Yong-Hong Zhou

Structural characterization and antioxidant activities of polysaccharides extracted from Epimedium acuminatum

The polysaccharides were extracted from Epimedium acuminatum by hot water extraction, ultrasonic-assisted extraction, enzyme extraction, and microwave-assisted extraction. The physicochemical properties of Epimedium polysaccharides were then determined by chemical composition analysis, Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) analysis. Further, the antioxidant activities were studied via different methods, including DPPH assay, ABTS assay, FRAP assay and AAPH-induced erythrocyte hemolysis assay. Results showed that the physicochemical properties of different polysaccharides were similar. Antioxidant assay indicated that four polysaccharides exhibited significant antioxidant activities in a dose-dependent manner. The antioxidant activities of the polysaccharides which obtained by hot water extraction were higher than those of other polysaccharides. Overall, E. acuminatum polysaccharides might be used as potential natural antioxidant.

Phylogeny and evolutionary history of Leymus(Triticeae; Poaceae) based on a single-copy nuclear gene encoding plastid acetyl-CoA carboxylase

BackgroundSingle- and low- copy genes are less likely subject to concerted evolution, thus making themselves ideal tools for studying the origin and evolution of polyploid taxa. Leymus is a polyploid genus with a diverse array of morphology, ecology and distribution in Triticeae. The genomic constitution of Leymus was assigned as NsXm, where Ns was presumed to be originated from Psathyrostachys, while Xm represented a genome of unknown origin. In addition, little is known about the evolutionary history of Leymus. Here, we investigate the phylogenetic relationship, genome donor, and evolutionary history of Leymus based on a single-copy nuclear Acc1 gene.ResultsTwo homoeologues of the Acc1 gene were isolated from nearly all the sampled Leymus species using allele-specific primer and were analyzed with those from 35 diploid taxa representing 18 basic genomes in Triticeae. Sequence diversity patterns and genealogical analysis suggested that (1) Leymus is closely related to Psathyrostachys, Agropyron, and Eremopyrum; (2) Psathyrostachys juncea is an ancestral Ns-genome donor of Leymus species; (3) the Xm genome in Leymus may be originated from an ancestral lineage of Agropyron and Eremopyrum triticeum; (4) the Acc1 sequences of Leymus species from the Qinghai-Tibetan plateau are evolutionarily distinct; (5) North America Leymus species might originate from colonization via the Bering land bridge; (6) Leymus originated about 11-12MYA in Eurasia, and adaptive radiation might have occurred in Leymus during the period of 3.7-4.3 MYA and 1.7-2.1 MYA.ConclusionLeymus species have allopolyploid origin. It is hypothesized that the adaptive radiation of Leymus species might have been triggered by the recent upliftings of the Qinghai-Tibetan plateau and subsequent climatic oscillations. Adaptive radiation may have promoted the rapid speciation, as well as the fixation of unique morphological characters in Leymus. Our results shed new light on our understanding of the origin of Xm genome, the polyploidization events and evolutionary history of Leymus that could account for the rich diversity and ecological adaptation of Leymus species.

Introgression of Chromosome 3Ns from Psathyrostachys huashanica into Wheat Specifying Resistance to Stripe Rust

Wheat stripe rust is a destructive disease in the cool and humid wheat-growing areas of the world. Finding diverse sources of stripe rust resistance is critical for increasing genetic diversity of resistance for wheat breeding programs. Stripe rust resistance was identified in the alien species Psathyrostachys huashanica, and a wheat- P. huashanica amphiploid line (PHW-SA) with stripe rust resistance was reported previously. In this study, a P. huashanica 3Ns monosomic addition line (PW11) with superior resistance to stripe rust was developed, which was derived from the cross between PHW-SA and wheat J-11. We evaluated the alien introgressions PW11-2, PW11-5 and PW11-8 which were derived from line PW11 for reaction to new Pst race CYR32, and used molecular and cytogenetic tools to characterize these lines. The introgressions were remarkably resistant to CYR32, suggesting that the resistance to stripe rust of the introgressions thus was controlled by gene(s) located on P. huashanica chromosome 3Ns. All derived lines were cytologically stable in term of meiotic chromosome behavior. Two 3Ns chromosomes of P. huashanica were detected in the disomic addition line PW11-2. Chromosomes 1B of substitution line PW11-5 had been replaced by a pair of P. huashanica 3Ns chromosomes. In PW11-8, a small terminal segment from P. huashanica chromosome arm 3NsS was translocated to the terminal region of wheat chromosomes 3BL. Thus, this translocated chromosome is designated T3BL-3NsS. These conclusions were further confirmed by SSR analyses. Two 3Ns-specific markers Xgwm181 and Xgwm161 will be useful to rapidly identify and trace the translocated fragments. These introgressions, which had significant characteristics of resistance to stripe rust, could be utilized as novel germplasms for wheat breeding.

