ABSTRACT
The objectives of this study were to identify the genetic variability and estimate the level of homozygosity in a castor bean F4 population using microsatellite markers (SSR). To this end, it was performed the genotyping of the population through 53 pairs of SSR primers. Allele frequencies were estimated by number of alleles per locus, expected heterozygosity (He), observed heterozygosity (Ho) and polymorphic information content (PIC). An array of genetic dissimilarity was generated by Nei and Li index, and hierarchical cluster analysis was performed using the Unweighted Pair-Group Method Averages (UPGMA) method. Polymorphism was detected in a total of eight loci (15.09%) of the 53 evaluated, with the presence of two alleles per locus. Allele frequencies varied between 0.71 and 0.53, and the PIC, between 0.32 and 0.37. The average observed heterozygosity Ho (0.30) was lower than the expected heterozygosity He (0.47). Five dissimilar groups were formed, showing that there is genetic variability among the evaluated genotypes. The highest genetic dissimilarity was 0.708 and the lowest, 0.00. The percentages of homozygous genotypes varied from 25 to 75%. These results show that controlled selfing in castor bean raises the level of homozygosity, important for the breeding program.
Key words
Ricinus communis L.; breeding; selection
