Transcriptome sequencing and microsatellite marker discovery in Ailanthus altissima (Mill.) Swingle (Simaroubaceae)

Molecular Biology Reports - Ailanthus altissima Swingle, is a tree species native to East Asia and has a great potential in decorative, bioenergy and industrial applications in many countries. To...     

Molecular phylogeography of four endemic Sagittaria species (Alismataceae) in the Sino‐Japanese Floristic Region of East Asia

To reveal the role of climate oscillations of the Quaternary in forming the contemporary plant diversity in the temperate Sino‐Japanese Floristic Region of mainland China, we assess the phylogeographical patterns of four Sagittaria species in the region using sequence data from plastid DNA non‐coding regions (psbA‐trnH, the rpl16 intron and trnC‐ycf6) and the internal transcribed spacers of nuclear ribosomal DNA (nrITS). Based on both datasets, the divergence time among the four studied species was estimated to fall in the Late Tertiary (plastid DNA: 7.1–13.7 Mya; ITS: 11.1–16.1 Mya). The ancestral distribution analyses revealed that regions with a great diversity in topography, climate and ecological conditions, e.g. the Hengduan Mountains, Central China and East China, were the areas where the endemics originated. Mismatch distribution analyses revealed that each species had experienced a range expansion in response to Quaternary climatic oscillations. Our findings contradict the hypothesis of Quaternary origins of the endemic Sagittaria spp.; we support the view that modern species in the Northern Hemisphere originated mostly during the Tertiary. Range expansion may have profoundly modified the current distribution ranges of Sagittaria species in the Sino‐Japanese Floristic Region. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2016, 180 , 6–20.     

The effects of density on size-dependent gender plasticity in the monoecious species Sagittaria potamogetifolia (Alismataceae)

Aim

To test the fitness-gain curve model proposes that cosexual plants adjust their sex ratios and resource allocation depending on their size. In this study, the monoecious species Sagittaria potamogetifolia was used as a model to determine the effects of plant size and density on gender modification and reproductive allocation.

The complete chloroplast genome sequence of <Emphasis Type="Italic">Dodonaea viscosa</Emphasis>: comparative and phylogenetic analyses

The plant chloroplast (cp) genome is a highly conserved structure which is beneficial for evolution and systematic research. Currently, numerous complete cp genome sequences have been reported due to high throughput sequencing technology. However, there is no complete chloroplast genome of genus Dodonaea that has been reported before. To better understand the molecular basis of Dodonaea viscosa chloroplast, we used Illumina sequencing technology to sequence its complete genome. The whole length of the cp genome is 159,375 base pairs (bp), with a pair of inverted repeats (IRs) of 27,099 bp separated by a large single copy (LSC) 87,204 bp, and small single copy (SSC) 17,972 bp. The annotation analysis revealed a total of 115 unique genes of which 81 were protein coding, 30 tRNA, and four ribosomal RNA genes. Comparative genome analysis with other closely related Sapindaceae members showed conserved gene order in the inverted and single copy regions. Phylogenetic analysis clustered D. viscosa with other species of Sapindaceae with strong bootstrap support. Finally, a total of 249 SSRs were detected. Moreover, a comparison of the synonymous (Ks) and nonsynonymous (Ka) substitution rates in D. viscosa showed very low values. The availability of cp genome reported here provides a valuable genetic resource for comprehensive further studies in genetic variation, taxonomy and phylogenetic evolution of Sapindaceae family. In addition, SSR markers detected will be used in further phylogeographic and population structure studies of the species in this genus.     

Demographic history and population genetic structure of <Emphasis Type="Italic">Hagenia abyssinica</Emphasis> (Rosaceae), a tropical tree endemic to the Ethiopian highlands and eastern African mountains

The distribution of genetic diversity among natural populations is significantly shaped by geographical and environmental heterogeneity. The key objectives of this study were to outline the population genetic structure and to investigate the effects of historical and current factors in shaping the population structure of an endemic tropical tree, Hagenia abyssinica. We used 11 polymorphic microsatellites to estimate genetic variability and evaluate gene flow among natural populations of H. abyssinica. Further, we employed ecological niche modeling approaches, to analyze the demographic history and map potential distributions of H. abyssinica during the Last Glacial Maximum and the present. Significant levels of genetic diversity (H _O = 0.477, H _E = 0.439) were observed among the sampled locations. High coefficient of genetic differentiation (F _ST = 0.32) and considerable genetic variation within the sampled locations (68.01%) were detected. Our results indicated the existence of three genetic groups with limited gene exchange and revealed positive correlations (r = 0.425, P < 0.05) between genetic diversity and geo-graphic distance. The ecological niche modeling (ENM) results support the existence of three distribution zones during the Last Glacial Maximum (LGM), with high probability of occurrence (0.8–1.0), and indicated slight distribution disturbances during and after the LGM. The fundamental patterns of genetic diversity and population structuring of H. abyssinica result from a combination of both environmental and geographical factors, including long-term isolation by distance and characteristic life history of this species. Our ENM results identified three zones that could have served as glacial refugia for this species and lay a foundation for further studies, outlining demographic histories and population structures of Afromontane species.     

Cryptic diversity within the African aquatic plant Ottelia ulvifolia (Hydrocharitaceae) revealed by population genetic and phylogenetic analyses

Journal of Plant Research - Revealing cryptic diversity is of great importance for effective conservation and understanding macroevolution and ecology of plants. Ottelia, a typical example of...