Characterization of low-molecular-weight glutenin genes in <Emphasis Type="Italic">Aegilops tauschii</Emphasis>

This paper reports the characterization of the low-molecular-weight (LMW) glutenin gene family of Aegilops tauschii (syn. Triticum tauschii), the D-genome donor of hexaploid wheat. By analysis of bacterial artificial chromosome (BAC) clones positive for hybridization with an LMW glutenin probe, seven unique LMW glutenin genes were identified. These genes were sequenced, including their untranslated 3 and 5 flanking regions. The deduced amino acid sequences of the genes revealed four putative active genes and three pseudogenes. All these genes had a very high level of similarity to LMW glutenins characterized in hexaploid wheat. The predicted molecular weights of the mature proteins were between 32.2 kDa and 39.6 kDa, and the predicted isoelectric points of the proteins were between 7.53 and 8.06. All the deduced proteins were of the LMW-m type. The organization of the seven LMW glutenin genes appears to be interspersed over at least several hundred kilo base pairs, as indicated by the presence of only one gene or pseudogene per BAC clone. Southern blot analysis of genomic DNA of Ae. tauschii and the BAC clones containing the seven LMW glutenin genes indicated that the BAC clones contained all LMW glutenin-hybridizing bands present in the genome. Two-dimensional gel electrophoresis of an LMW glutenin extract from Ae. tauschii was conducted and showed the presence of at least 11 distinct proteins. Further analysis indicated that some of the observed proteins were modified gliadins. These results suggest that the actual number of typical LMW glutenins may in fact be much lower than previously thought, with a number of modified gliadins also being present in the polymeric fraction.     

Overexpression of the Bx7 high molecular weight glutenin subunit on the <Emphasis Type="Italic">Glu</Emphasis>-<Emphasis Type="Italic">B1</Emphasis> locus in a Korean wheat landrace

The Glu-B1al (Bx7^OE + By8) allele is important for bread-making quality. The allele was found in a Korean wheat landrace using specific DNA markers. Molecular analyses were conducted to identify the overexpressed Bx7 (Bx7^OE) subunit of the allele. The Korean wheat landrace (accession ID: IT166460) showed a similar protein expression level of Bx7 subunit, i.e., overexpression of Bx7 subunit towards cv. Glenlea, Canadian Western Red Spring wheat, which harbors Bx7^OE subunit of Glu-B1al as detected on SDS–PAGE (sodium dodecyl sulfate poly-acrylamide gel electrophoresis). In addition, 2-DE (two-dimensional electrophoresis) analysis revealed similar protein expression patterns of the Bx7 subunit regions of IT166460 and Glenlea. The proportion of Bx7 to total HMW-GSs (high molecular weight glutenin subunits) in IT166460 (56.17 ± 0.22%) was higher than that of Chinese Spring (34.75 ± 1.03%) and even that of Glenlea (46.25 ± 1.76%) as assessed by RP-HPLC (reverse-phase high-performance liquid chromatography). Overexpression of Bx7 subunit was caused by gene duplication and indels of the promoter region of the Bx7 gene. IT166460 attained the 43 bp indel of the promoter region, as did Glenlea, i.e., the amplicon size of IT166460 was the same as that of Glenlea. In addition, the nucleotides present in the duplicated gene in IT166460 were the same as those in Glenlea. Bx7^OE subunit is critical for dough strength. However, most wheat accessions harboring the subunit are distributed in America. Furthermore, most Korean wheats have little genetic variation in glutenin composition and are associated with inferior bread quality. Hence, IT166460 could be used to improve bread-making quality in the Korean wheat breeding program.     

Identification of <Emphasis Type="Italic">Pm58</Emphasis> from <Emphasis Type="Italic">Aegilops tauschii</Emphasis>

Key message

A novel powdery mildew-resistance gene, designated Pm58, was introgressed directly from Aegilops tauschii to hexaploid wheat, mapped to chromosome 2DS, and confirmed to be effective under field conditions. Selectable KASP? markers were developed for MAS.

