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A genome-wide association analysis identified diverse loci for seedling and adult plant resistance to leaf rust and stripe rust. KASP markers were developed and validated for marker-assisted selection. Wheat leaf rust and stripe rust cause significant losses in many wheat producing regions worldwide. The objective of this study was to identify chromosome regions conferring resistance to both leaf rust and stripe rust at the seedling and adult plant stages. A diversity panel of 268 wheat lines, including 207 accessions from different wheat growing regions in China, and 61 accessions from foreign countries, were evaluated for leaf rust response at seedling stage using eight Chinese Puccinia triticina pathotypes, and also tested for leaf rust and stripe rust at adult plant stage in multiple field environments. The panel was genotyped with the Wheat 90 K Illumina iSelect SNP array. Genome-wide association mapping (GWAS) was performed using the mixed linear model (MLM). Twenty-two resistance loci including the known Lr genes, Lr1, Lr26, Lr3ka, LrZH22, and 18 potentially new loci were identified associated with seedling resistance, explaining 4.6 to 25.2% of the phenotypic variance. Twenty-two and 23 adult plant resistance (APR) QTL associated with leaf and stripe rust, respectively, were identified at adult stage, explaining 4.2–11.5% and 4.4–9.7% of the phenotypic variance. Among them, QLr-2BS was the potentially most valuable all-stage resistance gene. Seven and six consistent APR QTL were identified in multiple environments including best linear unbiased prediction (BLUP) data, respectively. Comparison with previously mapped resistance loci indicated that three of the seven leaf rust resistance APR QTL, and two of the six stripe rust resistance APR QTL were new. Four potentially pleiotropic APR QTL, including Lr46/Yr29, QLr-2AL.1/QYr-2AL.1, QLr-2AL.2/QYr-2AL.2, and QLr-5BL/QYr-5BL.1, were identified. Twelve associated SNPs were converted into kompetitive allele-specific PCR (KASP) markers and verified in bi-parental populations. The study reports genetic loci conferring resistance to both diseases, and the closely linked markers should be applicable for marker-assisted wheat breeding.

As one of the largest protein families in plants, F-box proteins are involved in many important cellular processes. Until now, a limited number of investigations have been conducted on wheat F-box genes due to its variable structure and large and polyploid genome. Classification, identification, structural analysis, evolutionary relationship, and chromosomal distribution of some wheat F-box genes are described in the present study. A total number of 1013 potential F-box proteins which are encoded by 409 genes was identified in wheat, and classified into 12 subfamilies based on their C-terminal domain structures. Furthermore, proteins with identical or similar C-terminal domain were clustered together. Location of 409 F-box genes was identified on all 21 wheat chromosomes but showed an uneven distribution. Segmental duplication was the main reason for the increase in the number of wheat F-box genes. Gene expression analysis based on digital PCR showed that most of the F-box genes were highly expressed in the later development stages of wheat, including the formation of spike, grain, flag leaf, and participated in drought stress (DS), heat stress (HS), and their combination (HD). Of the nine F-box genes we investigated using quantitative PCR (qPCR) following fungal pathogen infection, five were involved in wheat resistance to the infection by leaf rust pathogen and one in the susceptible response. These results provide important information on wheat F-box proteins for further functional studies, especially the proteins that played roles in response to heat and drought stresses and leaf rust pathogen infection.

In Arabidopsis, both pathogen invasion and benzothiadiazole (BTH) treatment activate the nonexpresser of pathogenesis-related genes 1 (NPR1)-mediated systemic acquired resistance, which provides broad-spectrum disease resistance to secondary pathogen infection. However, the BTH-induced resistance in Triticeae crops of wheat and barley seems to be accomplished through an NPR1-independent pathway. In the current investigation, we applied transcriptome analysis on barley transgenic lines overexpressing wheat wNPR1 (wNPR1-OE) and knocking down barley HvNPR1 (HvNPR1-Kd) to reveal the role of NPR1 during the BTH-induced resistance. Most of the previously designated barley chemical-induced (BCI) genes were upregulated in an NPR1-independent manner, whereas the expression levels of several pathogenesis-related (PR) genes were elevated upon BTH treatment only in wNPR1-OE. Two barley WRKY transcription factors, HvWRKY6 and HvWRKY70, were predicted and further validated as key regulators shared by the BTH-induced resistance and the NPR1-mediated acquired resistance. Wheat transgenic lines overexpressing HvWRKY6 and HvWRKY70 showed different degrees of enhanced resistance to Puccinia striiformis f. sp. tritici pathotype CYR32 and Blumeria graminis f. sp. tritici pathotype E20. In conclusion, the transcriptional changes of BTH-induced resistance in barley were initially profiled, and the identified key regulators would be valuable resources for the genetic improvement of broad-spectrum disease resistance in wheat. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

F-box proteins play critical roles in plant responses to biotic/abiotic stresses. In the present study, a total of 68 wheat F-box/Kelch (TaFBK) gene sequences encoding for 74 proteins were obtained in a genome-wide survey against EnsemblPlants. The 74 TaFBK proteins were divided into 5 categories based on their domain structures. The FBK proteins from wheat, Arabidopsis, and three other cereal species were grouped into 7 clades, and the number of Kelch domains present was their key clustering criterion. Sixty-eight TaFBK genes were unevenly distributed on 21 chromosomes. Most of TaFBKs were predicted to localize in the nucleus and cytoplasm. In silico analysis of a digital PCR revealed that TaFBKs were expressed at multiple developmental stages and tissues, and in response to drought and/or heat stresses. The TaFBK19 gene, a homologous to the Attenuated Far-Red Response (AFR) genes in other plant species, and hence named TaAFR, was selected for further analysis. The gene was isolated from the wheat line TcLr15 and its expression evaluated by quantitative real-time PCR. TaAFR transcripts were primarily detected in wheat leaves, and its expression was found to be regulated by various abiotic and biotic stresses as well as plant signaling hormones. Of particular interest, TaAFR expression was differentially regulated in the compatible vs incompatible wheat leaf rust reaction. Subcellular localization studies showed that TaAFR accumulates in the nucleus and cytoplasm. Three TaAFR-interacting proteins were identified experimentally: Skp1/ASK1-like protein (Skp1), ADP-ribosylation factor 2-like isoform X1 (ARL2) and phenylalanine ammonia-lyase (PAL). Further analysis revealed that the Skp1 protein interacted specifically with the F-box domain of TaAFR, while ARL2 and PAL were recognized by the Kelch domain. The data presented herein provides a solid foundation from which the function and metabolic network of TaAFR and other wheat FBKs can be further explored.

