A large deletion conferring pale green leaves of maize.

BACKGROUND: The structural basis of chloroplast and the regulation of chloroplast biogenesis remain largely unknown in maize. Gene mutations in these pathways have been linked to the abnormal leaf color phenotype observed in some mutants. Large scale structure variants (SVs) are crucial for genome evolution, but few validated SVs have been reported in maize and little is known about their functions though they are abundant in maize genomes. RESULTS: In this research, a spontaneous maize mutant, pale green leaf-shandong (pgl-sd), was studied. Genetic analysis showed that the phenotype of pale green leaf was controlled by a recessive Mendel factor mapped to a 156.8-kb interval on the chromosome 1 delineated by molecular markers gy546 and gy548. There were 7 annotated genes in this interval. Reverse transcription quantitative PCR analysis, SV prediction, and de novo assembly of pgl-sd genome revealed that a 137.8-kb deletion, which was verified by Sanger sequencing, might cause the pgl-sd phenotype. This deletion contained 5 annotated genes, three of which, including Zm00001eb031870, Zm00001eb031890 and Zm00001eb031900, were possibly related to the chloroplast development. Zm00001eb031870, encoding a Degradation of Periplasmic Proteins (Deg) homolog, and Zm00001eb031900, putatively encoding a plastid pyruvate dehydrogenase complex E1 component subunit beta (ptPDC-E1-ß), might be the major causative genes for the pgl-sd mutant phenotype. Plastid Degs play roles in protecting the vital photosynthetic machinery and ptPDCs provide acetyl-CoA and NADH for fatty acid biosynthesis in plastids, which were different from functions of other isolated maize leaf color associated genes. The other two genes in the deletion were possibly associated with DNA repair and disease resistance, respectively. The pgl-sd mutation decreased contents of chlorophyll a, chlorophyll b, carotenoids by 37.2%, 22.1%, and 59.8%, respectively, and led to abnormal chloroplast. RNA-seq revealed that the transcription of several other genes involved in the structure and function of chloroplast was affected in the mutant. CONCLUSIONS: It was identified that a 137.8-kb deletion causes the pgl-sd phenotype. Three genes in this deletion were possibly related to the chloroplast development, which may play roles different from that of other isolated maize leaf color associated genes.

Endoscopic Submucosal Dissection Versus Radical Surgery for T1 Superficial Esophageal Cell Carcinoma: a Subgroup Survival Analysis.

BACKGROUND: With the continuous advent of magnifying endoscopy, endoscopic submucosal dissection (ESD) has gradually become the mainstream treatment for early esophageal cancer. We aimed to compare the outcomes of patients with T1 superficial esophageal cell carcinoma treated with ESD vs. esophagectomy. METHODS: We retrospectively analyzed patients who underwent ESD or radical surgery at the First Affiliated Hospital of Nanchang University from January 1, 2010, to December 31, 2018. The purpose of propensity score matching is to reduce selection bias. Precise subgroup analysis according to depth of invasion was performed to reduce the influence of confounding factors. RESULT: We reviewed patients who underwent ESD (n = 117) or radical surgery (n = 217) at the First Affiliated Hospital of Nanchang University from 2010 to 2018. The OS rate and progression-free survival rate in the ESD group were better than those in the surgery group (OS, P = 0.002. PFS, P = 0.004). The ESD group had a lower early adverse event rate (74.6% vs. 91%, P = 0.012), shorter hospital stays (median 10 days vs. 18 days, P < 0.001), and lower hospitalization costs (median 15,455 vs. 62,376 RMB, P < 0.001). Multivariate Cox regression analysis found that the treatment method was an independent risk factor affecting the prognosis of patients with superficial esophageal cancer, and the death risk of patients in the ESD group was 0.377 times that of the radical surgery group (HR = 0.377, P = 0.023). We conducted a subgroup analysis of patients again according to the depth of invasion; 37 pairs of patients were included in the T1a stage, and 19 pairs of patients were included in the T1b stage. In T1a and T1b patients, the difference in OS rate and PFS rate between the two treatments was statistically significant (T1a, OS, P = 0.002, PFS, P = 0.004; T1b, OS, P = 0.019, PFS, P = 0.022), and the OS rates in the ESD group were better than those in the radical surgery group. CONCLUSION: For patients with T1b superficial esophageal cancer, ESD has a longer overall survival and progression-free survival compared with radical surgery. These results support ESD as the preferred treatment for stage T1b superficial esophageal cancer.

