RESUMO A ampliação da base genética dos materiais de cultivo é trabalho contínuo do programa de melhoramento genético do cupuaçuzeiro (Theobroma grandiflorum). Há necessidade, entretanto, que os parentais envolvidos estejam caracterizados fenotípica e genotipicamente, para auxiliar na escolha dos indivíduos que serão hibridizados, bem como para garantir os mecanismos de rastreabilidade e proteção das cultivares. Este estudo teve como objetivo identificar e selecionar clones de cupuaçuzeiro inter-compatíveis e geneticamente divergentes, utilizando como ferramentas as distâncias genotípica, fenotípica e combinada mistas, assim como as taxas de compatibilidade entre os clones. Estimativas das distâncias genéticas entre os clones foram realizadas com base em 14 iniciadores microssatélites heterólogos de cacaueiro (Theobroma cacao) que amplificam o DNA do cupuaçuzeiro. Para a caracterização fenotípica foram empregadas 14 variáveis relacionadas à produção de frutos. A matriz de dissimilaridade conjunta foi obtida por meio da soma das matrizes de dissimilaridade fenotípica e molecular. A compatibilidade intra e inter-clonal foi estimada através de cruzamentos controlados. Houve uma baixa correlação entre as matrizes de dissimilaridade com base nos dados moleculares e agronômicos. Quanto à compatibilidade, todos os clones foram auto-incompatíveis, contudo, compatíveis entre si, com diferentes taxas. O índice de compatibilidade foi fortemente influenciado pelo grau de relacionamento dos clones. Foi possível identificar e selecionar os conjuntos de clones de cupuaçuzeiro mais promissores para ser usados em melhoramento genético, apesar da ocorrência de relação genética entre eles.

ABSTRACT The expansion of the genetic base of cultivated materials is an ongoing activity of the cupuassu (Theobroma grandiflorum) breeding program. However, the parents involved need to be genotypically and phenotypically characterized to ensure compatibility of crossings, as well as to assist in the selection of more promising individuals for hybridization. This study aimed to identify and select T. grandiflorum clones that are compatible and genetically divergent using tools such as the estimates of genotypic, phenotypic, and combined distances, as well as the compatibility rates among clones. The genetic distance analysis of the clones was performed with 14 heterologous microsatellite primers of cocoa (Theobroma cacao) that amplify the DNA of cupuassu. Phenotypic characterization was based on 14 variables related to fruit production. The joint dissimilarity matrix was obtained by means of the sum of the phenotypic and molecular dissimilarity matrices. The intra- and inter-clonal compatibility was estimated through controlled crossings. A low correlation was noted between the dissimilarity matrices based on the molecular and agronomic data. As for compatibility, all clones were self-incompatible, with different compatibility rates when crossed. The compatibility index was strongly influenced by the degree of relationship of the clones. It was possible to identify and select the most promising sets of cupuassu clones to be used in breeding programs, despite their genetic relationship.

Abstract Genetic variability of a set of 81 accessions of 'sweet' cassavas (Manihot esculenta) collected mostly in the North region of Brazil was investigated with nine microsatellite loci. All loci were polymorphic, with mean of 6.33 alleles per locus. Analyses indicated that 35 multiloci profiles were represented by a single accession, and 46 showed non-unique profiles, represented by eleven genotypes. Forty-six different multiloci profiles were detected. Most of the putative duplicated accessions were collected in different locations. After the removal of putative duplicated genotypes, genetic parameters were estimated and expected heterozygosity was high (HE=0.73), indicating genetic variability. Structure analysis of this set of 'sweet' cassavas divided the 46 genotypes into two clusters (K=2), and a few genotypes had mixed ancestry. Results indicated the habit of exchange of materials among farmers of the North region of Brazil, and the genetic variability to be exploited in genetic breeding efforts.