Abstract

Powdery mildew caused by Blumeria graminis (DC.) f. sp. tritici (Bgt) remains a significant threat to wheat (Triticum aestivum L.) production. The rapid breakdown of race-specific resistance to Bgt reinforces the need to identify novel sources of resistance. The d-genome species, Aegilops tauschii, is an excellent source of disease resistance that is transferrable to T. aestivum. The powdery mildew-resistant Ae. tauschii accession TA1662 (2n?=?2x?=?DD) was crossed directly with the susceptible hard white wheat line KS05HW14 (2n?=?6x?=?AABBDD) followed by backcrossing to develop a population of 96 BC₂F₄ introgression lines (ILs). Genotyping-by-sequencing was used to develop a genome-wide genetic map that was anchored to the Ae. tauschii reference genome. A detached-leaf Bgt assay was used to screen BC₂F_4:6 ILs, and resistance was found to segregate as a single locus (χ?=?2.0, P value?=?0.157). The resistance gene, referred to as Pm58, mapped to chromosome 2DS. Pm58 was evaluated under field conditions in replicated trials in 2015 and 2016. In both years, a single QTL spanning the Pm58 locus was identified that reduced powdery mildew severity and explained 21% of field variation (P value?<?0.01). KASP? assays were developed from closely linked GBS-SNP markers, a refined genetic map was developed, and four markers that cosegregate with Pm58 were identified. This novel source of powdery mildew-resistance and closely linked genetic markers will support efforts to develop wheat varieties with powdery mildew resistance.

     

Genetic diversity of <Emphasis Type="Italic">avenin-like b</Emphasis> genes in <Emphasis Type="Italic">Aegilops tauschii</Emphasis> Coss

Avenin-like storage proteins influence the rheological properties and processing quality in common wheat, and the discovery of new alleles will benefit wheat quality improvement. In this study, 13 avenin-like b alleles (TaALPb7D-A–M) were discovered in 108 Aegilops tauschii Coss. accessions. Ten alleles were reported for the first time, while the remaining three alleles were the same as alleles in other species. A total of 15 nucleotide changes were detected in the 13 alleles, resulting in only 11 amino acid changes because of synonymous mutations. Alleles TaALPb7D-E, TaALPb7D-G, and TaALPb7D-J encoded the same protein. These polymorphic sites existed in the N-terminus, Repetitive region (Left), Repetitive region (Right) and C-terminus domains, with no polymorphisms in the signal peptide sequence nor in those encoding the 18 conserved cysteine residues. Phylogenetic analysis divided the TaALPb7Ds into four clades. The Ae. tauschii alleles were distributed in all four clades, while the alleles derived from common wheat, TaALPb7D-G and TaALPb7D-C, belonged to clade III and IV, respectively. Alleles TaALPb7D-G and TaALPb7D-C were the most widely distributed, being present in nine and six countries, respectively. Iran and Turkey exhibited the highest genetic diversity with respect to TaALPb7D alleles, accessions from these countries carrying seven and six alleles, respectively, which implied that these countries were the centers of origin of the avenin-like b gene. The new alleles discovered and the phylogenetic analysis of avenin-like b genes will provide breeding materials and a theoretical basis for wheat quality improvement.     

Fine genetic mapping of greenbug aphid-resistance gene <Emphasis Type="Italic">Gb3</Emphasis> in <Emphasis Type="Italic">Aegilops tauschii</Emphasis>