Epifriedelinol Ameliorates the Neuropathic Pain and Recovers the Function in Spinal Cord Injury by Downregulation of Neuronal Apoptosis and NMDA Receptor.

Spinal cord injury (SCI) is commonly associated with neuropathic pain, which affects large population. Thus, the presented investigation evaluates the beneficial effect of epifriedelinol against SCI-associated neuropathic pain. SCI injury was induced in rats by clip-compression and rats were treated with epifriedelinol 100 and 200 mg/kg, i.p. for 21 days after the induction of SCI. The effect of epifriedelinol was assessed on neuropathic pain by mechanical allodynia and locomotor function. Level of inflammatory cytokines were assessed in the neuronal tissue using enzyme linked immunosorbent assay (ELISA) and expression of caspase-3 and Bcl2 protein were assessed by western blot assay. Data of investigation reveals that epifriedelinol reduces mechanical allodynia in SCI injured rats. Moreover, it also improves locomotor function in SCI injured rats. There was significant decrease in level of interleukin (IL)-1ß, IL-6 and tumor necrosis factor (TNF)-α in the neuronal tissues of epifriedelinol-treated group than negative control group. Moreover, treatment with epifriedelinol ameliorates the altered expression of caspase 3, Bcl2 and GluN1 and level of glutamate in neuronal tissue of SCI-injured rats. In conclusion, data reveal that epifriedelinol treatment protects neuropathic pain associated with spinal cord injury by downregulating the N-methyl-D-aspartate (NMDA) receptor function.

Suppressing chlorophyll degradation by silencing OsNYC3 improves rice resistance to Rhizoctonia solani, the causal agent of sheath blight.

Necrotrophic fungus Rhizoctonia solani Kühn (R. solani) causes serious diseases in many crops worldwide, including rice and maize sheath blight (ShB). Crop resistance to the fungus is a quantitative trait and resistance mechanism remains largely unknown, severely hindering the progress on developing resistant varieties. In this study, we found that resistant variety YSBR1 has apparently stronger ability to suppress the expansion of R. solani than susceptible Lemont in both field and growth chamber conditions. Comparison of transcriptomic profiles shows that the photosynthetic system including chlorophyll biosynthesis is highly suppressed by R. solani in Lemont but weakly in YSBR1. YSBR1 shows higher chlorophyll content than that of Lemont, and inducing chlorophyll degradation by dark treatment significantly reduces its resistance. Furthermore, three rice mutants and one maize mutant that carry impaired chlorophyll biosynthesis all display enhanced susceptibility to R. solani. Overexpression of OsNYC3, a chlorophyll degradation gene apparently induced expression by R. solani infection, significantly enhanced ShB susceptibility in a high-yield ShB-susceptible variety '9522'. However, silencing its transcription apparently improves ShB resistance without compromising agronomic traits or yield in field tests. Interestingly, altering chlorophyll content does not affect rice resistance to blight and blast diseases, caused by biotrophic and hemi-biotrophic pathogens, respectively. Our study reveals that chlorophyll plays an important role in ShB resistance and suppressing chlorophyll degradation induced by R. solani infection apparently improves rice ShB resistance. This discovery provides a novel target for developing resistant crop to necrotrophic fungus R. solani.

Heterologous expression of ZmGS5 enhances organ size and seed weight by regulating cell expansion in Arabidopsis thaliana.

Maize ZmGS5 was reported to be positively associated with kernel-related traits, however, its regulatory mechanism on plant development and seed size remains unknown. In this study, ZmGS5 was demonstrated to be widely expressed in various maize tissues with the highest expression level in developing embryos, indicating its critical roles in early kernel development process. The ZmGS5 protein was subcellularly localized to both the nucleus and cytoplasm. Transgenic Arabidopsis plants overexpressing ZmGS5 under the control of either the constitutive maize Ubiquitin1 promotor or native ZmGS5 promoter resulted in increased plant size, biomass, seed size and weight, although no significant difference was observed between transgenic lines harboring the two constructs. In contrast, the antisense-ZmGS5 transgene resulted in opposite phenotypes. Our cytological data suggested that ZmGS5 enlarged petal size through enhancing cell expansion. Quantitative RT-PCR analysis indicated that ZmGS5 might enhance cell expansion and grain filling by upregulating expression levels of particular EXPA or SWEET genes. Collectively, these findings help us further understand the biological function and regulatory mechanism of ZmGS5 in improving organ size and seed weight, which imply its great potential for high-yield breeding in the future.

