Samarium iodide-promoted asymmetric Reformatsky reaction of 3-(2-Haloacyl)-2-oxazolidinones with enals

3-(2-Haloacyl)-2-oxazolidinones were shown to react with enals in an asymmetric SmI2-promoted Reformatsky reaction to give stereochemically well-defined 3-hydroxy-4-alkenyl- and 3-hydroxy-2-methyl-4-alkenyl imides. Chirality transfer of the Evans (S)-oxazolidinone unit via a Zimmerman-Traxler-like transition state resulted in Reformatsky products with a relative syn-configuration. The absolute configuration of compounds obtained is opposite to the corresponding products obtained via aldol addition of boron enolates to enals using the same Evans oxazolidinones

Genetic structure, diversity, and allelic richness in composite collection and reference set in chickpea (Cicer arietinum L.)

<p>Abstract</p> <p>Background</p> <p>Plant genetic resources (PGR) are the basic raw materials for future genetic progress and an insurance against unforeseen threats to agricultural production. An extensive characterization of PGR provides an opportunity to dissect structure, mine allelic variations, and identify diverse accessions for crop improvement. The Generation Challenge Program <url>http://www.generationcp.org</url> conceptualized the development of "composite collections" and extraction of "reference sets" from these for more efficient tapping of global crop-related genetic resources. In this study, we report the genetic structure, diversity and allelic richness in a composite collection of chickpea using SSR markers, and formation of a reference set of 300 accessions.</p> <p>Results</p> <p>The 48 SSR markers detected 1683 alleles in 2915 accessions, of which, 935 were considered rare, 720 common and 28 most frequent. The alleles per locus ranged from 14 to 67, averaged 35, and the polymorphic information content was from 0.467 to 0.974, averaged 0.854. Marker polymorphism varied between groups of accessions in the composite collection and reference set. A number of group-specific alleles were detected: 104 in Kabuli, 297 in desi, and 69 in wild <it>Cicer</it>; 114 each in Mediterranean and West Asia (WA), 117 in South and South East Asia (SSEA), and 10 in African region accessions. Desi and kabuli shared 436 alleles, while wild <it>Cicer </it>shared 17 and 16 alleles with desi and kabuli, respectively. The accessions from SSEA and WA shared 74 alleles, while those from Mediterranean 38 and 33 alleles with WA and SSEA, respectively. Desi chickpea contained a higher proportion of rare alleles (53%) than kabuli (46%), while wild <it>Cicer </it>accessions were devoid of rare alleles. A genotype-based reference set captured 1315 (78%) of the 1683 composite collection alleles of which 463 were rare, 826 common, and 26 the most frequent alleles. The neighbour-joining tree diagram of this reference set represents diversity from all directions of the tree diagram of the composite collection.</p> <p>Conclusion</p> <p>The genotype-based reference set, reported here, is an ideal set of germplasm for allele mining, association genetics, mapping and cloning gene(s), and in applied breeding for the development of broad-based elite breeding lines/cultivars with superior yield and enhanced adaptation to diverse environments.</p

Diversity and gaps in Pennisetum glaucum subsp. monodii (Maire) Br. germplasm conserved at the ICRISAT genebank

The International Crops Research Institute for the Semi-Arid Tropics conserves 335 accessions of Pennisetum glaucum subsp. monodii originated in 13 countries. In the present study, the collection was evaluated and assessed for diversity and geographical gaps. A wide variation was observed in the collection for total tillers per plant (16 to 609), productive tillers per plant (12 to 368), leaf length (21.3 to 58.8 cm) and leaf width (8.1 to 33.1 mm), indicating high fodder yield potential of the collection. The accessions of cluster 3 flowered late, grew tall with thick stems and long and broad leaves, and differed significantly from those of cluster 1 and cluster 2. The accessions of cluster 2 were found to be promising for tillering. The highly significant positive correlation (r= 0.944) between total and productive tillers per plant suggests that the selection for total tillers will result in selection for productive tillers. A total of 354 districts located in 86 provinces of eight countries in the primary centre of origin for pearl millet were identified as geographical gaps. The probability map generated using FloraMap in the present study matched quite closely to the origin of pearl millet, supporting the prediction of P. glaucum subsp. monodii occurrence in the primary centre of diversity for pearl millet. The high fodder yield potential of P. glaucum subsp. monodii germplasm and low intensity of collection in countries under study suggest the need for launching germplasm collection missions, exclusively for pearl millet wild relatives to fill taxonomic and geographical gaps in the collection

