Identificação, caracterização e validação de marcadores minissatélites para o mamoeiro

Abstract

Identification of polymorphisms in species with low molecular variability, such as papaya (Carica papaya L.) is a challenge for research. The study aimed to identify, characterize and validate the polymorphism of minisatellite markers for the management, conservation and use of papaya’s genetic resources. The genome deposited in database was used to identify minisatellite loci with motifs of 6-500 base pairs (bp). 1730 minisatellites were identified with at least six repetitions (in average 1 out of 156KB), whose average GC content was 28.84% and average of 9.27 repetitions per locus. Motifs with up to 20 bases were the most common (71.5%). Polymorphism of 82 minisatellites was evaluated in 24 papaya accessions and compared with microsatellite markers, whose results demonstrated the presence of 3.10 and 3.57 alleles per locus, respectively. Higher expected heterozygosity (He = 0.52), observed (Ho = 0.16), polymorphic information content (PIC = 0.47) and Shannon-Wiener diversity (H'= 1.10) was observed in the microsatellites comparing with the minisatellite (He = 0.42, Ho = 0.11, PIC = 0.38 and H '= 0.85, respectively), possibly due to the hermaphroditism on most accessions. However, the probability of paternity exclusion and identity was high for both markers. Regarding population structure, both markers indicated the organization of germplasm into two groups (K = 2), although the minisatellites have indicated the presence of a subframe (K = 4). This is one of the first work related to the development of minisatellite for papaya, whose lower polymorphism compared to microsatellite may be offset by its best discriminating power of alleles and greater accuracy in the genotypic identification of individuals.