Sclerotinia stem rot (SSR), caused by the oxalate-secreting necrotrophic fungal pathogen Sclerotinia sclerotiorum, is one of the devastating diseases that causes significant yield loss in soybean (Glycine max). Until now, effective control of the pathogen is greatly limited by a lack of strong resistance in available commercial soybean cultivars. In this study, transgenic soybean plants overexpressing an oxalic acid (OA)-degrading oxalate oxidase gene OXO from wheat were generated and evaluated for their resistance to S. sclerotiorum. Integration and expression of the transgene were confirmed by Southern and western blot analyses. As compared with non-transformed (NT) control plants, the transgenic lines with increased oxalate oxidase activity displayed significantly reduced lesion sizes, i.e., by 58.71–82.73% reduction of lesion length in a detached stem assay (T3 and T4 generations) and 76.67–82.0% reduction of lesion area in a detached leaf assay (T4 generation). The transgenic plants also showed increased tolerance to the externally applied OA (60 mM) relative to the NT controls. Consecutive resistance evaluation further confirmed an enhanced and stable resistance to S. sclerotiorum in the T3 and T4 transgenic lines. Similarly, decreased OA content and increased hydrogen peroxide (H2O2) levels were also observed in the transgenic leaves after S. sclerotiorum inoculation. Quantitative real-time polymerase chain reaction analysis revealed that the expression level of OXO reached a peak at 1 h and 4 h after inoculation with S. sclerotiorum. In parallel, a significant up-regulation of the hypersensitive response-related genes GmNPR1-1, GmNPR1-2, GmSGT1, and GmRAR occurred, eventually induced by increased release of H2O2 at the infection sites. Interestingly, other defense-related genes such as salicylic acid-dependent genes (GmPR1, GmPR2, GmPR3, GmPR5, GmPR12 and GmPAL), and ethylene/jasmonic acid-dependent genes (GmAOS, GmPPO) also exhibited higher expression levels in the transgenic plants than in the NT controls. Our results demonstrated that overexpression of OXO enhances SSR resistance by degrading OA secreted by S. sclerotiorum and increasing H2O2 levels, and eliciting defense responses mediated by multiple signaling pathways.
Arid environments provide ideal ground for investigating the mechanisms of adaptive evolution. High temperatures and low water availability are relentless stressors for many endotherms, including birds; yet birds persist in deserts. While physiological adaptation probably involves metabolic phenotypes, the underlying mechanisms (plasticity, genetics) are largely uncharacterized. To explore this, we took an intraspecific approach that focused on a species that is resident over a mesic to arid gradient, the Karoo scrub‐robin (Cercotrichas coryphaeus). Specifically, we integrated environmental (climatic and primary productivity), physiological (metabolic rates: a measure of energy expenditure), genotypic (genetic variation underlying the machinery of energy production) and microbiome (involved in processing food from where energy is retrieved) data, to infer the mechanism of physiological adaptation. We that found the variation in energetic physiology phenotypes and gut microbiome composition are associated with environmental features as well as with variation in genes underlying energy metabolic pathways. Specifically, we identified a small list of candidate adaptive genes, some of them with known ties to relevant physiology phenotypes. Together our results suggest that selective pressures on energetic physiology mediated by genes related to energy homeostasis and possibly microbiota composition may facilitate adaptation to local conditions and provide an explanation to the high avian intraspecific divergence observed in harsh environments. 相似文献
Giving access to sequence and annotation data for genome assemblies is important because, while facilitating research, it places both assembly and annotation quality under scrutiny, resulting in improvements to both. Therefore we announce Avianbase, a resource for bird genomics, which provides access to data released by the Avian Phylogenomics Consortium.Access to complete genome sequences provides the first step towards the understanding of the biology of organisms. It is the template that underpins the phenotypic characteristics of individuals and ultimately separates species due to the accumulation and fixation of mutations over evolutionary timescales. In terms of the available genomic datasets for species, birds, as our more distant relatives, have been historically underrepresented. The high cost of sequencing and annotation in the past led to a bias towards accumulating data for species that are either established model organisms or economically significant (that is, chicken, turkey and duck, representing two sister orders within the Galloanseriformes clade from the large and diverse phylogeny of birds). The recent release of genome assemblies and initial predictions of protein-coding genes [1-4] for 44 bird species, including representatives from all major branches of the bird phylogeny, is, therefore, highly significant.One of the major challenges with the release of this number of newly sequenced genomes and the many more to come [5] is how to make these available to the various research communities in a way that supports basic research. Providing access to the sequences and initial annotations in the format of text files will limit the potential usage of the data as they require significant resources, including bioinformatics personnel and computer infrastructure in place to access and mine - for example, searching for genes belonging to certain protein families or searching for orthologous genes. These overheads pose a serious bottleneck that can hinder research and requires concerted action by the relevant research communities.Once genomes are submitted to public databases, genome-wide annotations are frequently generated and released either via the Ensembl project [6] or by the National Center for Biotechnology Information [7] and sequence and annotation are then made visually available online in integrated views via the Ensembl or the University of California Santa Cruz (UCSC) genome browsers [8]. These systems provide search facilities, sequence alignment tools like BLAT/BLAST and various analysis tools to facilitate subsetting and computational retrieval of the data, including UCSC’s Table Browser or Ensembl’s Perl and REST APIs and BioMart system.While these systems have become almost indispensable for research, not all sequenced genomes are annotated and displayed in genome browsers. Full genome annotation remains time consuming and resource intensive: a full evidence-based Ensembl genebuild takes approximately 4 months. Thus, the list of species represented is currently limited and depends on various factors, including the completeness of the assembled genome sequence and the overall demand in the scientific community for the resources, including whether the species is a model organism (for example, human or mouse), economically important (for example, farmed animals) or of specific phylogenetic interest. Many of the recently sequenced bird genomes do not obviously fall within these categories. 相似文献
The proliferation and osteogenic capacity of mesenchymal stem cells (MSCs) needs to be improved for their use in cell-based therapy for osteoporosis. (?)-Epigallocatechin-3-gallate (EGCG), one of the green tea catechins, has been widely investigated in studies of osteoblasts and osteoclasts. However, no consensus on its role as an osteogenic inducer has been reached, possibly because of the various types of cell lines examined and the range of concentrations of EGCG used. In this study, the osteogenic effects of EGCG are studied in primary human bone-marrow-derived MSCs (hBMSCs) by detecting cell proliferation, alkaline phosphatase (ALP) activity and the expression of relevant osteogenic markers. Our results show that EGCG has a strong stimulatory effect on hBMSCs developing towards the osteogenic lineage, especially at a concentration of 5 μM, as evidenced by an increased ALP activity, the up-regulated expression of osteogenic genes and the formation of bone-like nodules. Further exploration has indicated that EGCG directes osteogenic differentiation via the continuous up-regulation of Runx2. The underlying mechanism might involve EGCG affects on osteogenic differentiation through the modulation of bone morphogenetic protein-2 expression. EGCG has also been found to promote the proliferation of hBMSCs in a dose-dependent manner. This might be associated with its antioxidative effect leading to favorable amounts of reactive oxygen species in the cellular environment. Our study thus indicates that EGCG can be used as a pro-osteogenic agent for the stem-cell-based therapy of osteoporosis. 相似文献
The Hedgehog (Hh) gene family codes for a class of secreted proteins composed of two active domains that act as signalling molecules during embryo development, namely for the development of the nervous and skeletal systems and the formation of the testis cord. While only one Hh gene is found typically in invertebrate genomes, most vertebrates species have three (Sonic hedgehog – Shh; Indian hedgehog – Ihh; and Desert hedgehog – Dhh), each with different expression patterns and functions, which likely helped promote the increasing complexity of vertebrates and their successful diversification. In this study, we used comparative genomic and adaptive evolutionary analyses to characterize the evolution of the Hh genes in vertebrates following the two major whole genome duplication (WGD) events. To overcome the lack of Hh-coding sequences on avian publicly available databases, we used an extensive dataset of 45 avian and three non-avian reptilian genomes to show that birds have all three Hh paralogs. We find suggestions that following the WGD events, vertebrate Hh paralogous genes evolved independently within similar linkage groups and under different evolutionary rates, especially within the catalytic domain. The structural regions around the ion-binding site were identified to be under positive selection in the signaling domain. These findings contrast with those observed in invertebrates, where different lineages that experienced gene duplication retained similar selective constraints in the Hh orthologs. Our results provide new insights on the evolutionary history of the Hh gene family, the functional roles of these paralogs in vertebrate species, and on the location of mutational hotspots. 相似文献
Shiga toxin-producing Escherichia coli (STEC) strains (n = 194) representing 43 serotypes and E. coli K-12 were examined for clustered regularly interspaced short palindromic repeat (CRISPR) arrays to study genetic relatedness among STEC serotypes. A subset of the strains (n = 81) was further analyzed for subtype I-E cas and virulence genes to determine a possible association of CRISPR elements with potential virulence. Four types of CRISPR arrays were identified. CRISPR1 and CRISPR2 were present in all strains tested; 1 strain also had both CRISPR3 and CRISPR4, whereas 193 strains displayed a short, combined array, CRISPR3-4. A total of 3,353 spacers were identified, representing 528 distinct spacers. The average length of a spacer was 32 bp. Approximately one-half of the spacers (54%) were unique and found mostly in strains of less common serotypes. Overall, CRISPR spacer contents correlated well with STEC serotypes, and identical arrays were shared between strains with the same H type (O26:H11, O103:H11, and O111:H11). There was no association identified between the presence of subtype I-E cas and virulence genes, but the total number of spacers had a negative correlation with potential pathogenicity (P < 0.05). Fewer spacers were found in strains that had a greater probability of causing outbreaks and disease than in those with lower virulence potential (P < 0.05). The relationship between the CRISPR-cas system and potential virulence needs to be determined on a broader scale, and the biological link will need to be established. 相似文献