Diversity and geographical gaps in Cajanus scarabaeoides (L.) Thou. germplasm conserved at the ICRISAT genebank

Crop wild relatives are important components of agro-ecosystems as potential gene contributors for crop improvement programmes. Cajanus scarabaeoides (L.) Thou., a pigeonpea wild relative is crossable with cultivated pigeonpea and possesses several beneficial traits. Hundred accessions conserved at the ICRISAT genebank were characterized for 13 quantitative and ten qualitative traits to assess the diversity in the collection. Highly significant genotypic variance for leaflet length, days to 5% maturity, seeds per pod, 100-seed weight, seed protein content and trichome density and length was observed. All C. scarabaeoides accessions used in the present study are the best sources for extra early ( 75%) map identified a total of 118 provinces covering 790 districts in Bangladesh, Cambodia, India, Indonesia, Laos, Malaysia, Myanmar, Nepal, Papua New Guinea, Philippines, Thailand and Vietnam as geographical gaps in the collection. Complete passport data including location coordinates should be collected while collecting the germplasm to analyze the spatial aspects of species distribution

Functionally Relevant Microsatellite Markers From Chickpea Transcription Factor Genes for Efficient Genotyping Applications and Trait Association Mapping

We developed 1108 transcription factor gene-derived microsatellite (TFGMS) and 161 transcription factor functional domain-associated microsatellite (TFFDMS) markers from 707 TFs of chickpea. The robust amplification efficiency (96.5%) and high intra-specific polymorphic potential (34%) detected by markers suggest their immense utilities in efficient large-scale genotyping applications, including construction of both physical and functional transcript maps and understanding population structure. Candidate gene-based association analysis revealed strong genetic association of TFFDMS markers with three major seed and pod traits. Further, TFGMS markers in the 5′ untranslated regions of TF genes showing differential expression during seed development had higher trait association potential. The significance of TFFDMS markers was demonstrated by correlating their allelic variation with amino acid sequence expansion/contraction in the functional domain and alteration of secondary protein structure encoded by genes. The seed weight-associated markers were validated through traditional bi-parental genetic mapping. The determination of gene-specific linkage disequilibrium (LD) patterns in desi and kabuli based on single nucleotide polymorphism-microsatellite marker haplotypes revealed extended LD decay, enhanced LD resolution and trait association potential of genes. The evolutionary history of a strong seed-size/weight-associated TF based on natural variation and haplotype sharing among desi, kabuli and wild unravelled useful information having implication for seed-size trait evolution during chickpea domestication

MODEM: a comprehensive approach to modelling outcome and costs impacts of interventions for dementia. Protocol paper

Background The MODEM project (A comprehensive approach to MODelling outcome and costs impacts of interventions for DEMentia) explores how changes in arrangements for the future treatment and care of people living with dementia, and support for family and other unpaid carers, could result in better outcomes and more efficient use of resources. Methods MODEM starts with a systematic mapping of the literature on effective and (potentially) cost-effective interventions in dementia care. Those findings, as well as data from a cohort, will then be used to model the quality of life and cost impacts of making these evidence-based interventions more widely available in England over the period from now to 2040. Modelling will use a suite of models, combining microsimulation and macrosimulation methods, modelling the costs and outcomes of care, both for an individual over the life-course from the point of dementia diagnosis, and for individuals and England as a whole in a particular year. Project outputs will include an online Dementia Evidence Toolkit, making evidence summaries and a literature database available free to anyone, papers in academic journals and other written outputs, and a MODEM Legacy Model, which will enable local commissioners of services to apply the model to their own populations. Discussion Modelling the effects of evidence-based cost-effective interventions and making this information widely available has the potential to improve the health and quality of life both of people with dementia and their carers, while ensuring that resources are used efficiently

An efficient and cost-effective approach for genic microsatellite marker-based large-scale trait association mapping: identification of candidate genes for seed weight in chickpea

