Biology subjects

Xia, X.

Publications and source records attributed to Xia, X..

At least 109 records · Page 6Linked to original sources

bioRxiv2020

CRISPR-Assisted DNA Detection, a novel dCas9-based DNA detection technique

Nucleic acid detection techniques are always critical to diagnosis, especially in the background of the present COVID-19 pandemic. The simple and rapid detection techniques with high sensitivity and specificity are always urgently needed. However, the current nucleic acid detection techniques are still limited the traditional amplification and hybridization. To overcome the limitation, we here develop a CRISPR/Cas9-assisted DNA detection (CADD). In this detection, DNA sample is incubated with a pair of capture sgRNAs (sgRNAa and sgRNAb) specific to a target DNA, dCas9, a signal readout-related probe, and an oligo-coated solid support beads or microplate at room temperature for 15 min. During this incubation, the dCas9-sgRNA-DNA complex is formed and captured on solid support by the capture sequence of sgRNAa and the signal readout-related probe is captured by the capture sequence of sgRNAb. Finally the detection result is reported by a fluorescent or colorimetric signal readout. This detection was verified by detecting DNA of bacteria, cancer cell and virus. Especially, by designing a set of sgRNAs specific to 15 high-risk human papillomaviruses (HPVs), the HPV infection in 64 clinical cervical samples were successfully detected by the method. All detections can be finished in 30 minutes at room temperature. This detection holds promise for rapid on-the-spot detection or point-of-care testing (POCT).

biochemistry↗

bioRxiv2020

Ripasudil in a model of pigmentary glaucoma

PurposeTo investigate the effects of Ripasudil (K-115), a Rho-kinase inhibitor, in a porcine model of pigmentary glaucoma. MethodsHallmark features of trabecular meshwork (TM), the principle structure of the outflow system affected in this model, were analyzed. In vitro TM cells and ex vivo perfused eyes were subjected to pigment dispersion followed by K-115 treatment (PK115). PK115 was compared to sham-treated controls (C) and pigment (P). Cytoskeletal alterations were assessed by F-actin labeling. TM cell phagocytosis of fluorescent targets was evaluated by flow cytometry. Cell migration was studied with a wound-healing assay. Intraocular pressure was continuously monitored and compared to after the establishment of the pigmentary glaucoma model and after treatment with K-115. ResultsIn vitro, the percentage of cells with stress fibers increased in response to pigment but declined sharply after treatment with K-115 (P: 32.8 +/- 2.9%; PK115: 11.6 +/- 3.3%, P < 0.001). Phagocytosis first declined but recovered after K-115 (P: 25.7+/-2.1%, PK115: 33.4+/-0.8%, P <0.01). Migration recuperated at 12h with K-115 treatment (P: 19.1+/-4.6 cells/high-power field, PK115: 42.5+/-1.6 cells/high-power field, P <0.001). Ex vivo, eyes became hypertensive from pigment dispersion but were normotensive after treatment with K-115 (P: 20.3 +/- 1.2 mmHg, PK115: 8.9 +/- 1.7 mmHg; P< 0.005). ConclusionIn vitro, K-115 reduced TM stress fibers, restored phagocytosis, and restored migration of TM cells. Ex vivo, K-115 normalized intraocular pressure.

pharmacology and toxicology↗

bioRxiv2020

Generation and Validation of Versatile Inducible CRISPRi Embryonic Stem Cell and Mouse Models

CRISPR-Cas9 has been widely used far beyond genome editing. Fusions of deactivated Cas9 (dCas9) to transcription effectors enable interrogation of the epigenome and controlling of gene expression. However the large transgene size of dCas9-fusion hinders its applications especially in somatic tissues. Here, we develop a robust CRISPR interference (CRISPRi) system by transgenic expression of doxycycline (Dox) inducible dCas9-KRAB in mouse embryonic stem cells (iKRAB ESC). After introduction of specific gRNAs, the induced dCas9-KRAB efficiently maintains gene inactivation, though it exerts modest effects on active gene expression. Proper timing of Dox addition during cell differentiation or reprogramming allows us to study or screen spatiotemporally activated promoters or enhancers and thereby the gene functions. Furthermore, taking the ESC for blastocyst injection, we generate an iKRAB knockin (KI) mouse model that enables shut-down of gene expression and loss-of-function studies ex vivo and in vivo by a simple transduction of gRNAs. Thus, our inducible CRISPRi ESC line and KI mouse provide versatile and convenient platforms for functional interrogation and high-throughput screens of specific genes and potential regulatory elements in the setting of development or diseases.