Six different fermented vegetables were collected from Zhejiang Province, China, to explore the associated bacterial community using a high-throughput sequencing platform. A total of 24 phyla, 274 families and 569 genera were identified from 6 samples. Firmicutes and Proteobacteria were the main phyla in all of the samples. Brevibacterium was the major genus in Xiaoshan pickled radish. Lactobacillus-related genera and Vibrio were the major genera in fermented potherb mustard and its brine. Enterobacter and Cobetia were the major genera in fermented radish and its brine. Chromohalobacter was the major genus in the tuber mustard. These results indicated clear differences were there between the bacterial genera present in Xiaoshan pickled radish, fermented potherb mustard, fermented radish, and tuber mustard. This demonstrated the possible influences of raw materials and manufacturing processes. Furthermore, a large number of lactic acid bacteria were isolated and identified by culture-dependent and 16S rRNA gene sequence analysis, which accounted for more than 68% of all the isolates. In addition, whole-genome analysis of Levilactobacillus suantsaii, Latilactobacillus sakei subsp. sakei, and Weissella cibaria showed that they had large numbers of genes associated with carbohydrate metabolism. This may explain why these three bacterial strains can grow in fermented vegetable environments.

NPR1 is a key regulator of systemic acquired resistance (SAR) in plant species. In our previous study, we identified a conserved fungal effector PNPi from Puccinia striiformis f. sp. tritici (Pst) that can suppress acquired resistance in local leaf by directly targeting the wheat NPR1 protein. In this investigation, we identified and validated a novel protein interaction between PNPi and wheat pathogenesis-related TaPR1a in the apoplastic space. TaPR1a-overexpressing wheat lines exhibited enhanced resistance to both Pst and Puccinia triticina (Pt). We further determined that exogenous expression of PNPi RNA in transgenic wheat lines reduced the degree of acquired resistance to Magnaporthe oryzae isolate P131 in the region adjacent to Pseudomonas syringae pv. tomato DC3000 infection area. Additionally, when PNPi was overexpressed, the expression levels of two plant defense responsive genes were suppressed upon P. syringae DC3000 infection in the local infiltration region. These findings established the mechanism of a single rust effector that can suppress multiple defense responses in wheat plants by targeting different components.

Rust fungi secrete various specialized effectors into host cells to manipulate the plant defense response. Conserved motifs, including RXLR, LFLAK-HVLVxxP (CRN), Y/F/WxC, CFEM, LysM, EAR, [SG]-P-C-[KR]-P, DPBB_1 (PNPi), and ToxA, have been identified in various oomycete and fungal effectors and are reported to be crucial for effector translocation or function. However, little is known about potential effectors containing any of these conserved motifs in the wheat leaf rust fungus (Puccinia triticina, Pt). In this study, sequencing was performed on RNA samples collected from the germ tubes (GT) of uredospores of an epidemic Pt pathotype PHTT(P) and Pt-infected leaves of a susceptible wheat cultivar “Chinese Spring” at 4, 6, and 8 days post-inoculation (dpi). The assembled transcriptome data were compared to the reference genome of “Pt 1-1 BBBD Race 1.” A total of 17,976 genes, including 2,284 “novel” transcripts, were annotated. Among all these genes, we identified 3,149 upregulated genes upon Pt infection at all time points compared to GT, whereas 1,613 genes were more highly expressed in GT. A total of 464 secreted proteins were encoded by those upregulated genes, with 79 of them also predicted as possible effectors by EffectorP. Using hmmsearch and Regex, we identified 719 RXLR-like, 19 PNPi-like, 19 CRN-like, 138 Y/F/WxC, and 9 CFEM effector candidates from the deduced protein database including data based on the “Pt 1-1 BBBD Race 1” genome and the transcriptome data collected here. Four of the PNPi-like effector candidates with DPBB_1 conserved domain showed physical interactions with wheat NPR1 protein in yeast two-hybrid assay. Nine Y/F/WxC and seven CFEM effector candidates were transiently expressed in Nicotiana benthamiana. None of these effector candidates showed induction or suppression of cell death triggered by BAX protein, but the expression of one CFEM effector candidate, PTTG_08198, accelerated the progress of cell death and promoted the accumulation of reactive oxygen species (ROS). In conclusion, we profiled genes associated with the infection process of the Pt pathotype PHTT(P). The identified effector candidates with conserved motifs will help guide the investigation of virulent mechanisms of leaf rust fungus.

In Arabidopsis, systemic acquired resistance (SAR) is established beyond the initial infection by a pathogen or is directly induced by treatment with salicylic acid (SA) or its functional analogs, 2,6-dichloroisonicotinic acid (INA) and benzothiadiazole (BTH). NPR1 protein is considered the master regulator of SAR in both SA signal sensing and transduction. In wheat (Triticum aestivum) and barley (Hordeum vulgare), both pathogen infection and BTH treatment can induce broad-spectrum resistance to various diseases, including powdery mildew, leaf rust, Fusarium head blight, etc. However, three different types of SAR-like responses including acquired resistance (AR), systemic immunity (SI), and BTH-induced resistance (BIR) seem to be achieved by activating different gene pathways. Recent research on wheat and barley NPR1 homologs in AR and SI has provided the initial clue for understanding the mechanism of SAR in these two plant species. In this review, the specific features of AR, SI, and BIR in wheat and barley were summarized and compared with that of SAR in model plants of Arabidopsis and rice. Research updates on downstream genes of SAR, including pathogenesis-related (PR) and BTH-induced genes, were highlighted.

Wheat leaf rust, caused by Puccinia triticina, is a commonly occurring disease in wheat growing areas of the world. Research on the virulence and genetic diversity of P. triticina will be helpful for a better understanding of the evolution tendencies and subsequently for controlling this disease. In this study, 59 isolates of P. triticina collected from Hebei Province of China in 2008 and 2010 were analyzed for virulence diversity based on 37 near-isogenic Thatcher wheat lines at seedling stage, and genetic diversity using 21 pairs of EST-SSR primers. The predominant virulence phenotypes were PHTT, THTT, and THJT in 2008, while THTS, THSS, THTT, and THST were most common in Hebei province in 2010. Clustering analysis based on the virulence and EST-SSR data revealed a high diversity of P. triticina, and differences between the populations of 2008 and 2010. There was no significant correlation between the molecular and virulence data. Genetic parameters analysis also showed high diversity of the P. triticina population in Hebei province. Nei’s gene diversity index (H) and Shannon’s information index (I) showed that the genetic diversity of population 2008 was higher than 2010. The AMOVA analysis suggested that genetic variation mainly from intra-population (61.11%).

Wheat leaf rust caused by Puccinia triticina (Pt) is one of the most severe fungal diseases threatening the global wheat production. The use of leaf rust resistance (Lr) genes in wheat breeding programs is the major solution to solve this issue. Wheat isogenic line carrying the Lr39/41 gene has shown a moderate to high resistance to most of the Pt pathotypes detected in China. In the present study, a typical hypersensitive response (HR) was observed using microscopy in leaves of the Lr39/41 isogenic line inoculated with the avirulent Pt pathotype THTT from 48 h-post inoculation. Two Lr39/41 resistance-associated suppression subtractive hybridization (SSH) libraries with a total of 6000 clones were established. Microarray hybridizations were performed on all obtained SSH clones using RNAs extracted from leaves of the Pt-inoculated and non-inoculated Lr39/41 isogenic lines, and leaves of the Pt-inoculated and non-inoculated Thatcher susceptible lines. Differentially expressed clones were analyzed by significance analysis of microarrays (SAM), followed by further sequencing. A total of 36 Lr39/41-resistance-related differentially expressed genes (DEGs) were identified, many of which had been previously reported to be involved in the plant defense response. The expression levels of eight selected DEGs during different stages of the Lr39/41-mediated resistance were further quantified by a qRT-PCR assay. Several pathogenesis-related (PR) and HR-related genes seem to be crucial for the Lr39/41-mediated resistance. In general, a brief profile of DEGs associated with the Lr39/41-mediated wheat resistance to Pt was drafted.

