Upper Bounds for the Davenport Constant

We prove that for all but a certain number of abelian groups of order n its Davenport constant is atmost n/k+k-1 for k=1,2,..,7. For groups of order three we improve on the existing bound involving the Alon-Dubiner constant.Comment: article soumis, decembre 200

Highly informative genic and genomic SSR markers to facilitate molecular breeding in cultivated groundnut (Arachis hypogaea)

With an objective of identification of highly informative set of SSR markers in cultivated groundnut (Arachis hypogaea L.), a total of 4485 markers were used for screening using a set of 20 parental genotypes of 15 mapping populations. Although 3582 (79.9%) markers provided scorable amplification, only 1351 (37.3%) markers showed polymorphism. Polymorphism information content (PIC) value ranged from 0.10 (GM742) to 0.89 (S009) with an average of 0.31. Similarly, number of alleles ranged from 2 to 14 with an average of 3.2 alleles. In general, the SSR markers based on dinucleotide repeats displayed higher PIC value and number of alleles. Based on these polymorphism features, 199 markers with >0.50 PIC values have been identified. Polymorphism features of these markers along with the primer sequences, for the first time, for a total of 946 SSR markers have been provided. It is anticipated that the identified set of highly informative markers, instead of starting from the random set of SSR markers, should be very useful to initiate molecular genetics and breeding studies in cultivated groundnut

An International Reference Consensus Genetic Map with 897 Marker Loci Based on 11 Mapping Populations for Tetraploid Groundnut (Arachis hypogaea L.)

Only a few genetic maps based on recombinant inbred line (RIL) and backcross (BC) populations have been developed for tetraploid groundnut. The marker density, however, is not very satisfactory especially in the context of large genome size (2800 Mb/1C) and 20 linkage groups (LGs). Therefore, using marker segregation data for 10 RILs and one BC population from the international groundnut community, with the help of common markers across different populations, a reference consensus genetic map has been developed. This map is comprised of 897 marker loci including 895 simple sequence repeat (SSR) and 2 cleaved amplified polymorphic sequence (CAPS) loci distributed on 20 LGs (a01–a10 and b01–b10) spanning a map distance of 3, 863.6 cM with an average map density of 4.4 cM. The highest numbers of markers (70) were integrated on a01 and the least number of markers (21) on b09. The marker density, however, was lowest (6.4 cM) on a08 and highest (2.5 cM) on a01. The reference consensus map has been divided into 20 cM long 203 BINs. These BINs carry 1 (a10_02, a10_08 and a10_09) to 20 (a10_04) loci with an average of 4 marker loci per BIN. Although the polymorphism information content (PIC) value was available for 526 markers in 190 BINs, 36 and 111 BINs have at least one marker with >0.70 and >0.50 PIC values, respectively. This information will be useful for selecting highly informative and uniformly distributed markers for developing new genetic maps, background selection and diversity analysis...

Quantitative trait locus analysis and construction of consensus genetic map for drought tolerance traits based on three recombinant inbred line populations in cultivated groundnut (Arachis hypogaea L.)

Groundnut (Arachis hypogaea L.) is an important food and cash crop grown mainly in semi-arid tropics (SAT) regions of the world where drought is the major constraint on productivity. With the aim of understanding the genetic basis and identification of quantitative trait loci (QTL) for drought tolerance, two new recombinant inbred line (RIL) mapping populations, namely ICGS 76 × CSMG 84-1 (RIL-2) and ICGS 44 × ICGS 76 (RIL-3), were used. After screening of 3,215 simple sequence repeat (SSR) markers on the parental genotypes of these populations, two new genetic maps were developed with 119 (RIL-2) and 82 (RIL-3) SSR loci. Together with these maps and the reference map with 191 SSR loci based on TAG 24 × ICGV 86031 (RIL-1), a consensus map was constructed with 293 SSR loci distributed over 20 linkage groups, spanning 2,840.8 cM. As all these three populations segregate for drought-tolerance-related traits, a comprehensive QTL analysis identified 153 main effect QTL (M-QTL) and 25 epistatic QTL (E-QTL) for drought-tolerance-related traits. Localization of these QTL on the consensus map provided 16 genomic regions that contained 125 QTL. A few key genomic regions were selected on the basis of the QTL identified in each region, and their expected role in drought adaptation is also discussed. Given that no major QTL for drought adaptation were identified, novel breeding approaches such as marker-assisted recurrent selection (MARS) and genomic selection (GS) approaches are likely to be the preferred approaches for introgression of a larger number of QTL in order to breed drought-tolerant groundnut genotypes

