Introgression of new germplasm in current diploid cultivars of garden asparagus from a tetraploid spanish landrace "Morado de Huetor"

Asparagus cultivars have a narrow genetic base. "Morado de Huetor" is a tetraploid landrace with interspecific origin, which could be employed to enlarge the genetic background of diploid cultivars. In order to achieve this goal, diploid commercial cultivars were crossed with triploid plants (4x x 2x) developed in our breeding program. A cross between a diploid plant, found within the tetraploid landrace, and a diploid commercial cultivar was also carried out. All the plants generated were analyzed by flow cytometry to determine the ploidy level selecting those which could be diploids. These plants make up a diploid population referred to in this work as new diploid population. Six expressed sequence tag derived simple sequence repeat (EST-SSR) markers were used to characterize the plants developed and to study their genetic variability. These EST-SSR markers were also employed to characterize diploid commercial cultivars developed in American and European asparagus breeding programs. The results were compared to previous results obtained using "Morado de Huetor". The genetic variability found in the new diploid population was higher than in diploid commercial cultivars. Around 59% of the total alleles observed in the tetraploid landrace "Morado de Huetor" were also detected in the new diploid population. Our results show that the new population has introgressions from "Morado de Huetor" and could be a useful resource for breeding commercial cultivars. (C) 2014 Elsevier B.V. All rights reserved.