Abstract In plant breeding, the dialelic models univariate have aided the selection of parents for hybridization. Multivariate analyses allow combining and associating the multiple pieces of information of the genetic relationships between traits. Therefore, multivariate analyses might refine the discrimination and selection of the parents with greater potential to meet the goals of a plant breeding program. Here, we propose a method of multivariate analysis used for stablishing mega-traits (MTs) in diallel trials. The proposed model is applied in the evaluation of a multi-environment complete diallel trial with 90 F1’s of simple maize hybrids. From a set of 14 traits, we demonstrated how establishing and interpreting MTs with agronomic implication. The diallel analyzes based on mega-traits present an important evolution in statistical procedures since the selection is based on several traits. We believe that the proposed method fills an important gap of plant breeding. In our example, three MTs were established. The first, formed by plant stature-related traits, the second by tassel size-related traits, and the third by grain yield-related traits. Individual and joint diallel analysis using the established MTs allowed identifying the best hybrid combinations for achieving F1’s with lower plant stature, tassel size, and higher grain yield.

No Sul do Brasil são cultivadas variedades locais das cinco espécies domesticadas de Cucurbita. Dentre elas, as menos estudadas são C. argyrosperma e C. ficifolia. Análises de microssatélites são importantes para a caracterização molecular dessas duas espécies, mas existe a necessidade de primers específicos, ainda não disponíveis. O objetivo desse trabalho foi avaliar a transferibilidade de primers e otimizar a amplificação de locos SSR de C. pepo em C. argyrosperma e C. ficifolia, bem como averiguar a diversidade genética entre diferentes acessos de germoplasma destas espécies. Foram utilizados dez acessos de C. pepo, nove de C. argyrosperma e cinco de C. ficifolia do Banco Ativo de Germoplasma de Cucurbitáceas da Embrapa Clima Temperado. O DNA foi extraído em bulk das folhas de cinco indivíduos de cada acesso. Foram usados 40 primers SSR desenvolvidos para C. pepo. Em C. pepo, 35 primers (87,5%) amplificaram, em C. argyrosperma, 34 primers (85%) e em C. ficifolia, 32 primers (80%). Portanto a taxa de transferibilidade de locos SSR de C. pepo para C. argyrosperma e C. ficifolia foi alta, indicando que podem ser empregados na caracterização molecular destas espécies.

Landraces of five domesticated species of Cucurbita are cultivated in southern Brazil. Among them C. argyrosperma and C. ficifolia are the least studied. Microsatellite markers are important for the molecular characterization of these two species, but there is a need for specific primers, not yet available. The aim of this study was to evaluate the transferability of primers and optimize the amplification of SSR loci in C. pepo, C. argyrosperma and C. ficifolia and also evaluate genetic diversity in different accessions of germplasm in these species. We used ten accessions of C. pepo, nine of C. argyrosperma and five of C. ficifolia from the Genebank of Cucurbitaceae from Embrapa Temperate Agriculture. DNA was extracted in bulk from the leaves of five individuals of each accession. 40 SSR primers developed for C. pepo were used. In C. pepo 35 primers (87.5%) amplified, in C. argyrosperma, 34 primers (85%), and in C. ficifolia, 32 primers (80%). The transferability of SSR loci in C. pepo to C. argyrosperma and C. ficifolia was 85 and 80% respectively. The transferability of SSR loci from C. pepo to C. argyrosperma and C. ficifolia was 85 and 80% respectively. Thus, the transferability rate of SSR loci developed for C. pepo to C. argyrosperma and C. ficifolia was high, indicating that they can be used in molecular characterization of these species.

Dentre as cinco espécies de abóboras domesticadas, Cucurbita pepo apresenta a maior variabilidade para características de fruto, como cor, formato e tamanho. O Banco Ativo de Germoplasma de Cucurbitáceas da Embrapa Clima Temperado conta com 61 acessos desta espécie, todos estes, variedades crioulas cultivadas no sul do Brasil. Estas variedades crioulas fazem parte da cultura regional, na gastronomia, no artesanato e na ornamentação de ambientes. O objetivo deste trabalho foi avaliar a variabilidade genética entre e dentro de variedades crioulas de C. pepo cultivadas no Rio Grande do Sul, utilizando marcadores microssatélites. Foram avaliados 10 acessos de variedades crioulas de C. pepo. que apresentavam diferentes formatos e tamanhos de fruto, cores e texturas da casca. O DNA genômico foi extraído individualmente de cinco plantas de cada acesso. Foram analisados 40 locos de microssatélites. Destes, 34 amplificaram, identificando 100 alelos (variação de um a cinco alelos por loco). Dos locos analisados 85,3% foram polimórficos, evidenciando a variabilidade genética entre os acessos. A análise molecular da variância mostrou que 45,39% da variabilidade genética é atribuída à variação dentro dos acessos e 54,60% a diferenças entre acessos. Assim, apesar de haver variabilidade genética dentro dos acessos, a maior proporção da variabilidade em C. pepo encontra-se distribuída entre as diferentes variedades crioulas. A variação dentro dos acessos é explicada pela alogamia da espécie, pelo intercâmbio de sementes das variedades crioulas entre os agricultores e também pelos mesmos cultivarem mais de uma variedade de Cucurbita na mesma área.

Among the five cultivated species of pumpkins, Cucurbita pepo has the highest variability for fruit characteristics, such as color, shape and size. The Active Germplasm Bank of Cucurbitaceae from Embrapa Clima Temperado (Brazil) has 61 accessions of this species, all of them landraces grown in southern Brazil. These landraces are part of regional culture, in gastronomy (preparation of traditional dishes) for crafts and ornaments. The aim of this study was to evaluate genetic variability within and among landraces of C. pepo cultivated in Rio Grande do Sul state, by microsatellite markers. Ten accessions of C. pepo landraces with different shapes and sizes of fruit, and colors and textures of fruit skin were evaluated. Genomic DNA was extracted individually from five plants of each accession. Forty microsatellite loci were analyzed, and 34 amplified. In total 100 alleles were found (one to five alleles per locus). From the analysed loci, 85.3% were polymorphic, showing the presence of genetic variability among the accessions. The analysis of molecular variance showed that 45.39% of genetic variability is attributed to differences within accessions, and 54.60% is attributable to variation among accessions. Thus, despite the presence of genetic variability within accessions, the largest proportion of variability in C. pepo is distributed among the accessions. The genetic variability found within accessions can be due to the allogamy, the exchange of landraces seeds between the farmers and also by cultivation of more than one Cucurbita landrace in the same area.