genetics↗

bioRxiv2020

ERG orchestrates chromatin interactions to drive prostate cell fate reprogramming

While cancer is commonly perceived as a disease of dedifferentiation, the hallmark of early stage prostate cancer is paradoxically the loss of more plastic basal cells and the abnormal proliferation of more differentiated secretory luminal cells. However, the mechanism of prostate cancer pro-luminal differentiation is largely unknown. Through integrating analysis of the transcription factors (TFs) from 806 human prostate cancers, we have identified that ERG highly correlated with prostate cancer luminal subtyping. ERG overexpression in luminal epithelial cells inhibits its normal plasticity to transdifferentiate into basal lineage and ERG supersedes PTEN-loss which favors basal differentiation. ERG knock-out disrupted prostate cell luminal differentiation, whereas AR knock-out had no such effects. Trp63 is a known master regulator of prostate basal lineage. Through analysis of 3D chromatin architecture, we found that ERG binds and inhibits the enhancer activity and chromatin looping of a Trp63 distal enhancer, thereby silencing its gene expression. Specific deletion of the distal ERG binding site resulted in the loss of ERG-mediated inhibition of basal differentiation. Thus, ERG orchestrates chromatin interactions and regulates prostate cell lineage toward pro-luminal program, as its fundamental role on lineage differentiation in prostate cancer initiation.

cancer biology↗

bioRxiv2020

Single-cell transcriptome profiling an adult human cell atlas of 15 major organs

BackgroundAs core units of organ tissues, cells of various types play their harmonious rhythms to maintain the homeostasis of the human body. It is essential to identify the characteristics of cells in human organs and their regulatory networks for understanding the biological mechanisms related to health and disease. However, a systematic and comprehensive single-cell transcriptional profile across multiple organs of a normal human adult is missing. ResultsWe perform single-cell transcriptomes of 84,363 cells derived from 15 tissue organs of one adult donor and generate an adult human cell atlas. The adult human cell atlas depicts 252 subtypes of cells, including major cell types such as T, B, myeloid, epithelial, and stromal cells, as well as novel COCH+ fibroblasts and FibSmo cells, each of which is distinguished by multiple marker genes and transcriptional profiles. These collectively contribute to the heterogeneity of major human organs. Moreover, T cell and B cell receptor repertoire comparisons and trajectory analyses reveal direct clonal sharing of T and B cells with various developmental states among different tissues. Furthermore, novel cell markers, transcription factors and ligand-receptor pairs are identified with potential functional regulations in maintaining the homeostasis of human cells among tissues. ConclusionsThe adult human cell atlas reveals the inter- and intra-organ heterogeneity of cell characteristics and provides a useful resource in uncovering key events during the development of human diseases in the context of the heterogeneity of cells and organs.

cell biology↗

bioRxiv2020

The PK/PD Integration and Resistance of Ti lmi cosin Against Mycoplasma hyopneumoniae

Mycoplasma hyopneumoniae is the major pathogen causing enzootic pneumonia in pigs. M. hyopneumoniae infection can lead to considerable economic losses in the pig-breeding industry. Here, this study established a first-order absorption, one-compartment model to study the relationship between the pharmacokinetics/pharmacodynamics (PK/PD) index of tilmicosin against M. hyopneumoniae in vitro. We simulated the drug concentration of timicosin in the fluid lining the lung epithelia of pigs. The minimum inhibitory concentration (MIC) of tilmicosin against M. hyopneumoniae with an inoculum of 106 CFU/mL was 1.6 g/mL using the microdilution method. Static time-kill curves showed that, if the drug concentration >1 MIC, the antibacterial effect showed different degrees of inhibition. At 32 MIC, the amount of bacteria decreased by 3.16 log10 CFU/mL, thereby achieving a mycoplasmacidal effect. The M. hyopneumoniae count was reduced from 3.61 to 5.11 log10 CFU/mL upon incubation for 96 h in a dynamic model with a dose of 40-200 mg, thereby achieving mycoplasmacidal activity. The peak concentration by MIC (Cmax/MIC) and the area under the concentration-time curve over 96 h divided by the MIC (AUC0-96 h/MIC) were the best-fit PK/PD parameters for predicting the antibacterial activity of tilmicosin against M. hyopneumoniae (R2 = 0.99), suggesting that tilmicosin had concentration-dependent activity. The estimated value for Cmax/MIC and AUC0-96 h/MIC for 2log10 (CFU/mL) reduction and 3log10 (CFU/mL) reduction from baseline was 1.44 and 1.91, and 70.55 h and 96.72 h, respectively. Four M. hyopneumoniae strains (M1-M4) with reduced sensitivity to tilmicosin were isolated from the four dose groups. The susceptibility of these strains to tylosin, erythromycin and lincomycin was also reduced significantly. For sequencing analyses of 23S rRNA, an acquired A2058G transition in region V was found only in resistant M. hyopneumoniae strains (M3, M4). In conclusion, in an in vitro model, the effect of tilmicosin against M. hyopneumoniae was concentration-dependent and had a therapeutic effect. These results will help to design the optimal dosing regimen for tilmicosin in M. hyopneumoniae infection, and minimize the emergence of resistant bacteria.