The greenbug, Schizaphis graminum (Rondani), is an important aphid pest of small grain crops especially wheat (Triticum aestivum L., 2n = 6x = 42, genomes AABBDD) in many parts of the world. The greenbug-resistance gene Gb3 originated from Aegilops tauschii Coss. (2n = 2x = 14, genome D^tD^t) has shown consistent and durable resistance against prevailing greenbug biotypes in wheat fields. We previously mapped Gb3 in a recombination-rich, telomeric bin of wheat chromosome arm 7DL. In this study, high-resolution genetic mapping was carried out using an F_2:3 segregating population derived from two Ae. tauschii accessions, the resistant PI 268210 (original donor of Gb3 in the hexaploid wheat germplasm line ‘Largo’) and susceptible AL8/78. Molecular markers were developed by exploring bin-mapped wheat RFLPs, SSRs, ESTs and the Ae. tauschii physical map (BAC contigs). Wheat EST and Ae. tauschii BAC end sequences located in the deletion bin 7DL3-0.82–1.00 were used to design STS (sequence tagged site) or CAPS (Cleaved Amplified Polymorphic Sequence) markers. Forty-five PCR-based markers were developed and mapped to the chromosomal region spanning the Gb3 locus. The greenbug-resistance gene Gb3 now was delimited in an interval of 1.1 cM by two molecular markers (HI067J6-R and HI009B3-R). This localized high-resolution genetic map with markers closely linked to Gb3 lays a solid foundation for map based cloning of Gb3 and marker-assisted selection of this gene in wheat breeding.     

Chromosomal location of <Emphasis Type="Italic">Pm35</Emphasis>, a novel <Emphasis Type="Italic">Aegilops tauschii</Emphasis> derived powdery mildew resistance gene introgressed into common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

A single gene controlling powdery mildew resistance was identified in the North Carolina germplasm line NC96BGTD3 (NCD3) using genetic analysis of F₂ derived lines from a NCD3 X Saluda cross. Microsatellite markers linked to this Pm gene were identified and their most likely order was Xcfd7, 10.3 cM, Xgdm43, 8.6 cM, Xcfd26, 11.9 cM, Pm gene. These markers and the Pm gene were assigned to chromosome 5DL by means of Chinese Spring Nullitetrasomic (Nulli5D-tetra5A) and ditelosomic (Dt5DL) lines. A detached leaf test showed a distinctive disease reaction to six pathogen isolates among the NCD3 Pm gene, Pm2 (5DS) and Pm34 (5DL). An allelism test showed independence between Pm34 and the NCD3 Pm gene. Together, the tests provided strong evidence for the presence of a novel Pm gene in NCD3, and this gene was designated Pm35.     

<Emphasis Type="Italic">Sr33</Emphasis> and <Emphasis Type="Italic">Sr35</Emphasis> gene homolog identification in genomes of cereals related to <Emphasis Type="Italic">Aegilops tauschii</Emphasis> and <Emphasis Type="Italic">Triticum monococcum</Emphasis>

Using bioinformatics analysis, the homologs of genes Sr33 and Sr35 were identified in the genomes of Triticum aestivum, Hordeum vulgare, and Triticum urartu. It is known that these genes confer resistance to highly virulent wheat stem rust races (Ug99). To identify amino acid sites important for this resistance, the found homologs were compared with the Sr33 and Sr35 protein sequences. It was found that sequences S5DMA6 and E9P785 are the closest homologs of protein RGAle, a Sr33 gene product, and sequences M7YFA9 (CNL-C) and F2E9R2 are homologs of protein CNL9, a Sr35 gene product. It is assumed that the homologs of genes Sr33 and Sr35, which were obtained from the wild relatives of wheat and barley, can confer resistance to various forms of stem rust and can be used in the future breeding programs aimed at improvement of national wheat varieties.     