Single Nucleotide Polymorphism–based Genetic Diversity in the Reference Set of Peanut (Arachis spp.) by Developing and Applying Cost-Effective Kompetitive Allele Specific Polymerase Chain Reaction Genotyping Assays

Kompetitive allele-specific polymerase chain reaction (KASP) assays have emerged as cost-effective marker assays especially for molecular breeding applications. Therefore, a set of 96 informative single nucleotide polymorphisms (SNPs) was used to develop KASP assays in groundnut or peanut (Arachis spp.). Developed assays were designated as groundnut KASP assay markers (GKAMs) and screened on 94 genotypes (validation set) that included parental lines of 27 mapping populations, seven synthetic autotetraploid and amphidiploid lines, and 19 wild species accessions. As a result, 90 GKAMs could be validated and 73 GKAMs showed polymorphism in the validation set. Validated GKAMs were screened on 280 diverse genotypes of the reference set for estimating diversity features and elucidating genetic relationships. Cluster analysis of marker allelic data grouped accessions according to their genome type, subspecies, and botanical variety. The subspecies Arachis hypogaea L. subsp. fastigiata Waldron and A. hypogaea subsp. hypogaea formed distinct cluster; however, some overlaps were found indicating their frequent intercrossing during the course of evolution. The wild species, having diploid genomes, were grouped into a single cluster. The average polymorphism information content value for polymorphic GKAMs was 0.32 in the validation set and 0.31 in the reference set. These validated and highly informative GKAMs may be useful for genetics and breeding applications in Arachis species

Genome-based trait prediction in multi- environment breeding trials in groundnut

Genomic selection (GS) can be an efficient and cost-effective breeding approach which captures both small- and large-effect genetic factors and therefore promises to achieve higher genetic gains for complex traits such as yield and oil content in groundnut. A training population was constituted with 340 elite lines followed by genotyping with 58 K ‘Axiom_Arachis’ SNP array and phenotyping for key agronomic traits at three locations in India. Four GS models were tested using three different random cross-validation schemes (CV0, CV1 and CV2). These models are: (1) model 1 (M1 = E + L) which includes the main effects of environment (E) and line (L); (2) model 2 (M2 = E + L + G) which includes the main effects of markers (G) in addition to E and L; (3) model 3 (M3 = E + L + G + GE), a naïve interaction model; and (4) model 4 (E + L + G + LE + GE), a naïve and informed interaction model. Prediction accuracy estimated for four models indicated clear advantage of the inclusion of marker information which was reflected in better prediction accuracy achieved with models M2, M3 and M4 as compared to M1 model. High prediction accuracies (> 0.600) were observed for days to 50% flowering, days to maturity, hundred seed weight, oleic acid, rust@90 days, rust@105 days and late leaf spot@90 days, while medium prediction accuracies (0.400–0.600) were obtained for pods/plant, shelling %, and total yield/plant. Assessment of comparative prediction accuracy for different GS models to perform selection for untested genotypes, and unobserved and unevaluated environments provided greater insights on potential application of GS breeding in groundnut

Novel set of groundnut SSR markers for germplasm analysis and interspecific transferability

