The aim of this work was to evaluate the carotenoid content and genetic variability of banana accessions from the Musa germplasm collection held at Embrapa Cassava and Tropical Fruits, Brazil. Forty-two samples were analyzed, including 21 diploids, 19 triploids and two tetraploids. The carotenoid content was analyzed spectrophotometrically and genetic variability was estimated using 653 DArT markers. The average carotenoid content was 4.73 µg.g-1, and ranged from 1.06 µg.g-1 for the triploid Nanica (Cavendish group) to 19.24 µg.g-1 for the triploid Saney. The diploids Modok Gier and NBA-14 and the triploid Saney had a carotenoid content that was, respectively, 7-fold, 6-fold and 9-fold greater than that of cultivars from the Cavendish group (2.19 µg.g-1). The mean similarity among the 42 accessions was 0.63 (range: 0.24 to 1.00). DArT analysis revealed extensive genetic variability in accessions from the Embrapa Musa germplasm bank.

Dois isolados do vírus Y da batata (Potato virus Y, PVY) foram caracterizados biologicamente como pertencentes às estirpes necrótica (PVY-NBR ) e comum (PVY-OBR) com base nos sintomas induzidos em plantas-teste. Caracterização adicional foi realizada com a determinação da seqüência de nucleotídeos do cDNA correspondente à extremidade 3' do genoma viral. A seqüência obtida continha 195 nucleotídeos (nt) que codificam uma parte do gene da inclusão nuclear b (NIb), 804 nt da capa proteíca (CP) e 328 nt em PVY-OBR e 326 nt em PVY-NBR da região 3' não traduzida (UTR). A análise da seqüência mostrou ser composta por uma única fase aberta de leitura contendo parte do NIb e a CP consistindo de 267 aminoácidos. Os dois isolados apresentaram uma similaridade de 95,1% na seqüência de aminoácidos da CP. A CP e a seqüência 3'-UTR dos isolados brasileiros foram comparados com as seqüências de outros isolados de PVY previamente relatados e árvores filogenéticas foram construídas. As árvores mostraram a delimitação de dois grupos distintos, um contendo a maioria das estirpes comuns e o outro com as estirpes necróticas. PVY-OBR foi agrupado no grupo comum e PVY-NBR no necrótico.

Two Brazilian Potato virus Y (PVY) isolates were biologically characterized as necrotic (PVY-NBR) and common (PVY-OBR) based upon symptoms on test plants. Additional characterization was performed by sequencing a cDNA corresponding to the 3' terminal region of the viral genome. The sequence consisted of 195 nucleotides (nt) coding part of the nuclear inclusion body b (NIb) gene, 804 nt of the coat protein (CP) gene, and 328 nt (PVY-OBR) or 326 nt (PVY-NBR) of the 3'-untranslated region (UTR). Translation of the sequence resulted in one single open reading frame with part of the NIb and a CP of 267 amino acids. The two isolates shared 95.1% similarity in the CP amino acid sequence. The CP and the 3'-UTR sequence of the Brazilian isolates were compared to those of other PVY isolates previously reported and unrooted phylogenetic trees were constructed. The trees revealed a separation of two distinct clusters, one comprising most of the common strains and the other comprising the necrotic strains. PVY-OBR was clustered in the common group and PVY-NBR in the necrotic one.