Introgression of <Emphasis Type="Italic">Aegilops mutica</Emphasis> genes into common wheat genome

Introgression of genetic material from wheat wild relatives into the common wheat genome remains important. This is a natural and inexhaustible source of enrichment of the wheat gene pool with genes that improve wheat’s adaptive potential. Hexaploid lines F₄–F₅ of wheat type were developed via hybridization of common wheat Aurora (AABBDD) and genome-substituted amphidiploid Aurotica (AABBTT). The hexaploid genome of the latter includes the diploid genome TT from wheat relative Aegilops mutica instead of subgenome DD of common wheat. F₁–F₃ hybrids had limited self-fertility, which had substantially increased for some derivatives in F₄–F₅. For all generations, development of the lines was accompanied by cytogenetic control of the chromosome numbers. The chromosome numbers varied in general from 33 to 46 depending upon generation. In most descendants, that number was 42 chromosomes in F₄ when plants with chromosome numbers 40–44 were selected in each generation. F₅ lines originate from nine selffertile F₂ plants, differ from Aurora according to some morphological characters, and have alien DNA in their genome as was demonstrated by DNA dot-blot hybridization with genomic DNA of Aegilops mutica as a probe.     

Molecular evolution of the clustered <Emphasis Type="Italic">MIC</Emphasis>-<Emphasis Type="Italic">3</Emphasis> multigene family of <Emphasis Type="Italic">Gossypium</Emphasis> species

The Gossypium MIC-3 (Meloidogyne Induced Cotton-3) gene family is of great interest for molecular evolutionary studies because of its uniqueness to Gossypium species, multi-gene content, clustered localization, and root-knot nematode resistance-associated features. Molecular evolution of the MIC-3 gene family was studied in 15 tetraploid and diploid Gossypium genotypes that collectively represent seven phylogenetically distinct genomes. Synonymous (d_S) and non-synonymous (d_N) nucleotide substitution rates suggest that the second of the two exons of the MIC-3 genes has been under strong positive selection pressure, while the first exon has been under strong purifying selection to preserve function. Based on nucleotide substitution rates, we conclude that MIC-3 genes are evolving by a birth-and-death process and that a ‘gene amplification’ mechanism has helped to retain all duplicate copies, which best fits with the “bait and switch” model of R-gene evolution. The data indicate MIC-3 gene duplication events occurred at various rates, once per 1 million years (MY) in the allotetraploids, once per ~2 MY in the A/F genome clade, and once per ~8 MY in the D-genome clade. Variations in the MIC-3 gene family seem to reflect evolutionary selection for increased functional stability, while also expanding the capacity to develop novel “switch” pockets for responding to diverse pests and pathogens. Such evolutionary roles are congruent with the hypothesis that members of this unique resistance gene family provide fitness advantages in Gossypium.     

Identification and genetic characterization of an <Emphasis Type="Italic">Aegilops tauschii</Emphasis> ortholog of the wheat leaf rust disease resistance gene <Emphasis Type="Italic">Lr1</Emphasis>

Aegilops tauschii (goat grass) is the progenitor of the D genome in hexaploid bread wheat. We have screened more than 200 Ae. tauschii accessions for resistance against leaf rust (Puccinia triticina) isolates, which are avirulent on the leaf rust resistance gene Lr1. Approximately 3.5% of the Ae. tauschii accessions displayed the same low infection type as the tester line Thatcher Lr1. The accession Tr.t. 213, which showed resistance after artificial infection with Lr1 isolates both in Mexico and in Switzerland, was chosen for further analysis. Genetic analysis showed that the resistance in this accession is controlled by a single dominant gene, which mapped at the same chromosomal position as Lr1 in wheat. It was delimited in a 1.3-cM region between the restriction fragment length polymorphism (RFLP) markers ABC718 and PSR567 on chromosome 5DL of Ae. tauschii. The gene was more tightly linked to PSR567 (0.47 cM) than to ABC718 (0.79 cM). These results indicate that the resistance gene in Ae. tauschii accession Tr.t. 213 is an ortholog of the leaf rust resistance gene Lr1 of bread wheat, suggesting that Lr1 originally evolved in diploid goat grass and was introgressed into the wheat D genome during or after domestication of hexaploid wheat. Compared to hexaploid wheat, higher marker polymorphism and recombination frequencies were observed in the region of the Lr1 ortholog in Ae. tauschii. The identification of Lr1^Ae, the orthologous gene of wheat Lr1, in Ae. tauschii will allow map-based cloning of Lr1 from this genetically simpler, diploid genome.Hong-Qing Ling and Jiwen Qiu have contributed equally to this work     