pharmacology and toxicology↗

bioRxiv2020

Stem Cell Transplantation Rescued A Primary Open-Angle Glaucoma Mouse Model

Glaucoma is a leading cause of irreversible blindness. In this study, we investigated if exogenous stem cells are able to rescue a glaucoma mouse model with transgenic myocilin Y437H mutation and explored the possible mechanisms. Human trabecular meshwork stem cells (TMSCs) were intracamerally transplanted which reduced mouse intraocular pressure, increased outflow facility, protected the retinal ganglion cells and preserved their function. TMSC transplantation also significantly increased the TM cellularity, promoted myocilin secretion from TM cells into the aqueous humor to reduce endoplasmic reticulum stress, repaired the TM tissue with extracellular matrix modulation and ultrastructural restoration. Co-culturing TMSCs with myocilin mutant TM cells in vitro promoted TMSCs differentiating into phagocytic functional TM cells. RNA sequencing revealed that TMSCs had upregulated genes related to TM regeneration and neuroprotection. Our results uncovered therapeutic potential of TMSCs for curing glaucoma and elucidated possible mechanisms by which TMSCs achieve the treatment effect.

developmental biology↗

bioRxiv2020

Finding new cancer epigenetic and genetic biomarkers from cell-free DNA by combining SALP-seq and machine learning：esophageal cancer as an example

BackgroundCancer is an important public health problem worldwide and its early diagnosis and effective prognosis are critical for its treatment. In recent years, as a good material for cancer liquid biopsy, plasma cell-free DNA (cfDNA) has been widely analyzed by next generation sequencing (NGS) for finding new molecular markers for cancer diagnosis such as size, methylation and end coordinate. However, the current studies did not still involve esophageal cancer (ESCA), a main cancer that seriously threatens human health and life in China. Here we therefore tried to find new biomarkers for this cancer from cfDNA. Materials & methodsThirty cfDNA samples from 26 ESCA patients and 4 healthy people were used to construct the NGS libraries and sequenced by using SALP-seq. The sequencing data were analyzed with variant bioinformatics methods for finding ESCA molecular biomarkers. Results & conclusionWe identified 103 epigenetic markers (including 54 genome-wide and 49 promoter markers) and 37 genetic markers for ESCA. These markers provide new molecular biomarkers for ESCA diagnosis, prognosis and therapy. Importantly, this study provides a new pipeline for finding new molecular markers for cancers from cfDNA by combining SALP-seq and machine learning. Finally, by finding new molecular markers for ESCA from cfDNA, this study sheds important new insights on the clinical worth of cfDNA.

cancer biology↗

bioRxiv2019

The genome of Peronospora belbahrii reveals high heterozygosity, a low number of canonical effectors and CT-rich promoters

Along with Plasmopara destructor, Peronosopora belbahrii has arguably been the economically most important newly emerging downy mildew pathogen of the past two decades. Originating from Africa, it has started devastating basil production throughout the world, most likely due to the distribution of infested seed material. Here we present the genome of this pathogen and results from comparisons of its genomic features to other oomycetes. The assembly of the nuclear genome was ca. 35.4 Mbp in length, with an N50 scaffold length of ca. 248 kbp and an L50 scaffold count of 46. The circular mitochondrial genome consisted of ca. 40.1 kbp. From the repeat-masked genome 9049 protein-coding genes were predicted, out of which 335 were predicted to have extracellular functions, representing the smallest secretome so far found in peronosporalean oomycetes. About 16 % of the genome consists of repetitive sequences, and based on simple sequence repeat regions, we provide a set of microsatellites that could be used for population genetic studies of Pe. belbahrii. Peronospora belbahrii has undergone a high degree of convergent evolution, reflecting its obligate biotrophic lifestyle. Features of its secretome, signalling networks, and promoters are presented, and some patterns are hypothesised to reflect the high degree of host specificity in Peronospora species. In addition, we suggest the presence of additional virulence factors apart from classical effector classes that are promising candidates for future functional studies.