Phylogenetic relationships between Hystrix and its closely related genera (Triticeae; Poaceae) based on nuclear Acc1, DMC1 and chloroplast trnL-F sequences.

To estimate the phylogenetic relationship of polyploid Hystrix in Triticeae, two single-copy nuclear genes (Acc1 and DMC1) and chloroplast trnL-F sequences of six Hystrix taxa were analyzed with those of nine Leymus species (NsXm), four Elymus species (StH) and 13 diploid taxa from seven monogenomic genera. Phylogenetic analyses reveal that Hystrix taxa contain two distinct types of genome constitution, despite the overall morphological and ecological similarity among Hystrix taxa. One type of genome constitution is StH (Hy. patula) as Elymus, the other is NsXm (Hy. californica, Hy. coreana, Hy. duthiei, Hy. duthiei ssp. longearistata and Hy. komarovii) as Leymus. The St, H and Ns genomes in Hystrix are donated by Pseudoroegneria, Hordeum and Psathyrostachys, respectively. The donor of the Xm genome is closely related to Agropyron (P). The trnL-F data especially indicate that there has been a maternal haplotype polymorphism in Hystrix species. Based on these results, we suggest that Hy. coreana, Hy. duthiei, Hy. duthiei ssp. longearistata, Hy. komarovii and Hy. californica should be included in the genus Leymus, and Hy. patula in the genus Elymus.

Extraction, antioxidant and antimicrobial activities of Epimedium acuminatum Franch. polysaccharide

Polysaccharides from Epimedium acuminatum were extracted by hot water and optimized with response surface methodology. The optimal conditions of the extraction were determined to be the ratio of water to raw material of 29.61, extraction temperature of 85.67°C and extraction time of 3.57 h. Under these optimal conditions, the yield of polysaccharide was 8.21%, which was well matched with the predictive yield (8.23%). Moreover, three purified fractions (EAP40-1, EAP60-1 and EAP80-2) were obtained for further chemical analysis, antioxidant activity analysis and antimicrobial activity analysis. EAP40-1 with molecular weight of 138,884 Da showed the best radical scavenging activity. Meanwhile, EAP60-1 with molecular weight of 114,667 Da was found to exhibit significant antihemolytic activity and antimicrobial activity.

Selection of reference genes for normalization of qRT-PCR analysis of differentially expressed genes in soybean exposed to cadmium.

Accurate normalization of gene expression with qRT-PCR depends on the use of appropriate reference genes (RGs) for the species under a given set of experimental conditions. Multiple RGs for gene expression analysis of soybean exposed to heavy metal stress treatment have not been reported in the literature. In this study, we evaluated the expression stability of ten candidate RGs in leaves, roots and stems of two soybean cultivars exposed to cadmium (Cd). Based on the geNorm and NormFinder analysis, ACT3, PP2A, ELF1B and F-box were the most stable RGs in these gene expression studies. In contrast, G6PD, UBC2, TUB, and ELF1A were the most variable ones and should not be used as RGs in these experimental conditions.

Evolutionary dynamics of the Pgk1 gene in the polyploid genus Kengyilia (Triticeae: Poaceae) and its diploid relatives.

The level and pattern of nucleotide variation in duplicate gene provide important information on the evolutionary history of polyploids and divergent process between homoeologous loci within lineages. Kengyilia is a group of allohexaploid species with the StYP genomic constitutions in the wheat tribe. To investigate the evolutionary dynamics of the Pgk1 gene in Kengyilia and its diploid relatives, three copies of Pgk1 homoeologues were isolated from all sampled hexaploid Kengyilia species and analyzed with the Pgk1 sequences from 47 diploid taxa representing 18 basic genomes in Triticeae. Sequence diversity patterns and genealogical analysis suggested that (1) Kengyilia species from the Central Asia and the Qinghai-Tibetan plateau have independent origins with geographically differentiated P genome donors and diverged levels of nucleotide diversity at Pgk1 locus; (2) a relatively long-time sweep event has allowed the Pgk1 gene within Agropyron to adapt to cold climate triggered by the recent uplifts of the Qinghai-Tibetan Plateau; (3) sweep event and population expansion might result in the difference in the dN/dS value of the Pgk1 gene in allopatric Agropyron populations, and this difference may be genetically transmitted to Kengyilia lineages via independent polyploidization events; (4) an 83 bp MITE element insertion has shaped the Pgk1 loci in the P genome lineage with different geographical regions; (5) the St and P genomes in Kengyilia were donated by Pseudoroegneria and Agropyron, respectively, and the Y genome is closely related to the Xp genome of Peridictyon sanctum. The interplay of evolutionary forces involving diverged natural selection, population expansion, and transposable events in geographically differentiated P genome donors could attribute to geographical differentiation of Kengyilia species via independent origins.

