Desenvolvimento de ferramentas moleculares e seleção assistida por marcadores para resistência ao vírus do mosaico africano na cultura da mandioca

Abstract

This study aimed to develop and characterize TRAP (Target Region Amplification Polymorphism) markers in cassava (Manihot esculenta Crantz) as well as select accessions with genes related to the resistance to Cassava Mosaic Disease (CMD) through marker-assisted selection (MAS). TRAP markers with high polymorphism, low operating cost and easy implementation were developed and validated. From 396 combinations, the 69 most polymorphic were used to characterize 46 germplasm accessions whose polymorphic information content and resolving power values were greater than 0.25 and 3.21, respectively. These TRAPs are associated with genic regions related to starch and carotenoids biosynthesis, cyanogenic compounds, post-harvest physiological deterioration, root formation and defense responses. Regarding the identification of CMD resistance sources, seven accessions which presented alleles linked to CMD2 gene were identified. The discriminant analysis of principal components (DAPC) of the seven CMD resistance sources along with 17 elite cassava varieties indicated the formation of three divergence groups in which the CMD resistance sources were divided into two different groups. The low estimates for genomic relatedness (range -0.167 to 0.681, average 0.076), contributed to the successful orientation of contrasting crosses to generate segregating populations.