genomics↗

bioRxiv2019

Circadian regulation of microRNA-target chimeras in Drosophila

MicroRNA is critical coordinator to circadian regulation by silencing gene expression. Although many circadian related miRNAs and some of its target are known, the global functional miRNA-mRNA interaction networks remain poorly understand which is hindered by imperfect base-pairing between miRNA and target mRNA. In this study, we used CLEAR (Covalent Ligation of Endogenous Argonaute-bound RNAs) -CLIP (Cross-Linking and Immuno-Precipitation) to explore the regulatory functions of miRNAs in the circadian system by comparing the miRNA-mRNA interactions between the Drosophila wild-type strain w1118 and the Clk mutant Clkjrk. We unambiguously identified thousands of miRNA-mRNA interactions from CLEAR-CLIP data set at unprecedented depth in vivo for the first time. Among them, about 300 miRNA-mRNA interactions were involved in the regulation of circadian, in which miRNAs targeting core clock genes pdp1, tim and vri presented distinct changes in response to Clkjrk. Particularly, the mir-375-timeless interaction from CLER-CLIP shows important effects on circadian, this functional event occurred in the l-LNv neurons. Overexpression of mir-375 in tim neurons caused decreases in TIM content resulting in arrhythmicity of daily locomotion and changes of sleep. This present work provides a global view of miRNA targeting in the circadian rhythm.

molecular biology↗

bioRxiv2019

Volumetric two-photon imaging in live cells and embryos via axially gradient excitation

Two-photon microscopy(TPM) that features subcellular resolution, intrinsic optical sectioning ability, and deep penetration in sample is a powerful tool of bioimaging. However, the process of layer-by-layer scanning to form a 3D image inherently limits the volumetric imaging speed and significantly increases the phototoxicity. Here we develop a gradient TPM technique that enables rapid volumetric imaging by only acquiring two 2D images. By sequentially exciting the specimen with two axially elongated two-photon beams with complementary gradient intensities, the axial positions of fluorophores can be decoded from the intensity ratio of the paired images. We achieve an axial localization accuracy of 0.728 {+/-} 0.657 m, which is sufficient for rapid 3D subcellular imaging. We demonstrate the flexibility of the gradient TPM on a variety of sparsely labelled samples, including bead phantoms, mouse brain tissues, live macrophages and live nematode embryos. The results show that, compared with conventional TPM, the 3D imaging speed increases 6 folds while the photobleaching and photodamage are extremely reduced.

bioengineering↗

bioRxiv2019

Pair-wise Comparison Analysis for Multiple Pool-sep: an efficient method identified anthocyanin biosynthesis genes in rice pericarp

The complex traits are derived from multiple genes and exhibit a large variety of phenotypes. High-throughput sequencing technologies have become the new strategies for mapping the important traits of crops. However, these methods have their own disadvantages and limitations. Here we introduced Pair-wise Comparison Analysis for Multiple Pool-seq (PCAMP) for mapping the candidate genomic regions involved in anthocyanin biosynthesis in rice pericarp. In this protocol, the second filial generation (F2) populations obtained by crossing two parents with different target traits were divided into n (n>=3) subpopulations according to their phenotypes. Thirty phenotypically identical individuals were selected from each subpopulation and DNA samples were extracted to form a pool for sequencing. Finally, we compared the SNP-index between every two Pool-seqs to map the candidate genomic regions. We applied PCAMP to analyse F2 populations and successfully identified five known genes and five new candidate genomic regions for anthocyanin biosynthesis in rice pericarp. These results demonstrate that PCAMP is an efficient new method for dissecting the complex traits of crops.

molecular biology↗

bioRxiv2019

The genomic sequence and comparative genomic analysis of cultivated passion fruit(Passiflora edulis L.)