Characterization of the new human pleomorphic undifferentiated sarcoma <Emphasis Type="Italic">TP53</Emphasis>-<Emphasis Type="Italic">null</Emphasis> cell line <Emphasis Type="Italic">mfh</Emphasis>-<Emphasis Type="Italic">val2</Emphasis>

Pleomorphic undifferentiated sarcoma (PUS), also called malignant fibrous histiocytoma, is a soft tissue sarcoma which occurs predominantly in the extremities. Its origin is a poorly defined mesenchymal cell, which derives to histiocytic and fibroblastic cells. The patient, a 58 year-old man, presented a lesion located in the forearm composed by spindle cells and multinucleated giant cells, which expressed vimentin and adopted a histological pattern formed by irregular-swirling fascicles. Cells were cultured in vitro and a new cell line was established. We characterized this new cell line by histological analyses, cytogenetics (using G-bands and spectral karyotype technique) and cytometric analyses. Cells were grown in culture for more than 100 passages. They had elongated or polygonal morphology. The cells presented a saturation rate of 70,980 cells/cm², a plating efficiency of 21.5% and a mitotic index of 21 mitoses per field. The cell line was tumorigenic in nude mice. The ploidy study using flow cytometry revealed an aneuploid peak with a DNA index of 1.43. A side population was detected, demonstrating the presence of stem and progenitor cells. Cytogenetics showed a hypotriploid range with many clonal unbalanced rearrangements. Loss of p53 gene was evidenced by MLPA. We describe, for the first time, the characterization of a new human PUS TP53-null cell line called mfh-val2. Mfh-val2 presents a wide number of applications as a TP53-null cell line and a great interest in order to characterize genetic alterations influencing the oncogenesis or progression of PUS and to advance in the biological investigation of this tumor.     

Production of intergeneric hybrid between dwarfing polish wheat (<Emphasis Type="Italic">Triticum polonicum</Emphasis> L.) and <Emphasis Type="Italic">Aegilops tauschii</Emphasis> Cosson. with reference to wheat origin

Dwarfing polish wheat is a dwarfing accession of Triticum polonicum L. from Xinjiang of China. In the present study, the artificial hybridization between dwarfing polish wheat and two accessions of Aegilops tauschii Cosson. (AS60 and AS65) was carried out, and the F₁ hybrids were obtained successfully without using embryo rescue techniques for the first time. The crossabilities of hybrids T. polonicum × Ae. tauschii (AS60) and T. polonicum × Ae. tauschii (AS65) were 1.67% and 0.60% respectively. Only the hybrids of T. polonicum × Ae. tauschii (AS60) germinated well, and 24 F₁ hybrid plants were obtained. All the F₁ hybrid plants grew vigorously, and the morphological traits were similar to bread wheat. The F₁ plants had some obvious traits inherited from T. polonicum and Ae. tauschii and were completely sterile. Chromosome pairing in the hybrid was characterized by a large number of univalents, with an average of 20.56 and 0.22 bivalents per PMC, and no ring bivalents and multivalents were observed. Furthermore, the potential value of the F1 hybrids between T. polonicum and Ae. tauschii for studying wheat origin and breeding are discussed. The article is published in the original.     

Identification of novel high molecular weight glutenin subunit mutants in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Bread wheat (Triticum aestivum L.) is a staple food crop eaten in different ways like pan and other food products. High molecular weight glutenin subunits (HMW-GS) are major determinants of the different wheat end-use qualities. Ethyl-methanesulfonate (EMS) mutagenized populations in plants can be used for the discovery of valuable mutants for basic research and breeding purposes. In this study, we report the identification of 27 HMW-GS M₃ mutants based on SDS-PAGE patterns from an EMS mutagenized population of the cultivar Baguette Premium 11. Nine mutations were detected in Ax2*, five in Bx7, four in By8, six in Dx5 and three in Dy10 subunit. Two Ax2* null mutants were characterized at molecular level finding in both cases premature stop codons associated. EMS would tend to generate more premature stop codons in glutenins genes than in others because these have a high frequency of glutamine codons. This type of mutation generates null alleles, therefore they are easily detectable by a low cost protocol like SDS-PAGE. The potential use of knock-out (null alleles) and SDS-PAGE size altered mutants for HMW-GS in wheat quality and nutrition is discussed.     

