Agradecimentos: This work was supported by grants from the Fundação de Amparo à Pesquisa de do Estado de São Paulo (FAPESP 05/51010-0; 08/52197-4), the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ), and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES – Computational Biology Programme). RF received Ph.D. fellowships from the CAPES-Embrapa Programme and the CAPES Computational Biology Programme and PD fellowship from FAPESP (2018/19219-6), and LL received a PD fellowship from the CAPES Computational Biology Programme. AG and AdS were recipients of a research fellowship from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). We would like to acknowledge the Brazilian Agricultural Research Corporation (Embrapa Beef Cattle) for providing the Urochloa decumbens progeny used in this study. We thank Aline da Costa Lima Moraes for the assistance in the GBS library construction and performing DNA sequencing Ver menos

Abstract: Urochloa decumbens (Stapf) R. D. Webster is one of the most important African forage grasses in Brazilian beef production. Currently available genetic-genomic resources for this species are restricted mainly due to polyploidy and apomixis. Therefore, crucial genomic-molecular studies such as the construction of genetic maps and the mapping of quantitative trait loci (QTLs) are very challenging and consequently affect the advancement of molecular breeding. The objectives of this work were to (i) construct an integrated U. decumbens genetic map for a full-sibling progeny using GBS-based markers with allele dosage information, (ii) detect QTLs for spittlebug (Notozulia entreriana) resistance, and (iii) seek putative candidate genes involved in defense against biotic stresses. We used the Setaria viridis genome a reference to align GBS reads and selected 4,240 high-quality SNP markers with allele dosage information. Of these markers, 1,000 were distributed throughout nine homologous groups with a cumulative map length of 1,335.09 cM and an average marker density of 1.33 cM. We detected QTLs for resistance to spittlebug, an important pasture insect pest, that explained between 4.66 and 6.24% of the phenotypic variation. These QTLs are in regions containing putative candidate genes related to defense against biotic stresses. Because this is the first genetic map with SNP autotetraploid dosage data and QTL detection in U. decumbens, it will be useful for future evolutionary studies, genome assembly, and other QTL analyses in Urochloa spp. Moreover, the results might facilitate the isolation of spittlebug-related candidate genes and help clarify the mechanism of spittlebug resistance. These approaches will improve selection efficiency and accuracy in U. decumbens molecular breeding and shorten the breeding cycle Ver menos