Cultivated passion fruit is a fruit tree widely cultivated in southern China, but little is known about its genomics, which seriously restricts the molecular genetics research of passion fruit. In this study, we analyzed the 165.7Mb representative genome sequences. The results showed that the passion fruit genome contained a large number of simple sequence repeats (SSR). Compared to the cassava and peach genomes, the passion fruit genome has 23,053 predicted genes. These genes can be aligned to 282 plant genomes. GO annotation indicated that these genes are involved in metabolic pathways of carbohydrates, organic acids, lipids and other molecules. KEGG pathway enrichment assigned these genes into five major categories and 19 secondary functions. Cluster analysis of gene families showed that 12,767 genes could be clustered into 9,868 gene families and 291 unique gene families. On the evolutionary relationship, the passion fruit is closely related to Populus trichocarpa and Ricinus communis, but the rate of evolution is slower. In summary, this genomic analysis result is informative, and will facilitate the future studies on gene functions of passion fruit.

genomics↗

bioRxiv2018

Rapid Geometric Feature Signaling In The Spiking Activity Of A Complete Population Of Tactile Nerve Fibers

Tactile feature extraction is essential to guide the dexterous manipulation of objects. The longstanding theory is that geometric features at each location of contact between hand and object are extracted from the spatial layout of the response of populations of tactile nerve fibers. However, recent evidence suggests that some features (edge orientation, e.g.) are extracted very rapidly (<200ms), casting doubt that this information relies on a spatial code, which ostensibly requires integrating responses over time. An alternative hypothesis is that orientation is conveyed in precise temporal spiking patterns. Here, we simulate, using a recently developed and validated model, the responses of tactile fibers from the entire human fingertip ([~]800 afferents) to edges indented into the skin. We show that edge orientation can be quickly (<50 ms) and accurately (<3{degrees}) decoded from the spatial pattern of activation across the afferent population, starting with the very first spike. Next, we implement a biomimetic decoder of edge orientation, consisting of a bank of oriented Gabor filters, designed to mimic the documented responses of cortical neurons. We find that the biomimetic approach leads to orientation decoding performance that approaches the limit set by optimal decoders and is actually more robust to changes in other stimulus features. Finally, we show that orientation signals, measured from single units in non-human primate cortex (2 macaque monkeys, 1 female), follow a time course consistent with that of their counterparts in the nerve. We conclude that a spatial code is fast and accurate enough to support object manipulation.

neuroscience↗

bioRxiv2018

A starless bias in the maximum likelihood phylogenetic methods

I analyzed various site pattern combinations in a 4-OTU case to identify sources of starless bias and parameter-estimation bias in likelihood-based phylogenetic methods, and reported three significant contributions. First, the likelihood method is odd in that it may not generate a star tree with sequences that are equidistant from each other. This behaviour, dubbed starless bias, happens in a 4-OTU tree when there is an excess (i.e., more than expected from a star tree and a substitution model) of conflicting phylogenetic signals supporting the three resolved topologies equally. Special site pattern combinations leading to rejection of a star tree, when sequences are equidistant from each other, were identified. Second, fitting gamma distribution to model rate heterogeneity over sites is strongly confounded with tree topology, especially in conjunction with the starless bias. I present examples to show dramatic differences in the estimated shape parameter between a star tree and a resolved tree. There may be no rate heterogeneity over sites (with the estimated > 10000) when a star tree is imposed, but < 1 (suggesting strong rate heterogeneity over sites) when an (incorrect) resolved tree is imposed. Thus, the dependence of "rate heterogeneity" on tree topology implies that "rate heterogeneity" is not a sequence-specific feature, cautioning against interpreting a small to mean that some sites are under strong purifying selection and others not. Thirdly, because there is no existing (and working) likelihood method for evaluating a star tree with continuous gamma-distributed rate, I have implemented the method for JC69 in a self-contained R script for a four-OTU tree (star or resolved), in addition to another R script assuming a constant rate over sites. These R scripts should be useful for teaching and exploring likelihood methods in phylogenetics.

bioinformatics↗

bioRxiv2018

Comprehensive proteomic and metabolomic profiling of mcr-1 mediated colistin resistance in Escherichia coli