The large-scale validation and high-throughput genotyping of numerous informative genic microsatellite markers are required for association mapping to identify candidate genes for complex quantitative traits in chickpea. However, the screening and genotyping of such informative markers in individual genotypes/whole association panels for trait association mapping involves massive costs in terms of resources, time and labour due to low genetic polymorphism in chickpea. We have developed an alternative time-saving and cost-effective pool-based trait association mapping approach by combining pooled DNA analysis (with 616 genic microsatellite markers) and individual genotype (large structured association panel) genotyping. Using this approach we have identified seven seed weight-associated transcription factor gene-derived microsatellite markers (with minor allele frequency >15 %) in desi and kabuli chickpea. Strong marker allele effects of these five transcription factors with increasing seed weight in the contrasting desi and kabuli genotypes were evident. Bi-parental linkage mapping using 241 of the informative gene-based microsatellite markers resulted in the identification and mapping of nine such markers linked with three major quantitative trait loci (explaining a total phenotypic variance of 23.5–34.7 %) on chromosomes 1 (CaqSW1.1: 73.5–74.5 cM and CaqSW1.2: 79.3–81.3 cM) and 2 (CaqSW2.1: 65.7–67.5 cM) controlling 100-seed weight in chickpea. The integration of pool-based trait association mapping with differential expression profiling, traditional bi-parental linkage mapping and high-resolution microsatellite-single nucleotide polymorphism marker-based haplotyping/linkage disequilibrium mapping delineated four transcription factor genes (DUF3594, bZIP, DUF1635 and SBP) controlling seed weight in desi and kabuli chickpea. The strategies implemented in our study can be used in large-scale trait association mapping for the rapid identification of candidate genes and in the development of functional markers for traits of agricultural importance in crop species including chickpea

Relationships between Transpiration Efficiency and Carbon Isotope Discrimination in Chickpea (C. arietinum L)

Since major cultivation areas of chickpea (Cicer arietinum L.) are in the arid and semi-arid zones, terminal drought is one of the major constraints limiting its productivity. Simple analytical crop models can help in identifying key strategies to improve the chickpea productivity under drought. For example, Passioura (1977) had proposed that the yield is a function of transpiration, transpiration efficiency (TE) defined as the biomass production per unit of water transpired, and harvest index. As improvement of TE means maximization of crop production per unit of water use, it is one of the important components for improving the drought resistance (Turner et al. 2001). Although TE had been recognized as a highly relevant trait, so far very little research effort had been made towards field screening for it, especially due to the difficulties in measuring TE in any screening method. The method developed by Farquhar et al. (1982) for estimating TE through measuring the discrimination against 13C by leaves during photosynthesis, and establishment of a close relationship between the carbon isotope discrimination (δ13C) and TE in many legume crops such as bean, cowpea, groundnut, and soybean has provided an useful method of screening. This gave scope for using δ13C as an indirect screening tool for TE. In chickpea, however, there is no information available on the relationship between δ13C and TE. The major objectives of this study were to check if there are any variations available for δ13C, to investigate the relationship between δ13C and TE, and to ascertain the possibility of using δ13C as a surrogate for TE measurements

Development of a composite collection for mining germplasm possessing allelic variation for beneficial traits in chickpea

Chickpea is one of the most important grain legume crops in the world. Large collections of genetic resources are maintained in the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and International Center for Agricultural Research in the Dry Areas (ICARDA) genebanks. Association mapping using neutral markers has been suggested as a means to identify useful alleles in the vast reservoirs of genetic diversity existing in the germplasm collections that could be associated with the phenotypes among the population individuals. ICRISAT in collaboration with ICARDA developed a global composite collection of 3000 accessions that will be profiled using 50 polymorphic simple sequence repeat (SSR) markers. The data generated through this collaborative effort will be used to define the genetic structure of the global composite collection and to select a reference sample of 300 accessions representing the maximum diversity for the isolation of allelic variants of candidate gene associated with beneficial traits. It is then expected that molecular biologists and plant breeders will have opportunities to use diverse lines in functional and comparative genomics, in mapping and cloning gene(s), and in applied plant breeding to diversify the genetic base of the breeding populations which should lead to the development of broad-based elite breeding lines/cultivars with superior yield and enhanced adaptation to diverse environments