160 research outputs found

    Identification of candidate genome regions controlling disease resistance in Arachis

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    <p>Abstract</p> <p>Background</p> <p>Worldwide, diseases are important reducers of peanut (<it>Arachis hypogaea</it>) yield. Sources of resistance against many diseases are available in cultivated peanut genotypes, although often not in farmer preferred varieties. Wild species generally harbor greater levels of resistance and even apparent immunity, although the linkage of agronomically un-adapted wild alleles with wild disease resistance genes is inevitable. Marker-assisted selection has the potential to facilitate the combination of both cultivated and wild resistance loci with agronomically adapted alleles. However, in peanut there is an almost complete lack of knowledge of the regions of the <it>Arachis </it>genome that control disease resistance.</p> <p>Results</p> <p>In this work we identified candidate genome regions that control disease resistance. For this we placed candidate disease resistance genes and QTLs against late leaf spot disease on the genetic map of the A-genome of <it>Arachis</it>, which is based on microsatellite markers and legume anchor markers. These marker types are transferable within the genus <it>Arachis </it>and to other legumes respectively, enabling this map to be aligned to other <it>Arachis </it>maps and to maps of other legume crops including those with sequenced genomes. In total, 34 sequence-confirmed candidate disease resistance genes and five QTLs were mapped.</p> <p>Conclusion</p> <p>Candidate genes and QTLs were distributed on all linkage groups except for the smallest, but the distribution was not even. Groupings of candidate genes and QTLs for late leaf spot resistance were apparent on the upper region of linkage group 4 and the lower region of linkage group 2, indicating that these regions are likely to control disease resistance.</p

    Acidentes de trabalho entre coletores de lixo de uma cidade interiorana do Estado de SĂŁo Paulo

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    The authors studied occupational accidents occurring among trash collectors in a city of SĂŁo Paulo state, between 1987 and 1988. The data were collected from analysis of the “Communications of Work Accidents” reported to the Health and Welfare Institute. A total of 137 accidents causing a loss of 1739 work days were reported. The workers suffered lesions of the upper and lower limbs caused by improper packaging of trash and the trash collection truck. Attention must be giver to trash collectors through simple measures and by the contracting of a nurse to look after care these injuries.Trata-se de estudo sobre acidentes de trabalho entre coletores de lixo de uma cidade do Estado de SĂŁo Paulo, entre 1987 e 1988. Como fonte de dados utilizou-se das notificaçoes das ComunicaçÔes de Acidentes de Trabalho efetuadas Empresa de Limpeza urbana Ă  PrevidĂȘncia Social. Verificou-se que 137 acidentes de trabalho ocasionaram perda de 1739 dias de serviço. Esses lesaram os trabalhadores em membros inferiores e superiores e foram casados pelo acondicionamento do lixo e caminhĂŁo coletor. Sugere-se que seja dada atenção aos trabalhadores atravĂ©s de medidas de carĂĄter simples e atravĂ©s da contratação de um enfermeiro do trabalho para assisti-los

    Harnessing Genetic Diversity of Wild Arachis Species for Genetic Enhancement of Cultivated Peanut

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    Peanut (Arachis hypogaea L.) is an important self-pollinating tetraploid (AABB, 2n = 4x = 40) legume grown for the high-quality edible oil and easily digestible protein in its seeds. Enormous genetic variability is present in the genus Arachis containing 79 wild species and cultivated peanut. Wild species offer significant variability, particularly for biotic and abiotic stresses, and can be used to develop cultivars with enhanced levels of resistance to key stresses. However, utilization of these species requires use of ploidy manipulations, bridge crosses, and embryo or ovule rescue. For efficient use of diploid wild species from section Arachis, several synthetics (amphidiploids and autotetraploids) have been developed using A- and B-genome accessions with high levels of resistance to multiple stresses. These synthetics are used in crossing programs with cultigens to develop prebreeding populations and introgression lines (ILs) with high frequency of useful genes and alleles into good agronomic backgrounds. Evaluation of two such populations derived from ICGV 91114 × ISATGR 121250 (a synthetic derived from A. duranensis Krapov. & W.C. Greg. × A. ipaensis Krapov. & W.C. Greg.) and ICGV 87846 × ISATGR 265-5 (A. kempf-mercadoi W.C. Greg. & C.E. Simpson × A. hoehnei Krapov. & W.C. Greg.) resulted in the identification of ILs with high levels of late leaf spot (LLS) and rust resistance and significant genetic variability for morphoagronomic traits. Genotyping of these ILs with markers linked to rust and LLS resistance provided evidence that introgression of possible novel alleles and resistance sources from different wild species other than the commonly used A. cardenasii Krapov. & W.C. Greg. will be beneficial for peanut improvement

    FIDEL—a retrovirus-like retrotransposon and its distinct evolutionary histories in the A- and B-genome components of cultivated peanut

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    In this paper, we describe a Ty3-gypsy retrotransposon from allotetraploid peanut (Arachis hypogaea) and its putative diploid ancestors Arachis duranensis (A-genome) and Arachis ipaënsis (B-genome). The consensus sequence is 11,223 bp. The element, named FIDEL (Fairly long Inter-Dispersed Euchromatic LTR retrotransposon), is more frequent in the A- than in the B-genome, with copy numbers of about 3,000 (±950, A. duranensis), 820 (±480, A. ipaënsis), and 3,900 (±1,500, A. hypogaea) per haploid genome. Phylogenetic analysis of reverse transcriptase sequences showed distinct evolution of FIDEL in the ancestor species. Fluorescent in situ hybridization revealed disperse distribution in euchromatin and absence from centromeres, telomeric regions, and the nucleolar organizer region. Using paired sequences from bacterial artificial chromosomes, we showed that elements appear less likely to insert near conserved ancestral genes than near the fast evolving disease resistance gene homologs. Within the Ty3-gypsy elements, FIDEL is most closely related with the Athila/Calypso group of retrovirus-like retrotransposons. Putative transmembrane domains were identified, supporting the presence of a vestigial envelope gene. The results emphasize the importance of FIDEL in the evolution and divergence of different Arachis genomes and also may serve as an example of the role of retrotransposons in the evolution of legume genomes in general
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