Overexpression of an Antisense RNA of Maize Receptor-Like Kinase Gene ZmRLK7 Enlarges the Organ and Seed Size of Transgenic Arabidopsis Plants.

Leucine-rich repeat (LRR)-receptor-like protein kinases (LRR-RLKs) play vital roles in plant growth, development, and responses to environmental stresses. In this study, a new LRR-RLK gene, ZmRLK7, was isolated from maize, and its function within plant development was investigated through ectopic expression in Arabidopsis. The spatial expression pattern analysis reveals that ZmRLK7 is highly expressed in embryos prior to programmed cell death (PCD) of starchy endosperm tissues, and its encoded protein has been localized to both plasm and nuclear membranes subcellularly. Overexpression of sense ZmRLK7 reduced the plant height, organ size (e.g., petals, silique, and seeds), and 1000-seed weight in transgenic lines, while the antisense transgene enlarged these traits. Cytological analysis suggested that ZmRLK7 negatively regulates petal size through restricting both cell expansion and proliferation. In addition, abnormal epidermal cell structure was observed, and the stomata number decreased obviously in sense ZmRLK7 transgenic lines with a lower stomatal index than that in the wild type. Quantitative RT-PCR analysis indicated that transcript levels of genes that are involved in the brassinosteroid and ERACTA signaling pathways were coordinately altered, which could partially explain the phenotypic variation. Moreover, overexpression of antisense ZmRLK7 substantially rescued the Arabidopsis bak1-3 mutant phenotype. All these results together suggest that ZmRLK7 can serve as an important regulator in regulating plant architecture and organ size formation. This work will provide insight into the function of ZmRLK7 in maize.

Genome-wide characterization of the abscisic acid-, stress- and ripening-induced (ASR) gene family in wheat (Triticum aestivum L.).

BACKGROUND: Abscisic acid-, stress-, and ripening-induced (ASR) genes are a class of plant specific transcription factors (TFs), which play important roles in plant development, growth and abiotic stress responses. The wheat ASRs have not been described in genome-wide yet. METHODS: We predicted the transmembrane regions and subcellular localization using the TMHMM server, and Plant-mPLoc server and CELLO v2.5, respectively. Then the phylogeny tree was built by MEGA7. The exon-intron structures, conserved motifs and TFs binding sites were analyzed by GSDS, MEME program and PlantRegMap, respectively. RESULTS: In wheat, 33ASR genes were identified through a genome-wide survey and classified into six groups. Phylogenetic analyses revealed that the TaASR proteins in the same group tightly clustered together, compared with those from other species. Duplication analysis indicated that the TaASR gene family has expanded mainly through tandem and segmental duplication events. Similar gene structures and conserved protein motifs of TaASRs in wheat were identified in the same groups. ASR genes contained various TF binding cites associated with the stress responses in the promoter region. Gene expression was generally associated with the expected group-specific expression pattern in five tissues, including grain, leaf, root, spike and stem, indicating the broad conservation of ASR genes function during wheat evolution. The qRT-PCR analysis revealed that several ASRs were up-regulated in response to NaCl and PEG stress. CONCLUSION: We identified ASR genes in wheat and found that gene duplication events are the main driving force for ASR gene evolution in wheat. The expression of wheat ASR genes was modulated in responses to multiple abiotic stresses, including drought/osmotic and salt stress. The results provided important information for further identifications of the functions of wheat ASR genes and candidate genes for high abiotic stress tolerant wheat breeding.

Genome-wide characterization of the abscisic acid-, stress- and ripening-induced (ASR) gene family in wheat (Triticum aestivum L)

