The Multigeneic _Rhg1_ Locus: A Model For The Effects on Root Development, Nematode Resistance and Recombination Suppression.

Soybean (Glycine max L. Merr.) resistance to populations (HgType) of _Heterodera glycines I._, the soybean cyst nematode (SCN), requires a functional allele at rhg1. An apoptosis-like response in the giant cells formed around the nematode results 24-48 h after feeding commences. This study aimed to identify the role of the three genes within the rhg1 locus, a receptor like kinase (RLK), a laccase and an ion anti-porter. Used were near isogeneic lines (NILs) that contrasted at their rhg1 alleles. Features of the rhg1 locus, the candidate genes and their nascent transcripts and proteins in roots were elucidated. First, evidence for a syntenic gene cluster was found and the effectiveness of SNP probes for distinguishing the homeolog sequence variant on linkage group (Lg) B1 from alleles at the rhg1 locus on Lg G was shown. Analysis of plant s heterozygous at rhg1 showed that the allele for resistance was dominant. The absence of recombination events among the NILs between the RLK and other 2 genes eliminated the possibility of a monogeneic rhg1 locus. Finally, an effect on root development was discovered. A model for multigeneic resistance based on developmental control of root growth including a mechanism for segregation distortion is presented

The persistence of open access electronic journals

Purpose – Open access (OA) electronic journals have been identified as potentially at risk of loss without more coordinated preservation efforts. The purpose of this paper is to test the current availability of OA electronic journals indexed in the Directory of Open Access Journals (DOAJ). Design/methodology/approach – Using publicly available journal metadata downloaded from DOAJ, individual journal URLs were tested for validity and accessibility using a Microsoft Excel Visual Basic for Applications macro. Findings – Initial results showed 69.51% of the URLs tested returned a successful HTTP status code. The remainder of the URLs returned codes that indicated redirection or errors. Originality/Value – Unlike past studies of link decay, this is not limited to cited references or a specific discipline. This study utilizes the full DOAJ metadata to analyze the persistence of OA electronic journals

A detailed study of streamer chambers

This thesis describes the construction and operation of a neon helium streamer chamber. The design of a fast high voltage pulsing system, which utilises the energy stored in a water dielectric capacitor and has been charged by a Marx generator, is discussed in detail. The performance of the system is examined and its characteristics are investigated particularly where they are relevant to its use as a particle detector. A statistical model has been programmed and is used to predict and interpret the results obtained directly from the streamer chamber. The agreement between theory and practice is found to be good. The spacial accuracy of the device is measured and its resolution estimated. No significant sensitivity to ionisation has been found but a time resolution of less than 1 µsec appears feasible. Suggestions to improve the streamer chamber system are made and proposals for a second generation streamer chamber are given

Soybean Genomics: Developments through the Use of Cultivar “Forrest”

Legume crops are particularly important due to their ability to support symbiotic nitrogen fixation, a key to sustainable crop production and reduced carbon emissions. Soybean (Glycine max) has a special position as a major source of increased protein and oil production in the common grass-legume rotation. The cultivar “Forrest” has saved US growers billions of dollars in crop losses due to resistances programmed into the genome. Moreover, since Forrest grows well in the north-south transition zone, breeders have used this cultivar as a bridge between the southern and northern US gene pools. Investment in Forrest genomics resulted in the development of the following research tools: (i) a genetic map, (ii) three RIL populations (96 > n > 975), (iii) ∼200 NILs, (iv) 115 220 BACs and BIBACs, (v) a physical map, (vi) 4 different minimum tiling path (MTP) sets, (vii) 25 123 BAC end sequences (BESs) that encompass 18.5 Mbp spaced out from the MTPs, and 2 000 microsatellite markers within them (viii) a map of 2408 regions each found at a single position in the genome and 2104 regions found in 2 or 4 similar copies at different genomic locations (each of >150 kbp), (ix) a map of homoeologous regions among both sets of regions, (x) a set of transcript abundance measurements that address biotic stress resistance, (xi) methods for transformation, (xii) methods for RNAi, (xiii) a TILLING resource for directed mutant isolation, and (xiv) analyses of conserved synteny with other sequenced genomes. The SoyGD portal at sprovides access to the data. To date these resources assisted in the genomic analysis of soybean nodulation and disease resistance. This review summarizes the resources and their uses

Assessment of Genetic Biodiversity of Several Traits Using SSR Markers in Rice (Oryza sativa L.)

Eight primers (RM 315, RM 318, RM 166, RM 302, RM 201, RM 234, RM 526 and RM 144) revealed different levels of polymorphism to tag the related traits of interest as tolerant to abiotic stress, resistant to biotic stress and yield-related traits. Two primers (RM 190 and RM 278) were monomorphic. The percentage of the polymorphism was nearly 80 %. The size of detected fragments ranged from 105–325 bp. A total of 186 bands were scored from the amplification products with the ten SSR primers. Genetic diversity analyses were conducted on the basis of the scores with 176 unique bands. Phylogenic tree for the fifteen rice accessions from each group were established according to the molecular data and based on ten SSRs. A marked genetic diversity was observed in these innovative accessions (Sakha 101, IR 03N137, IR 83142-12, IR 87856-10-AJY-1-B, HHZ 12-Y4-DT1-Y2 and IR 1552), which revealed higher levels of diversity and hence can be used as donors for the effective conservation, utilization and providing favorable genes in rice breeding programs

Structural chemistry of layered lead halide perovskites containing single octahedral layers