Background: Wheat leaf rust is an important disease worldwide. Understanding the Puccinia triticina f.sp tritici (Pt) pathogenic molecular mechanism and inconstant toxic region are highly important for managing the disease. The present study aimed to analyze pathogenic divergences between Pt isolates. Results: Total RNA was extracted from Thatcher infected by two Pt isolates, Tc361_1 (THTT) and Tc284_2 (THTS) at 144 hours post inoculation (hpi). The mRNA then was harvested and sequenced. Results indicated that a total of 2,784 differential expressed genes (DEGs) were detected. Forty-five genes were specifically expressed in THTT including transcription initiation factor, transmembrane transporter activity and so on, while 26 genes were specially expressed in THTS including GTPase activity, ABC transporter and so on. Fifty-four differential expressed candidate effectors were screened from the tow isolates. Two candidate effectors were chosen and validated on tabacco, and the result showed that they can inhibit the necrosis induced by Bax. qRT-PCR of 12 significantly different expressed genes were carried out to prove that the results of RNA-seq is similar to that of qRT-PCR at 144 hpi and show their expression level in the early stage and the difference between two Pt pathotypes.Conclusion: The results obtained in this study showed that the transcript profiles between THTT or THTS and Thatcher were very complicated.

Puccinia triticina (Pt), the causal agent of wheat leaf rust, is one of the most destructive fungal pathogens threatening global wheat cultivations. The rational utilization of leaf rust resistance (Lr) genes is still the most efficient method for the control of such diseases. The Lr47 gene introgressed from chromosome 7S of Aegilops speltoides still showed high resistance to the majority of Pt races collected in China. However, the Lr47 gene has not been cloned yet, and the regulatory network of the Lr47-mediated resistance has not been explored. In the present investigation, transcriptome analysis was applied on RNA samples from three different wheat lines (&ldquo, Yecora Rojo&rdquo, &ldquo, UC1037&rdquo, and &ldquo, White Yecora&rdquo, ) carrying the Lr47 gene three days post-inoculation with the epidemic Pt race THTT. A comparison between Pt-inoculated and water-inoculated &ldquo, Lr47-Yecora Rojo&rdquo, lines revealed a total number of 863 upregulated (q-value &lt, 0.05 and log2foldchange &gt, 1) and 418 downregulated (q-value &lt, 0.05 and log2foldchange &lt, &minus, 1) genes. Specifically, differentially expressed genes (DEGs) located on chromosomes 7AS, 7BS, and 7DS were identified, ten of which encoded receptor-like kinases (RLKs). The expression patterns of these RLK genes were further determined by a time-scale qRT-PCR assay. Moreover, heatmaps for the expression profiles of pathogenesis-related (PR) genes and several transcription factor gene families were generated. Using a transcriptomic approach, we initially profiled the transcriptional changes associated with the Lr47-mediated resistance. The identified DEGs, particularly those genes encoding RLKs, might serve as valuable genetic resources for the improvement of wheat resistance to Pt.

The purpose of the present study was to identify the potential targets and markers for diagnosis, therapy and prognosis in patients with prolactinoma at the molecular level and to determine the therapeutic effects of genipin in prolactinoma. The gene expression profiles of GSE2175, GSE26966 and GSE36314 were obtained from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) were identified after comparing between gene expression profiles of the prolactinoma tissues and normal tissues. Then, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and protein‑protein interaction (PPI) network analysis were conducted. In addition, in vitro, scratch assay, colony‑forming assay, Cell Counting Kit 8 (CCK8) assay and flow cytometry were performed to verify the functional effects of genipin. An aggregate of 12,695, 3,847 and 5,310 DEGs were identified from GSE2175, GSE26966 and GSE36314, respectively. The results of GO and KEGG analysis showed that the DEGs significant and important for prolactinoma were mostly involved with 'spindle pole' and 'oocyte meiosis'. A total of 20 genes were selected as hub genes with high degrees after PPI network analysis, including mitogen‑activated protein kinase 1 (MAPK1), MYC, early growth response 1 (EGR1), Bcl2 and calmodulin 1 (CALM1). CCK8 assay, colony‑forming assay and scratch assay were performed to verify the anti‑prolactinoma effect of genipin. The results of flow cytometry showed that apoptosis was increased by genipin. MAPK1, MYC, EGR1, Bcl2 and CALM1 were screened as main hub genes. Genipin upregulated the expression level of EGR1 and p21 (downstream mediator of EGR1) and EGR1, inhibited the proliferation and migration of prolactinoma cells. Genipin is a promising drug for treatment of patients with prolactinoma.

Background Wheat leaf rust is an important disease worldwide. Understanding the pathogenic molecular mechanism of Puccinia triticina Eriks. (Pt) and the inconstant toxic region is critical for managing the disease. The present study aimed to analyze the pathogenic divergence between Pt isolates. Results Total RNA was extracted from the wheat cultivar Thatcher infected by two Pt isolates, Tc361_1 (THTT) and Tc284_2 (THTS), at 144 h post inoculation (hpi). The mRNA was then sequenced, and a total of 2784 differentially expressed genes (DEGs) were detected. Forty-five genes were specifically expressed in THTT; these genes included transcription initiation factors and genes with transmembrane transporter activity and other genes. Twenty-six genes were specifically expressed in THTS, including genes with GTPase activity, ABC transporters and other genes. Fifty-four differentially expressed candidate effectors were screened from the two isolates. Two candidate effectors were chosen and validated on tobacco, and the results showed that they could inhibit necrosis induced by BAX. qRT-PCR of 12 significant DEGs was carried out to validate that the results are similar to those of RNA-seq at 144 hpi, to show the expression levels of these DEGs in the early stage and to elucidate the differences in expression between the two Pt pathotypes. Conclusion The results obtained in this study showed that although the two pathotypes of THTT and THTS contribute similar virulence to wheat, there are a large number of genes participate in the interaction with the susceptible wheat cultivar Thatcher, and revealed the pathogenicity of rust is very complicated.

