alkali land on the Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]