BACKGROUND: Abscisic acid-, stress-, and ripening-induced (ASR) genes are a class of plant specific transcription factors (TFs), which play important roles in plant development, growth and abiotic stress responses. The wheat ASRs have not been described in genome-wide yet. METHODS: We predicted the transmembrane regions and subcellular localization using the TMHMM server, and Plant-mPLoc server and CELLO v2.5, respectively. Then the phylogeny tree was built by MEGA7. The exon-intron structures, conserved motifs and TFs binding sites were analyzed by GSDS, MEME program and PlantRegMap, respectively. RESULTS: In wheat, 33ASR genes were identified through a genome-wide survey and classified into six groups. Phylogenetic analyses revealed that the TaASR proteins in the same group tightly clustered together, compared with those from other species. Duplication analysis indicated that the TaASR gene family has expanded mainly through tandem and segmental duplication events. Similar gene structures and conserved protein motifs of TaASRs in wheat were identified in the same groups. ASR genes contained various TF binding cites associated with the stress responses in the promoter region. Gene expression was generally associated with the expected group-specific expression pattern in five tissues, including grain, leaf, root, spike and stem, indicating the broad conservation of ASR genes function during wheat evolution. The qRT-PCR analysis revealed that several ASRs were up-regulated in response to NaCl and PEG stress. CONCLUSION: We identified ASR genes in wheat and found that gene duplication events are the main driving force for ASR gene evolution in wheat. The expression of wheat ASR genes was modulated in responses to multiple abiotic stresses, including drought/osmotic and salt stress. The results provided important information for further identifications of the functions of wheat ASR genes and candidate genes for high abiotic stress tolerant wheat breeding.

Overexpression of maize sucrose non-fermenting-1-related protein kinase 1 genes, ZmSnRK1s, causes alteration in carbon metabolism and leaf senescence in Arabidopsis thaliana.

Sucrose non-fermenting-1 (SNF1) -related protein kinase 1 (SnRK1) is a key regulator of catabolic homeostasis and plays critical roles in plant development and stress response. In this study, three SNF1-related protein kinase 1 genes, ZmSnRK1.1, ZmSnRK1.2 and ZmSnRK1.3, which are highly conserved in plants, were isolated from maize (Zea mays L.). Expression profiling experiments indicated that the three genes were constitutively expressed in all tested tissues with the highest expression level in young ears. Subcellular localization analysis indicated that ZmSnRK1.1, ZmSnRK1.2 and ZmSnRK1.3 are localized to both the nucleus and cytoplasm. Transgenic Arabidopsis lines overexpressing ZmSnRK1.1, ZmSnRK1.2 or ZmSnRK1.3 exhibited hypersensitivity to exogenous sugar treatment and accumulated less glucose but more sucrose in the rosette leaves and mature seeds compared to the wild type. Time to flowering was shortened in the ZmSnRK1.1 over-expressing lines but prolonged in the ZmSnRK1.2 and ZmSnRK1.3 lines. Leaf senescence was delayed in all transgenic lines, especially in the ZmSnRK1.3 lines, which led to enhanced biomass and seed yield at maturity. Key genes that are involved in carbon metabolism, senescence and flowering time were differentially regulated in the transgenic lines as revealed by the RNA-seq analysis. This study demonstrated that maize ZmSnRK1 members play important roles in energy sensing and carbon metabolism, they regulate the architecture shaping and developmental transition when heterogeneously expressed in Arabidopsis and may provide potentially valuable characteristics for high yield breeding of crops in the future.

Complexes of Felodipine Nanoparticles With Zein Prepared Using a Dual Shift Technique.

To improve the dissolution of felodipine, felodipine-zein complexes were prepared using a dual shift technique, with zein as both stabilizer and carrier. The complexes were characterized by particle size, zeta potential, morphology, crystalline properties, and release behavior. The complexes could be prepared in high yield and showed good redispersibility. The mean diameters of the felodipine particles in complexes were 150-300 nm, with negative zeta potentials of -30 to -25 mV after rehydration, and the particle sizes of the complexes were in the range 10-80 µm. The size of the felodipine nanoparticles incorporated into zein increased gradually with increasing drug content. Powder X-ray diffraction and differential scanning calorimetry indicated that felodipine in the complexes was markedly less crystalline than the pure drug. Both the rate and extent of dissolution of the complexes were significantly greater than those of the active pharmaceutical ingredient or physical mixtures. Spectroscopic analyses indicated that intermolecular interactions, especially hydrophobic interactions, are the major driving forces for the formation of the felodipine nanoparticles and contribute to the stabilization effect. This study provides a promising strategy for enhancing the dissolution rate of drugs using simplified preparation processes and showcases the design of zein-based oral delivery systems for bioactive components.

Dissection of Recombination Attributes for Multiple Maize Populations Using a Common SNP Assay.