Leaf rust (LR) is a destructive foliar disease of common wheat (Triticum aestivum L.) worldwide. Growing resistant cultivars with adult plant resistance (APR) are the ideal way to control the disease. The aim of the present study was to map quantitative trait loci (QTL) for leaf rust resistance using 137 doubled-haploid (DH) lines derived from the Pingyuan 50 × Mingxian 169 cross. The same population was previously tested for stripe rust (YR) and powdery mildew (PM) response, and the data were reassessed to determine the presence of QTL with pleiotropic effects. Phenotyping for leaf rust response was conducted in six environments at Baoding in Hebei province and Zhoukou in Henan province. The DH lines were genotyped using the wheat 55K SNP array and additional SSR markers. Eight QTLs for LR resistance were identified in the present study using the inclusive composite interval mapping (ICIM). The flanking sequences of all the SNP probes were subjected to BLAST against the Chinese Spring reference sequence to determine physical positions. Six LR resistance loci were contributed by Pingyuan 50, but QLr.hebau-2DS2 and QLr.hebau-3AL were from Mingxian 169. QLr.hebau-3DS, a new and stable QTL detected in all environments, explained 4.2–20.0% of the phenotypic variation. Another new QTL, QLr.hebau-3AL detected in four environments had a PVE (phenotypic variance explained) of 5.7–10.1%. QLr.hebau-1BL, QLr.hebau-2DS2, and QLr.hebau-7DL are new loci. Two QTLs showed potential pleiotropic effects on disease response. QTL on chromosome 7DL might be pleiotropic to LR and PM, and the QTL on 5DL might confer pleiotropic resistance to LR and YR. Kompetitive allele-specific PCR (KASP) markers for QLr.hebau-3AL and QLr.hebau-3DS were successfully developed and validated. The QTL identified with their flanking markers and in the present study could be useful for fine mapping, candidate gene mining, and marker-assisted selection (MAS).

F-box proteins constitute one of the largest protein families and play many important roles in plant. To date, less is known about functions of wheat F-box protein. A Kelch-type F-box gene TaFBK was isolated from wheat TcLr15. TaFBK transcripts were more abundant in pistil and leaf tissues, and accumulated more in the susceptible combination than that in the resistant one. The treatment of SA, MeJA, NaCl and PEG caused a slight up-regulation of TaFBK. GFP localization studies showed that TaFBK accumulated in the nucleus and cytoplasm. Moreover, TaFBK bound TaSkp1 by the F-box domain and recognized TaSLY1 via the Kelch domain.

Wheat cultivar Een1, 34 near isogenic lines (NILs), and two cultivars were used as plant materials to evaluate the resistance of Een1 to leaf rust disease. Infection type identification and gene postulation were carried out by inoculation of 12 Chinese Puccinia triticina (Pt) pathotypes. Based on the unique phenotype of Een1, we speculated that Een1 might carry Lr gene(s) different from the tested ones. The chromosomal locations for resistance gene to leaf rust disease was employed using SSR primers mapping the populations derived from the cross between Een1 and susceptible Thatcher. A total of 285 plants in the F2 population were tested by inoculating Pt pathotype FHNQ during the seedling stage. Results from the segregation analysis fits a ratio of 3:1 (${\chi }_{3:1}^{2}=2.37$, P = 0.12), indicating the presence of a single dominant gene in Een1 conferring resistance to FHNQ. A total of 1,255 simple sequence repeat (SSR) primers were first used to identify the likely linked markers based on bulk segregation analysis (BSA), and then those likely linked markers were further genotyped in the F2 population for linkage analysis. Our linkage analysis found that the resistance gene (LrE1) was distal to seven SSR loci on the long arm of chromosome 7B, with distances from 2.6 cM (Xgwm344) to 27.1 cM (Xgwm131). The closest marker Xgwm344 was further verified with F3 lines.

Systemic acquired resistance (SAR) in Arabidopsis is established beyond the initial pathogenic infection or is directly induced by treatment with salicylic acid or its functional analogs (SA/INA/BTH). NPR1 protein and WRKY transcription factors are considered the master regulators of SAR. Our previous study showed that NPR1 homologs in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) regulated the expression of genes encoding pathogenesis-related (PR) proteins during acquired resistance (AR) triggered by Pseudomonas syringae pv. tomato DC3000. In the present examination, AR induced by P. syringae DC3000 was also found to effectively improve wheat resistance to Puccinia triticina (Pt). However, with more complex genomes, genes associated with this SAR-like response in wheat and barley are largely unknown and no specific WRKYs has been reported to be involved in this biological process. In our subsequent analysis, barley transgenic line overexpressing wheat wNPR1 (wNPR1-OE) showed enhanced resistance to Magnaporthe oryzae isolate Guy11, whereas AR to Guy11 was suppressed in a barley transgenic line with knocked-down barley HvNPR1 (HvNPR1-Kd). We performed RNA-seq to reveal the genes that were differentially expressed among these transgenic lines and the wild-type barley plants during the AR. Several PR and BTH-induced (BCI) genes were designated as downstream genes of NPR1. The expression of few WRKYs was significantly associated with NPR1 expression during the AR events. The transient expression of three WRKY genes, including HvWRKY6, HvWRKY40, and HvWRKY70, in wheat leaves by Agrobacterium-mediated infiltration enhanced the resistance to Pt. In conclusion, a profile of genes associated with NPR1-mediated AR in barley was drafted and WRKYs discovered in the current study showed a substantial potential for improving wheat resistance to Pt.

β-1,3-glucanases represent a group of pathogenesis-related proteins (PRs) that have been extensively reported to be involved in plant defense response towards fungal pathogens infection. However, it remains unknown how these genes are involved in wheat against leaf rust pathogen Puccinia triticina. Here, we present the cloning and expression analysis of a full length β-1,3-glucanase gene, TcLr19Glu, from the near isogenic wheat line TcLr19 infected by leaf rust pathogen. TcLr19Glu encodes a 342 amino acid protein with deduced molecular weight of 34.86 kDa that contains a conserved glycoside hydrolase family 17 domain widely existing in β-1,3-glucanases family. The expression profile of TcLr19Glu detected by quantitative real-time PCR showed that the transcript was induced by P. triticina both in the compatible and incompatible interactions, but the accumulation level of transcript was statistically significant in the incompatible interaction compared with that in the compatible interaction. Subsequently, we demonstrated that the accumulation of TcLr19Glu transcript significantly differentiates in tested wheat organs and TcLr19Glu was noticeably induced by the signaling molecules including abscisic acid (ABA) and salicylic acid (SA). Furthermore, induction and quantification of TcLr19Glu protein in compatible and incompatible interactions was measured and the amount of protein was higher in the incompatible interaction than compatible interaction. All these results allow us to conclude that TcLr19Glu is involved in the Lr19-mediated defense response against rust pathogen.

The Chinese wheat line Yu 356-9 exhibits a high level of resistance to leaf rust. In order to decipher the genetic base of resistance in Yu 356-9, gene postulation, inheritance analyses, and chromosome linkage mapping were carried out. Gene postulation completed using 15 leaf rust pathotypes and 36 isogenic lines indicated that Yu 356-9 was resistant to all pathotypes tested. F 1 and F 2 plants from the cross Yu 356-9 (resistant)/Zhengzhou 5389 (susceptible) were tested with leaf rust pathotype “FHNQ” in the greenhouse. Results indicated a 3:1 segregation ratio, indicative of the presence of a single dominant leaf rust resistance gene in Yu 356-9 which was temporarily designated as LrYu. Bulk segregant analysis and molecular marker assays were used to map LrYu. Five simple sequence repeat (SSR) markers on chromosome 2BS were found closely linked to LrYu. Among these markers, Xwmc770 is the most closely linked, with a genetic distance of 5.7 cM.

