Stem cell-based tissue engineering provides a prospective strategy to bone tissue repair. Bone tissue repair begins at the recruitment and directional movement of stem cells, and ultimately achieved on the directional differentiation of stem cells. The migration and differentiation of stem cells are regulated by nucleoskeletal stiffness. Mechanical properties of lamin A/C contribute to the nucleoskeletal stiffness and consequently to the regulation of cell migration and differentiation. Nuclear lamin A/C determines cell migration through the regulation of nucleoskeletal stiffness and rigidity and involve in nuclear-cytoskeletal coupling. Moreover, lamin A/C is the essential core module regulating stem cell differentiation. The cells with higher migration ability tend to have enhanced differentiation potential, while the optimum amount of lamin A/C in migration and differentiation of MSCs is in conflict. This contrary phenomenon may be the result of mechanical microenvironment modulation.

Background Leymus secalinus is a pioneer plant grown in the Zoige desertified alpine grassland and it is also one of the dominant plant species used for environmental remediation. L. secalinus plays a large role in vegetation reconstruction in sandy land, but the abundance and diversity of its endophytes have not yet been investigated. Objectives This study was performed to investigate the changes in the endophytic bacterial community structure of L. secalinus under different ecological environments and to analyze the effects of environmental changes and different plant tissues on the L. secalinus endophytic bacteria. Methods Leaf, stem, and root tissue samples of L. secalinus were collected from Zoige Glassland (Alpine sandy land) and an open field nursery (Control). DNA was extracted and the 16S ribosomal DNA was amplified. The sequence library was sequenced on an Illumina MiSeq platform and clustered by operational taxonomic units (OTUs). α-diversity and β-diversity analyses, species diversity analyses, functional prediction, and redundancy (RDA) analyses for the soil physicochemical properties were conducted. Results α-diversity and β-diversity analyses showed that the endophytic bacteria in L. secalinus varied in different areas and tissues. The abundance of Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, which is related to nitrogen fixation, increased significantly in the L. secalinus found in the Zoige Grassland. Moreover, the abundance of nutrition metabolism and anti-stress abilities increased in functional prediction in the desert samples. The soil physicochemical properties had an insignificant influence on bacterial diversity. Conclusion The changes in the endophytic bacterial community structure in L. secalinus were significant and were caused by environmental alterations and plant choice. The endophytic bacteria in L. secalinus grown in alpine sandy land may have greater anti-stress properties and the ability to fix nitrogen, which has potential value in environmental remediation and agricultural production.

Rhizosphere microorganisms are thought to play a crucial role in the promotion of plant growth and health. Carex praeclara and Leymus secalinus are dominant plant species that have colonized the desertification land of Alpine wetland grasslands in Zoige. There is a lack of comprehensive research on their rhizosphere microbes. In this study, we used deep shotgun metagenomic sequencing to analyze the microbial community and functional composition of the rhizosphere and corresponding non-rhizosphere soils of C. praeclara and L. secalinus. The microbial diversity and structure exhibited a remarkable difference among the rhizosphere and non-rhizosphere samples, and the predominant taxa included Actinobacteria, Proteobacteria, Acidobacteria and Chloroflexi in all the samples. Genes that were over-represented include those involved in the acquisition of nutrients, stress responses, transposable elements and plant growth promotion suggest that the interactions between microbe-plant and microbe-microbe are more intense in the rhizosphere soil. The relative abundances of pivotal genes that participate in microbial nitrogen (N) and phosphorus (P) transformation were higher in the rhizosphere soil than in the non-rhizosphere soil, indicating the enhancement of potential soil N- and P-cycling in the plant rhizosphere. Our findings provide valuable information on the structure and function of the microbial communities of the C. praeclara and L. secalinus rhizospheres and lay a foundation for the further use of C. praeclara and L. secalinus to increase vegetation coverage, improve soil properties and restore the ecological function of degraded alpine sandy land.