Recombination is a vital characteristic for quantitative trait loci mapping and breeding to enhance the yield potential of maize. However, recombination characteristics in globally used segregating populations have never been evaluated at similar genetic marker densities. This study aimed to divulge the characteristics of recombination events, recombinant chromosomal segments, and recombination frequency for four dissimilar populations. These populations were doubled haploid (DH), recombination inbred line (RIL), intermated B73xMo17 (IBM), and multi-parent advanced generation inter-cross (MAGIC), using the Illumina MaizeSNP50 BeadChip to provide markers. Our results revealed that the average number of recombination events was 16, 41, 72, and 86 per line in DH, RIL, IBM, and MAGIC populations, respectively. Accordingly, the average length of recombinant chromosomal segments was 84.8, 47.3, 29.2, and 20.4 Mb in DH, RIL, IBM, and MAGIC populations, respectively. Furtherly, the recombination frequency varied in different genomic regions and population types [DH (0-12.7 cM/Mb), RIL (0-15.5 cM/Mb), IBM (0-24.1 cM/Mb), MAGIC (0-42.3 cM/Mb)]. Utilizing different sub-sets of lines, the recombination bin number and size were analyzed in each population. Additionally, different sub-sets of markers and lines were employed to estimate the recombination bin number and size via formulas for relationship in these populations. The relationship between recombination events and recombination bin length was also examined. Our results contribute to determining the most suitable number of genetic markers, lines in each population, and population type for successful mapping and breeding.

Fine Mapping and Candidate Gene Analysis of the Leaf-Color Gene ygl-1 in Maize.

A novel yellow-green leaf mutant yellow-green leaf-1 (ygl-1) was isolated in self-pollinated progenies from the cross of maize inbred lines Ye478 and Yuanwu02. The mutant spontaneously showed yellow-green character throughout the lifespan. Meanwhile, the mutant reduced contents of chlorophyll and Car, arrested chloroplast development and lowered the capacity of photosynthesis compared with the wild-type Lx7226. Genetic analysis revealed that the mutant phenotype was controlled by a recessive nuclear gene. The ygl-1 locus was initially mapped to an interval of about 0.86 Mb in bin 1.01 on the short arm of chromosome 1 using 231 yellow-green leaf individuals of an F2 segregating population from ygl-1/Lx7226. Utilizing four new polymorphic SSR markers, the ygl-1 locus was narrowed down to a region of about 48 kb using 2930 and 2247 individuals of F2 and F3 mapping populations, respectively. Among the three predicted genes annotated within this 48 kb region, GRMZM2G007441, which was predicted to encode a cpSRP43 protein, had a 1-bp nucleotide deletion in the coding region of ygl-1 resulting in a frame shift mutation. Semi-quantitative RT-PCR analysis revealed that YGL-1 was constitutively expressed in all tested tissues and its expression level was not significantly affected in the ygl-1 mutant from early to mature stages, while light intensity regulated its expression both in the ygl-1 mutant and wild type seedlings. Furthermore, the mRNA levels of some genes involved in chloroplast development were affected in the six-week old ygl-1 plants. These findings suggested that YGL-1 plays an important role in chloroplast development of maize.

Characterization, fine mapping and expression profiling of Ragged leaves1 in maize.

The Ragged leaves1 (Rg1) maize mutant frequently develops lesions on leaves, leaf sheaths, and ear bracts. Lesion formation is independent of biotic stress. High-level accumulation of H(2)O(2) revealed by staining Rg1 leaves, with 3',3'-diaminobenzidine and trypan blue, suggested that lesion formation appeared to be due to cell death. Rg1 was initially mapped to an interval around 70.5 Mb in bin 3.04 on the short arm of chromosome 3. Utilizing 15 newly developed markers, Rg1 was delimitated to an interval around 17 kb using 16,356 individuals of a BC1 segregating population. There was only one gene, rp3, predicted in this region according to the B73 genome. Analysis of transcriptome data revealed that 441 genes significantly up-regulated in Rg1 leaves were functionally over-represented. Among those genes, several were involved in the production of reactive oxygen species (ROS). Our results suggested that lesions of Rg1 maize arose probably due to an aberrant rust resistance allele of Rp3, which elicited the accumulation of ROS independent of biotic stress.