Leaf rust, caused by Puccinia triticina, is an important foliar disease of wheat (Triticum aestivum L.) worldwide. In the present study, CIMMYT line 19HRWSN-122 and 36 lines with known Lr (leaf rust resistance) genes were inoculated with 13 Chinese P. triticina pathotypes for postulation of Lr genes at the seedling stage. Line 19HRWSN-122 showed high resistance to all 13 P. triticina pathotypes in the greenhouse, indicating that it carries effective seedling resistance. This may be due to a resistance gene combination, an effective gene to all pathotypes present in China or a new resistance gene. With the objective of mapping the putatively new gene for resistance to leaf rust, 20 F1, 280 F2 plants and 254 F2:3 lines from the cross 19HRWSN-122 × Zhengzhou 5389 (susceptible) were inoculated with P. triticina pathotype THJP in the greenhouse. Results based on the F1, F2 and F2:3 lines indicated that a single dominant gene, temporarily designated LrHR122, was present in 19HRWSN-122. Bulked segregant analysis was performed on equal amounts of genomic DNA from ten resistant and ten susceptible F2:3 lines. Molecular markers polymorphic between the resistant and susceptible bulks were used to genotype F2:3 lines. LrHR122 was linked to one SSR marker, one STS marker, one SCAR marker and three EST markers on chromosome 3DL. Marker SCS1302 609 co-segregated with LrHR122, and the closest flanking markers were BE442875 and STS24-16 at genetic distances of 0.4 and 0.4 cM, respectively. Lr24 is known to be located on chromosome 3DL near LrHR122. In seedling tests, lines with both LrHR122 and Lr24 showed high resistance to all 13 Chinese P. triticina pathotypes. According to the pedigree and chromosome position LrHR122 should be Lr24. Lr24 was closely linked to one SSR marker and three EST markers in the terminal region of 3DL. These markers should be useful for marker assisted selection in breeding leaf rust resistant wheat cultivars.

Leaf rust (LR), caused by Puccinia triticina , is one of the most widespread diseases of common wheat ( Triticum aestivum L.) worldwide. The LR resistance gene LrBi16 has been mapped on chromosome arm 7BL in Chinese wheat cultivar Bimai 16 and was closely linked to SSR loci Xcfa2257 and Xgwm344 with genetic distances of 2.8 cM and 2.9 cM, respectively. In the present study, a total of 304 AFLP primer pairs were used to screen Bimai 16 and Thatcher and resistant and susceptible DNA bulks. The polymorphic AFLP marker P-ATT/M-CGC 173 bp was used to genotype F 2 and F 3 populations to identify markers more closely linked to LrBi16 . Marker P-ATT/M-CGC 173 bp was tightly linked to LrBi16 with a genetic distance of 0.5 cM. As LrBi16 was mapped near the Lr14a locus, 809 F 2 plants from the Bimai 16/RL6013 ( Lr14a ) cross were inoculated with the Pt pathotype FHNQ to test the allelism of Lr14a and LrBi16 . All of the F 2 plants were resistant to FHNQ (IT between; and 2), suggesting that Lr14a and LrBi16 are allelic.

The wheat ( Triticum aestivum L.) line 5R618, bred at the China Agricultural University, is resistant in the seedling stage to the majority of the current Chinese pathotypes of wheat leaf rust ( Puccinia triticina ). To identify and map the leaf rust resistance gene in the 5R618 line, F 2 plants and F 2:3 families from a cross between 5R618 and Zhengzhou5389 (susceptible) were inoculated in the greenhouse with the Chinese P. triticina pathotype THJP. Results from the F 2 and F 2:3 populations indicate that a single dominant gene, temporarily designated Lr5R , conferred resistance. Using the molecular marker method, Lr5R was located on the 3DL chromosome. It was closely linked to the markers Xbarc71 and OPJ-09 with genetic distances of 0.9 cM and 1.0 cM, respectively. At present only one designated gene ( Lr24 ) is located on the 3DL chromosome. The genetic distance between Lr5R and Lr24 confirms that Lr5R is a new leaf rust resistance gene.

Leaf rust, caused by Puccinia triticina, is one of the major wheat diseases worldwide and poses a constant threat to common wheat (Triticum aestivum L.) production and food security. Results from the F2 and F2:3 populations derived from a cross between resistant line Fundulea 900 and susceptible cultivar Thatcher indicated that a single dominant gene, tentatively designated LrFun, conferred resistance to leaf rust. In order to identify other possible genes in Fundulea 900, nine P. triticina pathotypes avirulent on Fundulea 900 were used to inoculate F2:3 families. The results showed that at least two leaf rust resistance genes were present in Fundulea 900. A total of 1,706 pairs of simple sequence repeat (SSR) primers were used to test the parents and resistant and susceptible bulks. Eight polymorphic markers from chromosome 7BL were used for genotyping the F2 and F2:3 populations. LrFun was linked to eight SSR loci on chromosome 7BL. The two closest flanking SSR loci were Xgwm344 and Xwmc70, with genetic distances of 4.4 and 5.7 cM, respectively. At present four leaf rust resistance genes, Lr14a, Lr14b, Lr68 and LrBi16, are located on chromosome 7BL. In a seedling test with 12 P. triticina isolates, the reaction patterns of LrFun were different from those of lines carrying Lr14a, Lr14b and LrBi16. Lr68 is an adult plant resistance gene, and it is different from the seedling resistance gene LrFun. Therefore, we concluded that LrFun is a new leaf rust resistance gene.

The hypersensitive response (HR) is one of the most-efficient forms of plant defense against biotrophic pathogens. However, the molecular mechanisms leading to HR remain largely unknown. A putative hypersensitive-induced response (HIR) protein gene TaHIR4 cDNA (919 bp) and a DNA sequence (2520 bp) including at least five exons were isolated and identified from wheat. Phylogenetic analysis showed that TaHIR4 was highly homologous to HvHIR4 from barley at both the cDNA and deduced amino-acid levels. Reverse transcription quantitative polymerase chain reaction (qRT-PCR) results showed that TaHIR4 transcripts were highly upregulated by infection of the leaf rust pathogen and expressed in all tested samples except the mature seeds. Western blotting results also showed that TaHIR4 protein was upregulated in wheat leaves infected with the leaf rust pathogen. Characterization and expression profiles at the gene and protein levels suggested that TaHIR4 plays a role in wheat HR, caused by the leaf rust pat...

To detect the leaf rust resistance genes in the 7 Chinese spring wheat clultivars Shenmian 99025, Shenmia 99042, Shenmian 85, Shenmian 91, Shenmian 96, Shenmian 1167 and Shenmian 962, Thatcher, Thatcher backgrounded near-isogenic lines and 15 pathotypes of P. triticina were used for gene postulate at the seedling stage, and 9 of the 15 pathotypes were used in the field tests. Molecular markers closely linked to, or co-segregated with resistance genes Lr1, Lr9, Lr10, Lr19, Lr20, Lr21, Lr24, Lr26, Lr28, Lr29, Lr32, Lr34, Lr35, Lr37, Lr38 , and Lr47 were screened to assist detection of the resistance genes. As results, 4 known resistance genes, including Lr1, Lr9, Lr26 , and Lr34 , and other unknown resistance genes were postulated singly or in combination in the tested cultivars. Shenmian 85, Shenmian 91, Shenmian 96, Shenmian 962, Shenmian 1167, and Shenmian 99042 are potentially useful for wheat production and breeding programs. The result suggested that combining gene postulation, molecular markers and pedigrees is effective and more accuracy method to know the resistance genes in cultivars.