Genetic diversity analysis of abiotic stress response gene <Emphasis Type="Italic">TaSnRK2.7</Emphasis>-<Emphasis Type="Italic">A</Emphasis> in common wheat

Sucrose non-fermenting1-related protein kinase 2 (SnRK2) plays a key role in plant stress signaling transduction pathways. In this study, one copy of TaSnRK2.7, a SnRK2 member of common wheat, was isolated and characterized for nucleotide diversity among 45 wheat accessions with different stress-response features. Most of the accessions were elite wheat cultivars, which had been subject to population bottlenecks and intensive selection during breeding. Nucleotide and haplotype diversity across the entire TaSnRK2.7-A region was 0.00076 and 0.590, respectively, and diversity in non-coding regions was higher than that in coding regions. Sliding-window analysis showed variable levels of nucleotide variation along the entire TaSnRK2.7-A region; the sixth intron and ninth exon represented variation-enriched regions. As predicted, neutrality tests revealed that population bottlenecks or purifying selection had acted on the TaSnRK2.7-A gene, a relatively conserved gene. Furthermore, strong linkage disequilibrium between SNP loci extends across the entire TaSnRK2.7-A region. These findings demonstrate that the TaSnRK2.7-A genomic region has evolved under extensive selection pressure during crop breeding.     

Biological synthesis of quercetin 3-<Emphasis Type="Italic">O</Emphasis>-<Emphasis Type="Italic">N</Emphasis>-acetylglucosamine conjugate using engineered <Emphasis Type="Italic">Escherichia coli</Emphasis> expressing <Emphasis Type="Italic">UGT78D2</Emphasis>

Biotransformation of flavonoids using Escherichia coli harboring nucleotide sugar-dependent uridine diphosphate-dependent glycosyltransferases (UGTs) commonly results in the production of a glucose conjugate because most UGTs are specific for UDP-glucose. The Arabidopsis enzyme AtUGT78D2 prefers UDP-glucose as a sugar donor and quercetin as a sugar acceptor. However, in vitro, AtUGT78D2 could use UDP-N-acetylglucosamine as a sugar donor, and whole cell biotransformation of quercetin using E. coli harboring AtUGT78D2 produced quercetin 3-O-N-acetylglucosamine. In order to increase the production of quercetin 3-O-N-acetylglucosamine via biotransformation, two E. coli mutant strains deleted in phosphoglucomutase (pgm) or glucose-1-phosphate uridylyltransferase (galU) were created. The galU mutant produced up to threefold more quercetin 3-O-N-acetylglucosamine than wild type, resulting in the production of 380-mg/l quercetin 3-O-N-acetylglucosamine and a negligible amount of quercetin 3-O-glucoside. These results show that construction of bacterial strains for the synthesis of unnatural flavonoid glycosides is possible through rational selection of the nucleotide sugar-dependent glycosyltransferase and engineering of the nucleotide sugar metabolic pathway in the host strain.     

