Chloroplast DNA-based genetic variation of Rosa roxburghii in Southwest China:Phylogeography and conservation implications

Rosa roxburghii Tratt.is a well-known commercial horticultural crop in China with nutritional and medicinal value.Wild germplasms of this species are mainly distributed in Southwest China but the population is decreasing due to continuous exploitation,habitat destruction,and fragmentation.Therefore,assessing the genetic diversity and phylogeography is essential for efficient conservation.Herein,two chloroplast intergenic spacers(trnL-trnF and accD-psaI)were investigated in 255 individuals from 29 R.roxburghii populations and 18 haplotypes(H1–H18)were identified.High levels of haplotype diversity(Hd=0.829)and nucleotide diversity(π=1.3×10^(−3))were detected in these populations.Also,the genetic variation representing 86.4%of the total variation was detected by an analysis of molecular variance.A significant correlation was established between genetic divergence and geographic distance by the Mantel test(r=0.204,P=0.04,9999 permutations),suggesting the isolation-by-distance model.A significantly higher Nst than Gst(Nst=0.257,Gst=0.136,P<0.05)indicated the phylogeographic structure of R.roxburghii.Further phylogeographic analysis revealed rapid range expansion in the population,probably between 647073 and 217848 years ago.The primary processes shaping the genetic patterns of the R.roxburghii populations included restricted gene flow with isolation distance within clades 1-8,2-3,and overall,contiguous expansion within clades 1-3 and 3-2,past fragmentation,and/or long-distance colonization within clades 1-9 and 2-2.Conservation priority should be given to the core populations GZ,FQ,DF,DS,xy,AL,LC,PB,and XY in the Yunnan-Guizhou Plateau,NZ and MX in the Qingling-Bashan mountains,and MN in the Hengduan mountains,where an in situ preservation and management strategy should be applied.

Single-cell transcriptome reveals core cell populations and androgen-RXFP2 axis involved in deer antler full regeneration

Deer antlers constitute a unique mammalian model for the study of both organ formation in postnatal life and annual full regeneration.Previous studies revealed that these events are achieved through the proliferation and differentiation of antlerogenic periosteum(AP)cells and pedicle periosteum(PP)cells,respectively.As the cells resident in the AP and the PP possess stem cell attributes,both antler generation and regeneration are stem cell-based processes.However,the cell composition of each tissue type and molecular events underlying antler development remain poorly characterized.Here,we took the approach of single-cell RNA sequencing(scRNA-Seq)and identified eight cell types(mainly THY1^(+)cells,progenitor cells,and osteochondroblasts)and three core subclusters of the THY1^(+)cells(SC2,SC3,and SC4).Endothelial and mural cells each are heterogeneous at transcriptional level.It was the proliferation of progenitor,mural,and endothelial cells in the activated antler-lineage-specific tissues that drove the rapid formation of the antler.We detected the differences in the initial differentiation process between antler generation and regeneration using pseudotime trajectory analysis.These may be due to the difference in the degree of stemness of the AP-THY1+and PP-THY1^(+)cells.We further found that androgen-RXFP2 axis may be involved in triggering initial antler full regeneration.Fully deciphering the cell composition for these antler tissue types will open up new avenues for elucidating the mechanism underlying antler full renewal in specific and regenerative medicine in general.