Kobresia species are common in meadows on the Qinghai–Tibet Plateau. They are important food resources for local livestock, and serve as a critical foundation for ecosystem integration. Genetic resources of Kobresia species are scarce. Here, we generated a chromosome-level genome assembly for K.myosuroides (Cyperaceae), using PacBio long-reads, Illumina short-reads, and Hi-C technology. The final assembly had a total size of 399.9Mb with a contig N50 value of 11.9 Mb. The Hi-C result supported a 29 pseudomolecules model which was in consistent with cytological results. A total of 185.5 Mb (44.89% of the genome) transposable elements were detected, and 26,748 protein-coding genes were predicted. Comparative analysis revealed that Kobresia plants have experienced recent diversification events during the late Miocene to Pliocene. Karyotypes analysis indicated that the fission and fusion of chromosomes have been a major driver of speciation, which complied with the lack of whole-genome duplication (WGD) in K. myosuroides genome. Generally, this high-quality reference genome provides insights into the evolution of alpine sedges, and may be helpful to endemic forage improvement and alpine ecosystem preservation.

BackgroundStudying population genetic structure and gene flow of plant populations and their influence factors is crucial in field of conservation biology, especially rare and endangered plants. Tetraena mongolica Maxim (TM), belong to Zygophyllaceae family, a rare and endangered plant with narrow distribution. Due to excessive logging, urban expansion, industrial development and development of the scenic spot in the last decades, has caused habitat fragments and decline.ResultsIn this study, the genetic diversity, the population genetic structure and gene flow of TM populations were evaluated by reduced representation sequencing technology, a total of more than 133.45 GB high-quality clean reads and 38,097 high-quality SNPs were generated. Analysis based on multiple methods, we found existing TM populations have moderate levels of genetic diversity, very low genetic differentiation and high levels of gene flow between populations. Population structure and principal coordinates analysis showed that 8 TM populations can be divided into two groups, Mantel test detected no significant correlation between geographical distances and genetic distance for the whole sampling. The migration model indicated that the gene flow is more of an north to south migration pattern in history.ConclusionsOur study demonstrate that the present genetic structure is mainly due to habitat fragmentation caused by urban sprawl, industrial development and coal mining. For recommendations of conservation management, all 8 populations should be protected as a whole population, rather than just those in the core area of TM nature reserve, especially the populations near the edge of TM distribution in cities and industrial areas deserve our special protection.

Background: Studying population genetic structure and gene flow of plant populations and their influencing factors is of particular significance in the field of conservation biology, especially important for species such as rare and endangered plants. Tetraena mongolica Maxim (TM), belongs to Zygophyllaceae family, a rare and endangered plant with narrow distribution. However, for the last decade, due to excessive logging, urban expansion, industrial and tourism development, habitat fragmentation and loss of natural habitats have become major threats to the population of endangered plants. Results: In this study, genetic diversity, population genetic structure and gene flow of TM populations were evaluated by reduced representation sequencing technology, and a total of more than 133.45 GB high-quality clean reads and 38,097 high-quality SNPs were generated. Analysis based on multiple methods, we found that the existing TM populations have moderate levels of genetic diversity , and very low genetic differentiation as well as high levels of gene flow between populations. Population structure and principal coordinates analysis showed that 8 TM populations can be divided into two groups. The Mantel test detected no significant correlation between geographical distances and genetic distance for the whole sampling. Moreover, the migration model indicated that the gene flow is more of an north to south migration pattern in history. Conclusions: This study demonstrates that the present genetic structure is mainly due to habitat fragmentation caused by urban sprawl, industrial development and coal mining. Our recommendation with respect to conservation management is that, all 8 populations should be preserved as a whole population, rather than just those in the core area of TM nature reserve, In particular, the populations near the edge of TM distribution in cities and industrial areas deserve our special protection.

Bolboschoenus planiculmis is a typical wetland sedge with both ecological and agricultural value. We report the first complete chloroplast genome sequence of this species. The total genome size is 186,539 bp, containing a large single-copy region (LSC) of 104,654 bp, a small single copy region (SSC) of 9,659 bp and two inverted repeats (IRs) of 36,113 bp by each. The GC content is 33.59%. The genome encodes 105 unique genes, including 71 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. Phylogenetic analysis shows this species has a strong sister relationship with Cyperus . Our work could be helpful in understanding the evolution of Cyperaceae.