Molecular characterization of HMW glutenin subunit allele <Emphasis Type="Italic">1Bx14</Emphasis>: further insights into the evolution of <Emphasis Type="Italic">Glu-B1-1</Emphasis> alleles in wheat and related species

1Bx14 is a member of the high molecular weight (HMW) glutenin subunits specified by wheat Glu-B1-1 alleles. In this work, we found that the full-length amino acid sequence of 1Bx14 derived from cloned coding region was similar, but not identical, to that of 1Bx20. In the N-terminal domains of 1Bx14 and 1Bx20, the last two of the three cysteine residues, which are conserved in 1Bx7, 1Bx17 and homoeologous 1Ax and 1Dx subunits, were replaced by tyrosine residues. In the 5 flanking regions (–900 to –1,200 bp relative to the start codon), a novel miniature inverted-repeat transposable element insertion was present in 1Bx14 and 1Bx20 but not 1Bx7 and 1Bx17. 1Bx14 and 1Bx20 like alleles were readily found in tetraploid wheat subspecies but not several S genome containing Aegilops species. Phylogenetic analysis showed that the four molecularly characterized Glu-B1-1 alleles (1Bx7, 1Bx14, 1Bx17, 1Bx20) could be divided into two allelic lineages. The lineage represented by 1Bx7 and 1Bx17 was more ancient than the one represented by 1Bx14 and 1Bx20. Combined, our data establish that 1Bx14 and 1Bx20 represent a novel subclass of Glu-B1-1 alleles. Based on current knowledge, potential mechanism involved in the differentiation of two Glu-B1-1 lineages is discussed.Electronic Supplementary Material Supplementary material is available for this article at     

<Emphasis Type="Italic">egl</Emphasis>-<Emphasis Type="Italic">4</Emphasis> modulates electroconvulsive seizure duration in <Emphasis Type="Italic">C. elegans</Emphasis>

Increased neuronal excitability causes seizures with debilitating symptoms. Effective and noninvasive treatments are limited for easing symptoms, partially due to the complexity of the disorder and lack of knowledge of specific molecular faults. An unexplored, novel target for seizure therapeutics is the cGMP/protein kinase G (PKG) pathway, which targets downstream K⁺ channels, a mechanism similar to Retigabine, a recently FDA-approved antiepileptic drug. Our results demonstrate that increased PKG activity decreased seizure duration in C. elegans utilizing a recently developed electroconvulsive seizure assay. While the fly is a well-established seizure model, C. elegans are an ideal yet unexploited model which easily uptakes drugs and can be utilized for high-throughput screens. In this study, we show that treating the worms with either a potassium channel opener, Retigabine or published pharmaceuticals that increase PKG activity, significantly reduces seizure recovery times. Our results suggest that PKG signaling modulates downstream K⁺ channel conductance to control seizure recovery time in C. elegans. Hence, we provide powerful evidence, suggesting that pharmacological manipulation of the PKG signaling cascade may control seizure duration across phyla.     

Genetic mapping of a novel recessive allele for non-glaucousness in wild diploid wheat <Emphasis Type="Italic">Aegilops tauschii</Emphasis>: implications for the evolution of common wheat

Cuticular wax on the aerial surface of plants has a protective function against many environmental stresses. The bluish–whitish appearance of wheat leaves and stems is called glaucousness. Most modern cultivars of polyploid wheat species exhibit the glaucous phenotype, while in a wild wheat progenitor, Ae. tauschii, both glaucous and non-glaucous accessions exist. Iw2, a wax inhibitor locus on the short arm of chromosome 2D, is the main contributor to this phenotypic variation in Ae. tauschii, and the glaucous/non-glaucous phenotype of Ae. tauschii is usually inherited by synthetic hexaploid wheat. However, a few synthetic lines show the glaucous phenotype although the parental Ae. tauschii accessions are non-glaucous. Molecular marker genotypes indicate that the exceptional non-glaucous Ae. tauschii accessions share the same genotype in the Iw2 chromosomal region as glaucous accessions, suggesting that these accessions have a different causal locus for their phenotype. This locus was assigned to the long arm of chromosome 3D using an F₂ mapping population and designated W4, a novel glaucous locus in Ae. tauschii. The dominant W4 allele confers glaucousness, consistent with phenotypic observation of Ae. tauschii accessions and the derived synthetic lines. These results implied that glaucous accessions of Ae. tauschii with the W2W2iw2iw2W4W4 genotype could have been the D-genome donor of common wheat.