Identification and fine mapping of rhm1 locus for resistance to Southern corn leaf blight in maize.

rhm1 is a major recessive disease resistance locus for Southern corn leaf blight (SCLB). To further narrow down its genetic position, F(2) population and BC(1) F(1) population derived from the cross between resistant (H95(rhm) ) and susceptible parents (H95) of maize (Zea mays) were constructed. Using newly developed markers, rhm1 was initially delimited within an interval of 2.5 Mb, and then finally mapped to a 8.56 kb interval between InDel marker IDP961-503 and simple sequence repeat (SSR) marker A194149-1. Three polymorphic markers IDP961-504, IDP B2-3 and A194149-2 were shown to be co-segregated with the rhm1 locus. Sequence analysis of the 8.56 kb DNA fragment revealed that it contained only one putative gene with a predicted amino acid sequence identical to lysine histidine transporter 1 (LHT1). Comparative sequence analysis indicated that the LHT1 in H95(rhm) harbors a 354 bp insertion in its third exon as compared with that of susceptible alleles in B73, H95 and Mo17. The 354 bp insertion resulted in a truncation of the predicted protein of candidate resistance allele (LHT1-H95(rhm) ). Our results strongly suggest LHT1 as the candidate gene for rhm1 against SCLB. The tightly linked molecular markers developed in this study can be directly used for molecular breeding of resistance to Southern corn leaf blight in maize.

Extensive, clustered parental imprinting of protein-coding and noncoding RNAs in developing maize endosperm.

Although genetic imprinting was discovered in maize 40 years ago, its exact extent in the triploid endosperm remains unknown. Here, we have analyzed global patterns of allelic gene expression in developing maize endosperms from reciprocal crosses between inbreds B73 and Mo17. We have defined an imprinted gene as one in which the relative expression of the maternal and paternal alleles differ at least fivefold in both hybrids of the reciprocal crosses. We found that at least 179 genes (1.6% of protein-coding genes) expressed in the endosperm are imprinted, with 68 of them showing maternal preferential expression and 111 paternal preferential expression. Additionally, 38 long noncoding RNAs were imprinted. The latter are transcribed in either sense or antisense orientation from intronic regions of normal protein-coding genes or from intergenic regions. Imprinted genes show a clear pattern of clustering around the genome, with a number of imprinted genes being adjacent to each other. Analysis of allele-specific methylation patterns of imprinted loci in the hybrid endosperm identified 21 differentially methylated regions (DMRs) of several hundred base pairs in length, corresponding to both imprinted genes and noncoding transcripts. All DMRs identified are uniformly hypomethylated in maternal alleles and hypermethylated in paternal alleles, regardless of the imprinting direction of their corresponding loci. Our study indicates highly extensive and complex regulation of genetic imprinting in maize endosperm, a mechanism that can potentially function in the balancing of the gene dosage of this triploid tissue.

Genetic and comparative genomics mapping reveals that a powdery mildew resistance gene Ml3D232 originating from wild emmer co-segregates with an NBS-LRR analog in common wheat (Triticum aestivum L.).

Powdery mildew caused by Blumeria graminis f. sp. tritici is one of the most important wheat diseases worldwide and breeding for resistance using diversified disease resistance genes is the most promising approach to prevent outbreaks of powdery mildew. A powdery mildew resistance gene, originating from wild emmer wheat (Triticum turgidum var. dicoccoides) accessions collected from Israel, has been transferred into the hexaploid wheat line 3D232 through crossing and backcrossing. Inoculation results with 21 B. graminis f. sp. tritici races indicated that 3D232 is resistant to all of the powdery mildew isolates tested. Genetic analyses of 3D232 using an F(2) segregating population and F(3) families indicated that a single dominant gene, Ml3D232, confers resistance in the host seedling stage. By applying molecular markers and bulked segregant analysis (BSA), we have identified polymorphic simple sequence repeats (SSR), expressed sequence tags (EST) and derived sequence tagged site (STS) markers to determine that the Ml3D232 is located on chromosome 5BL bin 0.59-0.76. Comparative genetic analyses using mapped EST markers and genome sequences of rice and Brachypodium established co-linearity of the Ml3D232 genomic region with a 1.4 Mb genomic region on Brachypodium distachyon chromosome 4, and a 1.2 Mb contig located on the Oryza sativa chromosome 9. Our comparative approach enabled us to develop new EST-STS markers and to delimit the genomic region carrying Ml3D232 to a 0.8 cM segment that is collinear with a 558 kb region on B. distachyon. Eight EST markers, including an NBS-LRR analog, co-segregated with Ml3D232 to provide a target site for fine genetic mapping, chromosome landing and map-based cloning of the powdery mildew resistance gene. This newly developed common wheat germplasm provides broad-spectrum resistance to powdery mildew and a valuable resource for wheat breeding programs.