The geminivirus complex known as cassava mosaic disease (CMD) is one of the most devastating viruses for cassava (Manihot esculenta Crantz). The aim of this study was to use molecular-assisted selection (MAS) to identify CMD-resistant accessions and ascertain promising crosses with elite Brazilian varieties. One thousand two hundred twenty-four accessions were genotyped using five molecular markers (NS169, NS158, SSRY028, SSRY040 and RME1) that were associated with resistance to CMD, along with 402 SNPs (single-nucleotide polymorphism). The promising crosses were identified using a discriminant analysis of main component (DAPC), and the matrix of genomic relationship was estimated with SNP markers. The CMD1 gene, previously described in M. glaziovii, was not found in M. esculenta. In contrast, the CMD2 gene was found in 5, 4 and 5 % of cassava accessions, with flanking markers NS169+RME1, NS158+RME1 and SSRY28+RME1, respectively. Only seven accessions presented all markers linked to the CMD resistance. The DAPC of the seven accessions along with 17 elite cassava varieties led to the formation of three divergent clusters. Potential sources of resistance to CMD were divided into two groups, while the elite varieties were distributed into three groups. The low estimates of the genomic relationship (ranging from -0.167 to 0.681 with an average of 0.076) contributed to the success in identifying contrasting genotypes. The use of MAS in countries where CMD is a quarantine disease constitutes a successful strategy not only for identifying the resistant accessions but also for determining the promising crosses.

The aim of this study was to evaluate the selected 41 SSR markers developed for yellow passion fruit (Passiflora edulis f. flavicarpa Sims.) for their transferability to 11 different Passiflora species. Twenty-one SSR were successfully amplified in 10 wild species of passion fruit producing 101 bands. All the markers were amplifiable for at least one species. The mean transferability was 68,8%, ranging from 15,4% (primer PE11) to 100 % (PE13, PE18, PE37, PE41 and PE88). Transferability was higher for the species from the Passiflora subgenus than for those from the Decaloba and Dysosmia subgenus. The results indicated a high level of nucleotide sequence conservation of the primer regions in the species evaluated, and consequently, they could potentially be used for the establishment of molecular strategies for use in passion fruit breeding and genetics.

Objetivou-se avaliar a diversidade genética em germoplasma melhorado (IG) e não melhorado (G-NM) de maracujazeiro amarelo (Passiflora edulis Sims f. flavicarpa Deg), com o uso de marcadores do tipo ISSR (Inter Simple Sequence Repeats). Os genótipos foram agrupados pelo método de neighbor joining e por análise de componentes principais. Foi observado alto número de bandas polimórficas, independente do tipo de genótipo, além de diversos fragmentos específicos dos grupos, de acordo com o nível de melhoramento. Genótipos não melhorados apresentaram maior número de fragmentos polimórficos. O agrupamento hierárquico e de componentes principais foram concordantes na formação de dois grupos bem distintos (IG e G-NM). A análise de variância molecular, utilizada para verificar a diferenciação entre os grupos, evidenciou que 57 e 43% da variação estão entre e dentro dos grupos, respectivamente. Este estudo evidenciou o potencial de uso dos ISSR na determinação do polimorfismo molecular em maracujazeiro amarelo e que o melhoramento tem reduzido a variabilidade genética.

The objective of this study was to evaluate the genetic diversity in improved (IG) and unimproved germplasm (UIG) of yellow passion fruit (Passiflora edulis Sims f. flavicarpa Deg), based on ISSR (Inter Simple Sequence Repeat) markers. The genotypes were grouped by neighbor joining clustering and principal component analysis. Regardless of the genotype, a high number of polymorphic bands was observed, aside from several specific fragments of the groups, according to the level of improvement. Unimproved genotypes had a higher number of polymorphic fragments. The hierarchical and principal component clustering coincided in the formation of two rather distinct groups (IG and UIG). The molecular analysis of variance to check the differentiation between groups showed 57 and 43% of the variation within and between groups, respectively. This study demonstrated the potential of ISSR to determine molecular polymorphism in yellow passion fruit and that breeding has narrowed the genetic variability.