Funding: Leverhulme Trust (award No. RPG-2018-065).We present a comprehensive review of the structural chemistry of hybrid lead halides of stoichiometry APbX4, A2PbX4 or AAʹPbX4, where A and Aʹ are organic ammonium cations and X = Cl, Br or I. These compounds may be considered as layered perovskites, containing isolated, infinite layers of corner-sharing PbX4 octahedra separated by the organic species. We first extract over 250 crystal structures from the CCDC and classify them in terms of unit cell metrics and crystal symmetry. Symmetry mode analysis is then used to identify the nature of key structural distortions of the [PbX4]∞ layers. Two generic types of distortion are prevalent in this family: tilting of the octahedral units and shifts of the inorganic layers relative to each other. Although the octahedral tilting modes are well-known in the crystallography of purely inorganic perovskites, the additional layer shift modes are shown to enrich enormously the structural options available in layered hybrid perovskites. Some examples and trends are discussed in more detail in order to show how the nature of the interlayer organic species can influence the overall structural architecture, although the main aim of the paper is to encourage workers in the field to make use of the systematic crystallographic methods used here to further understand and rationalise their own compounds, and perhaps to be able to design-in particular structural features in future work.Publisher PDFPeer reviewe

Complex octahedral tilt phases in the ferroelectric perovskite system LixNa1–xNbO3

We thank STFC for provision of neutron diffraction facilities at ISIS and Dr Aziz Daoud-Aladine for experimental assistance. CALD was supported by an EPSRC DTA studentship (EP/L50579/1).High-temperature phase behavior in the system LixNa1−xNbO3 has been studied by using high-resolution neutron powder diffraction. Each of the three compositions studied in the Na-rich part of the phase diagram (viz., x=0.03,0.08, and 0.12) shows evidence for distinct and complex structural modulations based on different tilting schemes of NbO6 octahedral units. Whilst octahedral tilting is prevalent in the structural chemistry of perovskites the details of the long-range tilt phases are distinct from those previously observed in NaNbO3 itself. A phase with a well-defined fourfold superlattice is observed for the composition Li0.12Na0.88NbO3, and yet more complex phases with modulations based on 20-fold and 30-fold repeats are observed for Li0.03Na0.97NbO3 and Li0.08Na0.92NbO3, respectively. This peculiar structural frustration makes the system LixNa1−xNbO3 a most structurally complex “simple” perovskite.PostprintPostprintPeer reviewe

Review of the Rpt3 Genes Encoding Part of the 26S Proteasome Associated with Loci Underlying Disease Resistance in Soybean

The 26S proteasomal complex is a multifunctional proteolytic machinery of the cell. The proteasome plays role in myriad of cellular functions, which have been further diversified by its separable proteolytic and non-proteolytic sub-complexes. Protein quality control and turnover, cell cycle regulation, gene regulation and DNA repair are among the key processes controlled by the proteasome. Disease resistance in plants invokes changes in all the processes controlled by the 26S proteasome. In this review, the potential contribution of genes encoding the proteasome to disease resistance in soybean (Glycine max L. Merr.) was examined

Using A Minimum Tile Path For Plant Transformations Encompassing the Entire Soybean Genome

Genomes like Glycine max (soybean) that have been highly conserved following increases in ploidy represent a frontier for genome analysis. Many soybean QTL analyzed to date have been composed of gene clusters each with contributing a portion of the trait rather than alleles of single genes. At the Soybean Genome Database (SoyGD) http://soybeangenome.siu.edu the genome browser that integrates and served the publicly available soybean physical map, BAC fingerprint database and genetic map associated genomic data shows a minimum tile of transformation ready BIBAC-like clones in pCLD04541 (pV41; oriV; tra; bom). Sequence resources made available through the DOE genome sequencing project have allowed the minimum tile to be revised and new functional analyses to be made. There are 3,840 MTP clones that appeared to encompass 90% of the genome (see http://soybeangenome.siu.edu/cgi-bin/gbrowse/BES_scaffolds). The BIBAC-like clones (tetR) from E. coli DH10 B were transferred en masse to Agrobacterium tumefaciens by triparental matings with EHA105 (rifR) mediated by pRK2013 (oriP) in DH10B (kanR) in 384 well plates. Although not necessary the extra helper plasmid boosted efficiency 10 fold. Individual A. tumefaciens rifampicin and tetracyclin resistant strains were used for transformation of Arabidopsis thaliana flowers in 384 well arrays. Initially kanamycin selection was used to isolate transgenic plants. Because the BACs were already tetR the recA mutants of A. tumefaciens could not be used (Tn3 insertions). Consequent to this and partial transconjugation events only some inserts are transferred completely while other transformed lines contain a substitution series of deleted inserts anchored on the Ti-left border (LB). These are maintained as kanR mixtures of seed. Phenotypes found for lines transgenic for particular BACs that were repeated include seed composition (protein, oil), development (growth, senescence) and disease resistance (suddean death syndrome (SDS) and soybean cyst nematode (SCN)

Infrared scintillation yield in gaseous and liquid argon

The study of primary and secondary scintillations in noble gases and liquids is of paramount importance to rare-event experiments using noble gas media. In the present work, the scintillation yield in gaseous and liquid Ar has for the first time been measured in the near infrared (NIR) and visible region, both for primary and secondary (proportional) scintillations, using Geiger-mode avalanche photodiodes (G-APDs) and pulsed X-ray irradiation. The primary scintillation yield of the fast component was measured to be 17000 photon/MeV in gaseous Ar in the NIR, in the range of 690-1000 nm, and 510 photon/MeV in liquid Ar, in the range of 400-1000 nm. Proportional NIR scintillations (electroluminescence) in gaseous Ar have been also observed; their amplification parameter at 163 K was measured to be 13 photons per drifting electron per kV. Possible applications of NIR scintillations in high energy physics experiments are discussed.Comment: 6 pages, 5 figures. Submitted to Europhysics Letter. Revised Figs. 3 and