Characterization of novel microsatellite markers in Musa acuminata subsp. burmannicoides, var. Calcutta 4

<p>Abstract</p> <p>Background</p> <p>Banana is a nutritionally important crop across tropical and sub-tropical countries in sub-Saharan Africa, Central and South America and Asia. Although cultivars have evolved from diploid, triploid and tetraploid wild Asian species of <it>Musa acuminata </it>(A genome) and <it>Musa balbisiana </it>(B genome), many of today's commercial cultivars are sterile triploids or diploids, with fruit developing via parthenocarpy. As a result of restricted genetic variation, improvement has been limited, resulting in a crop frequently lacking resistance to pests and disease. Considering the importance of molecular tools to facilitate development of disease resistant genotypes, the objectives of this study were to develop polymorphic microsatellite markers from BAC clone sequences for <it>M. acuminata </it>subsp. <it>burmannicoides</it>, var. Calcutta 4. This wild diploid species is used as a donor cultivar in breeding programs as a source of resistance to diverse biotic stresses.</p> <p>Findings</p> <p>Microsatellite sequences were identified from five Calcutta 4 BAC consensi datasets. Specific primers were designed for 41 loci. Isolated di-nucleotide repeat motifs were the most abundant, followed by tri-nucleotides. From 33 tested loci, 20 displayed polymorphism when screened across 21 diploid <it>M. acuminata </it>accessions, contrasting in resistance to Sigatoka diseases. The number of alleles per SSR locus ranged from two to four, with a total of 56. Six repeat classes were identified, with di-nucleotides the most abundant. Expected heterozygosity values for polymorphic markers ranged from 0.31 to 0.75.</p> <p>Conclusions</p> <p>This is the first report identifying polymorphic microsatellite markers from <it>M. acuminata </it>subsp. <it>burmannicoides</it>, var. Calcutta 4 across accessions contrasting in resistance to Sigatoka diseases. These BAC-derived polymorphic microsatellite markers are a useful resource for banana, applicable for genetic map development, germplasm characterization, evolutionary studies and marker assisted selection for traits.</p

Efeitos da gessagem e da adubação boratada sobre os componentes de produção da cultura do amendoim.

CONTEÚDO: O cultivo do amendoim normalmente é realizado em áreas de renovação de canavial, cujos solos comumente apresentam-se exauridos após os sucessivos cortes de cana, sendo que a exaustão é mais intensa em solos arenosos tropicais, acarretando em baixos teores de cátions básicos (Ca) e micronutrientes (B). Nesse contexto, o objetivo deste trabalho foi avaliar os efeitos da gessagem e da adubação boratada sobre os componentes de produção da cultura do amendoim. O delineamento experimental foi em blocos ao acaso, com os tratamentos arranjados em parcelas subdivididas, nas parcelas foram realizadas gessagem em superfície na quantidade de 0; 0,5; 1,0 e 2,0 Mgha-1, e nas sub-parcelas foram realizadas pulverizações foliares com 0; N0,5; 1,0 e 2,0 kg ha-1 de B com a fonte ácido bórico. Aos 122 dias após a semeadura no estádio de maturação fisiológica dos grãos foi avaliada a produtividade de vagens e de grãos, o rendimento (%), número de vagens por planta, número de grãos por vagem e massa de 100 grãos. Não houve efeitos significativos da aplicação de gesso agrícola em superfície sobre os componentes de produção do amendoim. A adubação boratada promoveu incrementos sobre o número de vagens por planta, produtividade de vagens e produtividade de grãos, sendo que os melhores desempenhos produtivos do amendoim se deram com as doses entre 1,0 e 1,1 kg ha-1 de B. ABSTRACT: The cultivation of peanut is usually carried out in sugarcane renovation area, where soils commonly present depleted after successive sugarcane cultivation and the exhaust is more intense in tropical sandy soils, resulting in low basic cations (Ca) and micronutrients (B) . In this context, the aim of this study was to evaluate the effects of gypsum and fertilization with boron on yield components of peanut. The experimental design was a randomized block, with treatments arranged in split-Plot, the plots were made gypsum surface in the amount of 0; 0.5; 1.0 and 2.0 ton ha-1, and the subplot foliar applications of boron, in doses of 0; 0.5; 1.0 and 2.0 kg ha-1. At 122 days after sowing in the physiological maturity of the grains were evaluated pod yield and grain yield, percentage of yield, number of pods per plant, number of seeds per pod and weight of 100 grains. There were no significant effects of the application of gypsum surface on peanut yield components, already borated fertilization promoted increases on the number of pods per plant, pod yield and grain yield, and the best productive performance of peanut was given at doses between 1. 0 and 1. 1 kg ha-1 B

Genetic diversity of carotenoid-rich bananas evaluated by Diversity Arrays Technology (DArT)

The aim of this work was to evaluate the carotenoid content and genetic variability of banana accessions from the Musa germplasm collection held at Embrapa Cassava and Tropical Fruits, Brazil. Forty-two samples were analyzed, including 21 diploids, 19 triploids and two tetraploids. The carotenoid content was analyzed spectrophotometrically and genetic variability was estimated using 653 DArT markers. The average carotenoid content was 4.73 μg.g -1 , and ranged from 1.06 μg.g -1 for the triploid Nanica (Cavendish group) to 19.24 μg.g -1 for the triploid Saney. The diploids Modok Gier and NBA-14 and the triploid Saney had a carotenoid content that was, respectively, 7-fold, 6-fold and 9-fold greater than that of cultivars from the Cavendish group (2.19 μg.g -1). The mean similarity among the 42 accessions was 0.63 (range: 0.24 to 1.00). DArT analysis revealed extensive genetic variability in accessions from the Embrapa Musa germplasm bank