J. R. S. Cabral

Assessment of genetic relatedness of the genera Ananas and Pseudananas confirmed by RAPD markers

Genetic relationships among 18 accessions, including 16 of Ananas and two of Pseudananas, were investigated using RAPD molecular markers. The procedure for DNA extraction was adapted from the method of Dellaporta et al. (1983) where an incubation in proteinase K and a purification step were included. From the total of 148 markers scored,132 (89.2%) were polymorphic. The similarity matrix was used for cluster analysis. The phenogram developed from the RAPD bands showed that for most of the cases, the accessions within a species grouped together. Nevertheless, a moderate infraspecific genetic variation was observed. For example, DNA data grouped all A. comosus accessions with a mean similarity coefficient of 0.85. Comparable results were obtained with all other species investigated. The highest genetic divergence was found withinA. lucidus where the mean similarity coefficient among accessions was0.75. A similar level of genetic polymorphism was observed among species,therefore, a definition about which species were involved in the constitution of A. comosus genotypes was not possible. These results agree with the breeders standpoint suggesting that all Ananas species belong to the primary gene pool of pineapple.

Variação de caracteres em híbridos de abacaxizeiro obtidos de diferentes cruzamentos

The inheritance of traits used for the selection of pineapple hybrids is very important for the success of the genetic breeding program of this fruit crop. The objective of the present work was to analyze the variations observed in main traits used for the selection of pineapple hybrids obtained by different crosses. The analysis of variance for 446 evaluated and 213 selected genotypes was carried out for the following traits: plant height from soil to the base of the fruit, peduncle length, weight of the fruit without the crown, weight of the crown, total soluble solids content and titrable acidity. in general, it was observed that fruit weight decreased for the selected hybrids in most crosses and the total soluble solids content increased in all crosses. Positive and significant simple linear correlation was observed between fruit weight and plant height. Also a positive significant simple linear correlation was observed between fruit weight and crown weight, however with lower magnitude, plant height and crown weight, plant height and total soluble solids content, and negative, between total soluble solids content and peduncle length. The difference between the crosses in the selection of pineapple genotypes for the traits studied was verified.