Phylogenetic relationships and Y genome origin in Elymus L. sensu lato (Triticeae; Poaceae) based on single-copy nuclear Acc1 and Pgk1 gene sequences.

To estimate the origin and genomic relationships of the polyploid species within Elymus L. sensu lato, two unlinked single-copy nuclear gene (Acc1 and Pgk1) sequences of eighteen tetraploids (StH and StY genomes) and fourteen hexaploids (StStH, StYP, StYH, and StYW genomes) were analyzed with those of 35 diploid taxa representing 18 basic genomes in Triticeae. Sequence and phylogenetic analysis suggested that: (1) the St, H, W, and P genomes were donated by Pseudoroegneria, Hordeum, Australopyrum, and Agropyron, respectively, while the Y genome is closely related to the Xp genome in Peridictyon sanctum; (2) different hexaploid Elymus s.l. species may derived their StY genome from different StY genome tetraploid species via independent origins; (3) due to incomplete lineage sorting and/or hybridization events, the genealogical conflict between the two gene trees suggest introgression involving some Elymus s.l. species, Pseudoroegneria, Agropyron and Aegilops/Triticum; (4) it is reasonable to recognize the StH genome species as Elymus sensu stricto, the StY genome species as Roegneria, the StYW genome species as Anthosachne, the StYH genome species as Campeiostachys, and the StYP genome species as Kengyilia. The occurrence of multiple origin and introgression could account for the rich diversity and ecological adaptation of Elymus s.l. species.

Phylogenetic relationships of species in Pseudoroegneria (Poaceae: Triticeae) and related genera inferred from nuclear rDNA ITS (internal transcribed spacer) sequences

To evaluate the phylogenetic relationships of species in Pseudoroegneria and related genera, the nuclear ribosomal internal transcribed spacer (ITS) sequences were analyzed for eighteen Pseudoroegneria (St), two Elytrigia (EeSt), two Douglasdeweya (StP), three Lophopyrum (Ee and Eb), three Agropyron (P), two Hordeum (H), two Australopyrum (W) and two Psathyrostachys (Ns) accessions. The main results were: (i) Pseudoroegneria gracillima, P. stipifolia, P. cognata and P. strigosa (2x) were in one clade, while P. libanotica, P. tauri and P. spicata (2x) were in the other clade, indicating there are the differentiations of St genome among diploid Pseudoroegneria species; (ii) P. geniculata ssp. scythica, P. geniculata ssp. pruinifera, Elytriga caespitosa and Et. caespitosa ssp. nodosa formed the EeSt clade with 6-bp indel in ITS1 regions; and (iii) Douglasdeweya wangii, D. deweyi, Agropyron cristatum and A. puberulum comprised the P clade. It is unreasonable to treat P. geniculata ssp. scythica and P. geniculata ssp. pruinifera as the subspecies of P. geniculata, and they should be transferred to a new genus Trichopyrum, which consists of species with EeSt genomes. It is also suggested that one of the diploid donor of D. wangii and D. deweyi is derived from Agropyron species, and it is reasonable to treat tetraploid species with StP genomes into Douglasdeweya.

Phylogenetic Analysis of Leymus (Poaceae: Triticeae) Inferred from Nuclear rDNA ITS Sequences

To investigate the phylogenetic relationships of polyploid Leymus (Poaceae: Triticeae), sequences of the nuclear rDNA internal transcribed spacer region (ITS) were analyzed for 34 Leymus accessions representing 25 species, together with three Psathyrostachys species (Ns genome), two Pseudoroegneria (St genome) species, Lophopyrumxa0elongatum (Ee genome), and Thinopyrumbessarabicum (Eb genome). The phylogenetic analyses (maximum likelihood and Bayesian inference) supported two major clades, one including 21 Leymus species and three Psathyrostachys species, the other with nine Leymus species and four diploid species. The ITS RNA secondary structure of the Leymus species was compared with that of their putative diploid donor. It is suggested that (1) the species from the same areas or neighboring geographic regions are closely related to each other; (2) L.xa0coreanus, L.xa0duthiei, L.xa0duthiei var. longearistatus, and L.xa0komarovii are closely related to other Leymus species, and it is reasonable to transfer these species from the genus Hystrix to Leymus; (3) the ITS sequences of Leymus are evolutionarily distinct; (4) the different Leymus species and different distribution of a species derived their Ns genome from different Psathyrostachys species; and (5) there is a close relationship among Leymus, Pseudoroegneria, Lophopyrum, and Thinopyrum, but it is difficult to presume that the St, Ee, and Eb genome may be the Xm genome donor of the Leymus species.