Neijiang 977671 and 19 near-isogenic lines with known leaf rust resistance genes were inoculated with 12 pathotypes of Puccinia triticina for postulation of leaf rust resistance genes effective at the seedling stage. The reaction pattern of Neijiang 977671 differed from those of the lines with known leaf rust resistance genes used in the test, indicating that Neijiang 977671 may carry a new leaf rust resistance gene(s). With the objective of identifying and mapping the new gene for resistance to leaf rust, F1 and F2 plants, and F2:3 families, from Neijiang 977671 × Zhengzhou 5389 (susceptible) were inoculated with Chinese P. triticina pathotype FHNQ in the greenhouse. Results from the F2 and F2:3 populations indicated that a single dominant gene, temporarily designated LrNJ97, conferred resistance. In order to identify other possible genes in Neijiang 977671 other eight P. triticina pathotypes avirulent on Neijiang 977671 were used to inoculate 25 F2:3 families. The results showed that at least three leaf rust resistance genes were deduced in Neijiang 977671. Bulked segregant analysis was performed on equal amounts of genomic DNA from 20 resistant and 20 susceptible F2 plants. SSR markers polymorphic between the resistant and susceptible bulks were used to analyze the F2:3 families. LrNJ97 was linked to five SSR loci on chromosome 2BL. The two closest flanking SSR loci were Xwmc317 and Xbarc159 at genetic distances of 4.2 and 2.2 cM, respectively. At present two designated genes (Lr50 and Lr58) are located on chromosome 2BL. In the seedling tests, the reaction pattern of LrNJ97 was different from that of Lr50. Lr50 and Lr58 were derived from T. armeniacum and Ae. triuncialis, respectively, whereas according to the pedigree of Neijiang 977671 LrNJ97 is from common wheat. Although seeds of lines with Lr58 were not available, it was concluded that LrNJ97 is likely to be a new leaf rust resistance gene.

Hypersensitive induced reaction (HIR) protein had been reported to play roles in plant resisting biotic and abiotic stress. In this study, a full length cDNA TaHIR2 , encoding a 284- amino-acid protein with deduced MW of 31.34 kDa and predicted pI of 5.42, was cloned and identified from wheat leaves infected by leaf rust pathogen. The amino acid sequence deduced from TaHIR2 shared 99% homology with HvHIR2 from barley and contained prohibitins-domain which is a member of SPFH protein domain. Temporal expression profiles indicated that the TaHIR2 transcripts in the incompatible and compatible interactions begun to increase at 18 h post-inoculation (hpi), and reached the maximum at 36 hpi, then declined, but the relative expression of TaHIR2 transcripts in the incompatible interaction was 4.11 and 1.32 times higher than that in compatible one at 24 and 36 hpi, respectively. The accumulation of TaHIR2 transcript was the highest in wheat leaf. Furthermore, Western blot showed that the maximum accumulation of the TaHIR2 at the protein level occurred at 60 and 96 hpi in the incompatible and compatible interactions, respectively. Based on the above results, we primarily concluded that a novel TaHIR2 gene was successfully cloned from wheat and may play a role in wheat resistant to the leaf rust pathogen.

This research was aimed to develop AFLP markers co-segregated with gene Lr24 and validate the using for marker assisted selection (MAS). An F2 population developed from the cross between the resistant line TcLr24 and the susceptible line Thatcher was tested for resistance to the Puccinia triticina races BGQQ and SHRT using for genetic analysis and molecular marker. A total of 224 AFLP primer combinations were used to test the resistant and susceptible parents, as well as the resistant bulk and the susceptible bulk. Four AFLP markers, P-AGA/M-CTT289 bp, P-AGC/M-CAC188 bp, P-AGC/M-CAC162 bp and P-ACG/M-CGC239 bp were co-segregated with Lr24. The AFLP fragment from the primer combination P-ACG/M-CGC was cloned, sequenced and converted into a STS marker named as ASTS212. Thatcher backgrounded NILs and 115 varieties were examined by using this STS marker and the marker SCS1302607 developed by Gupta. 5R615, 5R616, 1R13, and 1R17 were identified and validated to contain gene Lr24. The marker is dominant and may be useful in identification the resistance gene Lr24 in wheat and wheat breeding programs.

Virus-induced gene silencing (VIGS) offers a rapid and high throughout technology platform for the analysis of gene function in plants. The barley stripe mosaic virus (BSMV) VIGS system was optimized in studies silencing phytoene desaturase expression in wheat, and demonstrated that infection with BSMV construct carrying a 412 bp fragment of TaRAR1 caused conversion of incompatible to compatible interactions to Lr24-mediated resistance in wheat TcLr24 and cultivar 5R615 harboring Lr24 whereas infection with a control construct had no effect on resistance or susceptibility. RT-PCR analysis showed that BSMV-induced gene silencing could be detected at mRNA levels. These studies indicated that TaRAR1 was a required component for Lr24-mediated race-specific resistance and the BSMV-VIGS was a powerful tool for dissecting the genetic pathways of disease resistance in hexaploid wheat.

To clone the antibiotic biosynthesis gene cluster of Streptomyces roseoflavus Men-myco-93-63, we constructed a Fosmid genomic library. The genomic DNA of the strain Men-myco-93-63 was isolated by the modified CTAB procedure, and the size of most genomic DNA fragments was larger than 150 kb. Then, a Fosmid genomic library containing more than 6000 clones was constructed. The average size of the inserted DNA in recombinant plasmids was 38.1 kb, and the probability of harboring any gene in the genome of the strain Men-myco-93-63 was 99.99%. The library coverage was at least a 10-fold genome equivalent. Therefore, the constructed Fosmid library meets the requirements as a standard genomic library

One resistance gene analog fragment named RGA-CIN14 was isolated from TcLr19 wheat, which contains kinase-2, kinase-3a, and the GLPL motif of the NBS-spanning region, using degenerated primers according to the nucleotide binding site (NBS) conserved domain. Based on the RGA-CIN14, a full-length cDNA, CIN14, which was 2 987 bp encoding 880 amino acids, was obtained by using the method of the rapid amplification cDNA ends (RACE). Bioinformatics analysis showed that the deduced amino acids of CIN14 protein consisted of a NB-ARC conserved domain and many leucine-rich repeats (LRR) domains. The phylogenetic tree analysis indicated a considerable identity of the protein encoded by CIN14 with that of wheat leaf rust resistance gene Lr1, but a lower similarity with Lr21. The expression profile of the CIN14 gene detected by semi-quantitative RT-PCR showed that the CIN14 gene was not induced by Puccinia triticina and it was a constitutive gene with low abundance in the wheat leaf tissue. The resistance homology sequence was successfully obtained, which provides the shortcut for cloning of the resistance gene in TcLr19 wheat.

