LAUSR

Universidade Federal do Recôncavo da Bahia, Centro de Ciências Agrárias, Ambientais e Biológicas, Cruz das Almas, Bahia, Brazil Embrapa Mandioca e Fruticultura, Núcleo de Recursos Genéticos e Desenvolvimento de Variedades, Cruz das Almas, Bahia, Brazil Correspondence Eder Jorge de Oliveira, Embrapa Mandioca e Fruticultura, Rua da Embrapa, Caixa Postal 007, Cruz das Almas, Bahia 44380-000 , Brazil. Email: [email protected] Funding information Conselho Nacional de Desenvolvimento Científico e Tecnológico; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior; Fundação de Amparo à Pesquisa do Estado da Bahia; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB) Cassava (Manihot esculenta Crantz) is a species whose natural diversity has great food, industrial and energy potential. This study aimed to evaluate the genetic diversity, and population structure of 1,580 accessions belonging to the international germplasm conserved in Brazil using 20,601 single-nucleotide polymorphism markers. The average values of polymorphic information content (PIC), inbreeding (f ), observed heterozygosity (Ho) and expected heterozygosity (He) were 0.24, 0.21, 0.23 and 0.30, respectively, presenting levels of genetic diversity compatible with the nature of the marker (predominantly biallelic) and with the species reproductive system. The mean values of He, Ho, PIC and f were similar for the 18 chromosomes of the species. At the individual level, f values ranged from 0.49 to 0.97, with an average of 0.69, whereas some cassava accessions showed f > 0.90. The values of linkage disequilibrium ranged from 15 to 20 kb (r = 0.20). In the discriminant analysis of principal components (DAPC), 22 groups were formed with probabilities of assignment of individuals above 0.99. No association was observed between DAPC grouping and clusters based on phenotypic data (cyanogenic compound content and colour of the root pulp) and on genetic and geographic origin. However, the DAPC grouping resulted in greater variation between groups (14.85%). This information suggests extensive exchange of cassava germplasm in Brazil and wide molecular and phenotypic diversity. These results will provide a better understanding of the preserved genetic variability and the population organisation of the germplasm.