Cultivated groundnut (Arachis hypogaea L.), is an important oil seed crop grown mostly in tropical and subtropical regions of the world. However, it suffers with narrow genetic diversity due to genetic bottlenecks such as the recent polyploidization and self pollinating nature of the crop. In such crop species, simple sequence repeats (SSRs), as compared to other marker systems such as restriction fragment length polymorphisms (RFLPs), randomly amplified polymorphic DNAs (RAPDs) and amplified fragment length polymorphisms (AFLPs) have been found more informative for genetic studies and breeding applications. Therefore, with an aim to develop new SSR markers in groundnut, a SSR-enriched library was constructed from the genotype ICGV 86031. Out of 29 SSRs isolated, primer pairs were designed for 23 SSR loci, of which 14 (61%) primer pairs yielded scorable amplicons. Eight (57%) primer pairs showed polymorphism among 23 groundnut genotypes that are parents of different groundnut mapping populations at ICRISAT, India and EMBRAPA, Brazil. The polymorphism information content (PIC) for polymorphic SSR markers ranged from 0.13 to 0.36, with an average of 0.25. Newly isolated SSR loci showed good interspecific transferability rates ranging from 13% to 100% across seven legumes and 43% to 100% within the seven legumes. The present set of newly developed SSR markers enriches the existing groundnut SSR repertoire and the transferable SSR markers will be useful for comparative genome analysis in related legumes

Novel set of groundnut SSR markers for germplasm analysis and interspecific transferability

Cultivated groundnut (Arachis hypogaea L.), is an important oil seed crop grown mostly in tropical and subtropical regions of the world. However, it suffers with narrow genetic diversity due to genetic bottlenecks such as the recent polyploidization and self pollinating nature of the crop. In such crop species, simple sequence repeats (SSRs), as compared to other marker systems such as restriction fragment length polymorphisms (RFLPs), randomly amplified polymorphic DNAs (RAPDs) and amplified fragment length polymorphisms (AFLPs) have been found more informative for genetic studies and breeding applications. Therefore, with an aim to develop new SSR markers in groundnut, a SSR-enriched library was constructed from the genotype ICGV 86031. Out of 29 SSRs isolated, primer pairs were designed for 23 SSR loci, of which 14 (61%) primer pairs yielded scorable amplicons. Eight (57%) primer pairs showed polymorphism among 23 groundnut genotypes that are parents of different groundnut mapping populations at ICRISAT, India and EMBRAPA, Brazil. The polymorphism information content (PIC) for polymorphic SSR markers ranged from 0.13 to 0.36, with an average of 0.25. Newly isolated SSR loci showed good interspecific transferability rates ranging from 13% to 100% across seven legumes and 43% to 100% within the seven legumes. The present set of newly developed SSR markers enriches the existing groundnut SSR repertoire and the transferable SSR markers will be useful for comparative genome analysis in related legumes

Periodontal health awareness and self-perceived halitosis among various professional students of West Godavari District of Andhra Pradesh

Introduction: Oral health is an essential part of maintaining overall health, and poor oral health can have a profound effect on the quality of life. Among the various sections of the population present in the society, professional students include a large group of population and are believed to have a better awareness pertaining to oral health than the common population. Aim: This study aims to determine the periodontal health awareness levels along with the self-perception of halitosis among the medical, pharmacy, and engineering students in the West Godavari district of Andhra Pradesh. Materials and Methods: A descriptive cross-sectional survey was conducted in 1230 students from medical, engineering, and pharmacy professions. A self-administered 27-item structured questionnaire was used to assess periodontal health and knowledge pertaining to oral hygiene practices along with the assessment of self-perceived halitosis. Tests of the association between self-perceived halitosis and the risk factors were conducted using Chi-square test. Intergroup comparison was conducted by ANOVA and t-test. Results: Self-perceived malodor reported was 50%, 54%, and 60% by medical, pharmacy, and engineering students, respectively. The difference in the levels of overall periodontal health awareness was statistically significant among the different specialities with the highest score gained by medical students (4.1 ± 2.0), followed by the pharmacy (2.9 ± 1.6), and engineering (1.6 ± 1.3) students. Conclusions: Even though professional students do have an acceptable level of knowledge regarding oral health, the level of awareness pertaining to periodontal health in particular is lacking. Hence, there is a need to extend the horizon for oral healthcare to other professional students at an elementary level