The objective of this work was to obtain a resistance gene analog from the TcLr35 wheat line. The 5’ and 3’ ends of the resistance gene homology fragment S2A2 from TcLr35 were obtained by rapid amplification cDNA ends (RACE), and a 3476-bp full length cDNA was obtained using gene specific primers based on the spliced sequence. Its deduced 866 amino acid sequence has the characteristic NBS-LRR domains of plant resistance gene products and includes a coiled-coil (CC) region typical of monocots. The genomic DNA sequence shows the presence of three exons and two short introns upstream of the predicted stop codon. BLASTp analysis indicates a considerable identity of S2A2 with a cloned barley NBS-LRR resistance gene homology sequence and a lower similarity with wheat leaf rust resistance genes Lr1, Lr21, Lr34, and Lr10. The S2A2 gene appeared not to be induced by Puccinia triticina and was a constitutive gene with low abundance in the wheat leaf tissue by semi-quantitative RT-PCR analysis.

A chromosome walking method was improved in this work. The new method was named as nonspecific primer anchored PCR (NPA-PCR). Nested gene specific primers were designed based on the known region and long random primer using degeneracy oligonucleotides for nonspecific anchoring. Annealing temperatures were varied to control the priming. Target sequences were obtained by PCR with random primer and gene-specific primer. Nonspecific sequence with long random primers at both ends formed stem loop structure due to inverted terminal repeats. The method was employed to isolate a gene with newly-isolated actinomycin producing strain Streptomyces setonii Z-L-22. A 0.77 kb fragment of actinomycin synthetase gene cluster was isolated from the strain. The fragments of 1474bp and 701bp were obtained, respectively, at the up and down streams of known fragment through the this method. NCBI Blast analysis showed that the walking sequence and the known sequence were located conjointly in the same cluster gene. It demonstrated that the result was correct and this technique could be useful and efficient for chromosome walking or isolating the gene.

This research is aimed at developing TRAP markers, as a probe for library screening, closely linked to or co-segregated with Lr24. Ninety TRAP primer pairs were used to test the resistant and susceptible parents, as well as the resistant bulk and the susceptible bulk in our study. The polymorphic TRAP primers of TcLr24 were employed to genotype the F2 population from TcLr24×Thatcher subsequently. Ten of 90 TRAP primer pairs displayed polymorphism between TcLr24 and Thatcher, accounting for 11.11%. A further study found that primer ARBI1/RGA-2F generated a 161 bp fragment presented only in the resistance plants of F2 population. Forty-five other wheat leaf rust resistant NILs and 30 diploid materials of wheat were also tested to detect the specificity of the primer. This specific band was amplified in TcLr19, TcLr29, TcLr38, TcLr42 and TcLr44, but absented in all the 30 diploid materials. It was concluded that this marker ARBI1/RGA-2F was closely linked to Lr24, which could be used to detect Lr24 in the F2 population of TcLr24×Thatcher, and be further used as a probe for cDNA and BAC library screening of TcLr24.

Leaf rust, caused by Puccinia triticina, is one of the most widespread diseases in common wheat globally. The Chinese wheat cultivar Zhoumai 22 is highly resistant to leaf rust at the seedling and adult stages. Seedlings of Zhoumai 22 and 36 lines with known leaf rust resistance genes were inoculated with 13 P. triticina races for gene postulation. The leaf rust response of Zhoumai 22 was different from those of the single gene lines. With the objective of identifying and mapping, the new gene(s) for resistance to leaf rust, F1, F2 plants and F2:3 lines from the cross Zhoumai 22/Chinese Spring were inoculated with Chinese P. triticina race FHDQ at the seedling stage. A single dominant gene, tentatively designated LrZH22, conferred resistance. To identify other possible genes in Zhoumai 22, ten P. triticina races avirulent on Zhoumai 22 were used to inoculate 24 F2:3 lines. The same gene conferred resistance to all ten avirulent races. A total of 1300 simple sequence repeat (SSR) markers and 36 EST markers on 2BS were used to test the parents, and resistant and susceptible bulks. Resistance gene LrZH22 was mapped in the chromosome bin 2BS1-0.53-0.75 and closely linked to six SSR markers (barc183, barc55, gwm148, gwm410, gwm374 and wmc474) and two EST markers (BF202681 and BE499478) on chromosome arm 2BS. The two closest flanking SSR loci were Xbarc55 and Xgwm374 with genetic distances of 2.4 and 4.8 cM from LrZH22, respectively. Six designated genes (Lr13, Lr16, Lr23, Lr35, Lr48 and Lr73) are located on chromosome arm 2BS. In seedling tests, LrZH22 was temperature sensitive, conferring resistance at high temperatures. The reaction pattern of Zhoumai 22 was different from that of RL 4031 (Lr13), RL 6005 (Lr16) and RL 6012 (Lr23), Lr35 and Lr48 are adult-plant resistance genes, and Lr73 is not sensitive to the temperature. Therefore, LrZH22 is likely to be a new leaf rust resistance gene or allele.

Two pairs of primers were designed according to the amino acid conserved regions of reported plant disease resistance gene which encode proteins that contain nucleotide-binding site (NBS) and leucine-rich repeats (LRR). Two resistance gene analogues (RGAs) had been obtained, which were named as S2A2 and LRR1, from the RNA of TcLr35 containing Lr35 gene conferring resistance against wheat leaf rust by reverse transcription polymerase chain reaction (RT-PCR). S2A2 had 539 bp encoding 177 amino acids and LRR1 had 215 bp encoding 58 amino acids. Homology search in GenBank showed that S2A2 was 91% identical to a resistance gene homology EST sequence of barley. BLASTp analysis showed that S2A2 contained the conserved motifs of NB-ARC: P-loop, kinase 2, kinase 3a and transmembrance domain and the amino acid of LRR1 was 74% identical to Xa21. Northern hybridization showed that these RGAs expression was not induced by Puccinia triticina inoculation, indicating that they are constitutive genes with low abundance in wheat. 3'RACE-PCR was carried out with gene-specific primers and the 3'-universal primer provided in the kit. An amplified fragment of 567 bp that overlapped with the LRR1 sequence by 184 bp was obtained. A 598 bp fragment was determined to be the sequence of LRR1 except the 5'cDNA end encoding a predicted polypeptide of 153 amino acid containing three LRR repeats. The fragment also contained 84 bp untranslated region (UTR) at 3'-ends and 21 bp poly(A) tail. The study paved the way for the cloning of Lr35 or the resistance-related gene.

Amplified fragment length polymorphism (AFLP) analysis was carried out in Thatcher, near isogenic lines (NILs) carrying different genes conferring resistance against wheat leaf rust, and TcLr45×Thatcher F2 progenies were used to develop markers for Lr45 gene. Sixty AFLP primer combinations were screened and most of them provided clear amplification products, 31 primer combinations displayed polymorphism of TcLr45 in 23 NILs. Two AFLP markers closely linked to the gene Lr45 were acquired: P-AGG/M-GAG(subscript 261 bp), which was found closely linked to the Lr45 locus at a distance of 0.6 cM on one side, and P-ACA/M-GGT(subscript 105 bp), which was found at a distance of 1.3 cM on the other side. The specific bands were cloned and subsequently sequenced. The 261-bp fragment produced by P-AGG/M-GAG showed 86% similarity with the sequence of Vulgare Hort Ⅰ gene; the 105-bp fragment produced by P-ACA/M-GGT showed 96% similarity with the phosphatidylserine decarboxylase gene of the Triticum monococcum. Both included an open reading frame (ORF).