The spread of mcr-1 in human and veterinary medicine has jeopardized the use of polymyxins, the last-resort antibiotics against life-threatening multidrug-resistant Gram-negative bacteria. As a lipid-modified gene, whether mcr-1 brings proteomic and metabolomic changes in the bacteria and affects the corresponding metabolic pathway is largely unknown. Herein, we used label-free quantitative proteomics and untargeted metabolomics to profile comprehensive proteome and metabolome characteristics of mcr-1-mediated colistin-resistant and -sensitive Escherichia coli and further insight the resistant mechanism of colistin. We identified large sets of differential expression proteins and metabolites that contributed to mcr-1-mediated antibiotic resistance predominantly in the different growth conditions with and without colistin. mcr-1 could cause the down-regulated expression of most proteins to adapt drug pressure. Pathway analysis showed that metabolic process was significantly affected, mainly related to glycerophospholipid metabolism, thiamine metabolism, and lipopolysaccharide biosynthesis. The substrate phosphatidylethanolamine for mcr-1 to mediate colistin resistance is accumulated in colistin-resistant E. coli. Notably, mcr-1 can not only cause the phosphoethanolamine modification of bacterial cell membrane lipid A, but also affect the biosynthesis and transport of lipoprotein in colistin resistance through disturbing the expression of efflux pump proteins involved in cationic antibacterial peptide resistance pathway. Overall, the disturbed glycerophospholipid metabolism, lipopolysaccharide biosynthesis and the accumulation of the substrate phosphatidylethanolamine is closely related with mcr-1-mediated colistin resistance and these findings can further provide valuable information to inhibit colistin resistance by blocking this metabolic process.

pharmacology and toxicology↗

bioRxiv2018

Wheat avenin-like protein and its significant Fusarium Head Blight resistant functions

Wheat Avenin-like proteins (TaALP) are atypical storage proteins belonging to the Prolamin superfamily. Previous studies on ALPs have focused on the proteins positive effects on dough strength, whilst no correlation has been made between TaALPs and the plant immune system. Here, we performed genome-wide characterization of ALP encoding genes in bread wheat. In silico analyses indicated the presence of critical peptides in TaALPs that are active in the plant immune system. Pathogenesis-related nucleotide motifs were also identified in the putative promoter regions of TaALP encoding genes. RT-PCR was performed on TaALP and previously characterised pathogenesis resistance genes in developing wheat caryopses under control and Fusarium graminearum infection conditions. The results showed that TaALP and NMT genes were upregulated upon F. graminearum inoculation. mRNA insitu hybridization showed that TaALP genes were expressed in the embryo, aleurone and sub-aleurone layer cells. Seven TaALP genes were cloned for the expression of recombinant proteins in Escherichia coli, which displayed significant inhibitory function on F. graminearum under anti-fungal tests. In addition, FHB index association analyses showed that allelic variations of two ALP genes on chromosome 7A were significantly correlated with FHB symptoms. Over-expression of an ALP gene on chromosome 7A showed an enhanced resistance to FHB. Yeast two Hybridization results revealed that ALPs have potential proteases inhibiting effect on metacaspases and beta-glucosidases. A vital infection process related pathogen protein, F. graminearum Beta-glucosidase was found to interact with ALPs. Our study is the first to report a class of wheat storage protein or gluten protein with biochemical functions. Due to its abundance in the grain and the important multi-functions, the results obtained in the current study are expected to have a significant impact on wheat research and industry.

molecular biology↗

bioRxiv2018

The wheat Sr22, Sr33, Sr35 and Sr45 genes confer resistance against stem rust in barley

In the last 20 years, stem rust caused by the fungus Puccinia graminis f. sp. tritici (Pgt), has re-emerged as a major threat to wheat and barley cultivation in Africa and Europe. In contrast to wheat with 82 designated stem rust (Sr) resistance genes, barleys genetic variation for stem rust resistance is very narrow with only seven resistance genes genetically identified. Of these, only one locus consisting of two genes is effective against Ug99, a strain of Pgt which emerged in Uganda in 1999 and has since spread to much of East Africa and parts of the Middle East. The objective of this study was to assess the functionality, in barley, of cloned wheat Sr genes effective against Ug99. Sr22, Sr33, Sr35 and Sr45 were transformed into barley cv. Golden Promise using Agrobacterium-mediated transformation. All four genes were found to confer effective stem rust resistance. The barley transgenics remained susceptible to the barley leaf rust pathogen Puccinia hordei, indicating that the resistance conferred by these wheat Sr genes was specific for Pgt. Cloned Sr genes from wheat are therefore a potential source of resistance against wheat stem rust in barley.

plant biology↗