Microsatellite was carried out in Thatcher, six near-isogenic lines and F 2 progeny of TcLr19xThatcher to develop molecular markers for leaf rust resistance gene Lr19 . Thirteen primer pairs were screened, of which one primer pair Xgwm44 displayed polymorphsim in the population of TcLr19, Thatcher, and their F 2 generations. One marker closed linked to Lr19 resistance trait was obtained, and was named Xgwm44 139 bp with the genetic distance 0.9 cM. The research shows that Lr19 has more potential in marker-assisted breeding programs in wheat and provides a step stone for mapping genetic map, physical map and the eventual cloning.

Six QTL for adult plant resistance to leaf rust, including two QTL effective against additional diseases, were identified in a RIL population derived from a cross between Shanghai 3/Catbird and Naxos. Leaf rust is an important wheat disease and utilization of adult-plant resistance (APR) may be the best approach to achieve long-term protection from the disease. The CIMMYT spring wheat line Shanghai 3/Catbird (SHA3/CBRD) showed a high level of APR to Chinese Puccinia triticina pathotypes in the field. To identify APR genes in this line, a mapping population of 164 recombinant inbred lines (RILs) was developed from a cross of this line and Naxos, a moderately susceptible German cultivar. The RILs were evaluated for final disease severity (FDS) at Baoding, Hebei province, and Zhoukou, Henan province, in the 2010–2011 and 2011–2012 cropping seasons. QTL analysis detected one major QTL derived from SHA3/CBRD on chromosome 2BS explaining from 15 to 37 % of the phenotypic variance across environments. In addition one minor resistance QTL on chromosome 1AL from SHA3/CBRD and four minor QTL from Naxos on chromosomes 2DL, 5B, 7BS, and 7DS were also detected. SHA3/CBRD also possessed seedling resistance gene Lr26, and Naxos contained Lr1 based on gene postulation following tests with an array of P. triticina pathotypes and molecular marker assays. These seedling resistance and APR genes and their closely linked molecular markers are potentially useful for improving leaf rust resistance in wheat breeding programs.

Ninety-three strains of Streptomyces were isolated from lenticels of potato tubers grown in naturally disease-suppressive and disease-conducive soils. Twenty-two strains showed more antibiotic activity against virulent Streptomyces scabies RB3II than the standard pathogen-suppressive strains PonR and PonSSII. These 22 suppressive strains were non-pathogenic on leaf-bud tubers in the greenhouse. These suppressive strains plus standard strains PonR and PonSSII, 4 Minnesota (MN) virulent S. scabies strains, 11 virulent S. scabies strains, and 2 virulent Streptomyces acidiscabies strains from the eastern United States were evaluated in all possible paired combinations for antibiotic activity and competitive interactions in antibiotic and co-plating assays. A significant positive correlation between the ability of a strain to inhibit others and the ability of that strain to resist inhibition was observed in antibiotic assays (r = 0.6, P

Zhou 8425B, possessing the leaf rust resistance gene LrZH84, is an elite wheat (Triticum aestivum) parental line in the Yellow-Huai Valley region of China. In the present study, 2,086 F2 plants derived from Zhou 8425B/Chinese Spring were used for fine mapping of LrZH84 with expressed sequence tag (EST) and sequence-tagged site (STS) markers. Seventy inter-simple sequence repeat EST and STS markers on 1BL were used to screen the two parents and resistant and susceptible bulks; those polymorphic were used to analyze the entire F2 population. Three EST markers (BF474863, BE497107, and CD373538) were closely linked to LrZH84, with genetic distances of 0.7, 0.7, and 1.7 cM, respectively. STS marker Hbsf-1 was developed from the sequences of polymerase chain reaction fragments amplified from EST marker BF474863. LrZH84 was 8.19 cM proximal to Lr44, but may be allelic to LrXi and LrG98 although they showed different reactions with some Puccinia triticina pathotypes.

Leaf rust, caused by Puccinia triticina, is one of the most widespread diseases in common wheat (Triticum aestivum L.) worldwide. With the objective of identifying and mapping new genes for resistance to leaf rust, F(1), F(2) plants and F(3) lines from a cross between resistant line Zhou 8425B and susceptible line Chinese Spring were inoculated with Chinese P. triticina races THTT and MBHP in the greenhouse. A total of 793 pairs of SSR primers were used to test the parents and resistant and susceptible bulks. Seven polymorphic chromosome 1B markers were used for genotyping the F(2) and F(3) populations. Zhou 8425B carried a single dominant resistance gene, temporarily designated LrZH84, linked to SSR markers gwm582 and barc8 with genetic distances of 3.9 and 5.2 cM, respectively. The Xbarc8 allele co-segregated with Lr26 in the F(3) population. The Xgwm582 allele associated with LrZH84 was identified as a leaf rust resistance gene and shown to be present in the Predgornaia 2 parent of Zhou 8425B. The seedling reaction pattern of LrZH84 was different from those of lines with Lr26, Lr33, Lr44 and Lr46, all of which are located in chromosome 1B. It was concluded that LrZH84 is likely to be a new leaf rust resistance gene.

In spring 2004, potato scab disease was observed on potato tubers (Solanum tuberosum cv. Favorita) at approximately 5–10% incidence in fields in Shandong province, China. Scabby tubers had brown, superficial or pitted corky lesions that were somewhat different from typical symptoms (for example, superficial, raised or pitted lesions) of potato scab caused by Streptomyces scabies. Both traditional and PCR-based methods were employed to identify the causal agent. A Streptomyces sp. strain CPS-3 was isolated from the lesion of a scabby potato tuber on oatmeal agar. It produced rectiflexuous spore chains, and the spores were white with smooth surface and 0AE4–0AE5 · 0AE9–1AE1 lm in size. The strain did not produce melanin on tyrosine-peptone-yeast extract agar medium, but produced diffusible yellow pigments, utilized all the International Streptomyces Project (ISP) sugars as single carbon sources (Shirling & Gottlieb, 1966), and L-hydroxyproline, L-histidine as sole nitrogen sources but not L-methionine. It grew at pH 4AE0 and was susceptible to phenol (0AE1%) and crystal violet (0AE5 lg ⁄ mL), but not to penicillin (10 IU ⁄ mL) and streptomycin (20 lg ⁄ mL). It did not produce H2S. The 16S rRNA sequence of the strain was amplified using the primers S1 (5¢CATTCACGGAGAGTTTGATCC-3¢) and S2 (5¢-AGAAAGGAGGT GATCCAGCC-3¢). The resulting 1460 bp sequence (GenBank Accession No. AY621376) had the highest similarity (99AE8%) with S. acidiscabies type strainATCC 49003 (AB026220). The strain is identical to S. acidiscabiesbasedon theabovecharacteristics (LambertL Loria et al., 1997) but this is the first report of S. acidiscabies causing potato scab in China.