Genetic diversity and phylogenetic analysis in Asian and European Asparagus subgenus species

Abstract

Garden asparagus (Asparagus officinalis L.) is a diploid (2n = 2x = 20), perennial and dioecious species belonging to Asparagus subgenus and worldwide cultivated as a vegetable crop. A narrow genetic base has been pointed out for the current cultivars. Crop wild related species (CWR) could be a valuable genetic resource in this crop but they have been underused up to now. To investigate the phylogenetic relationships between CWR asparagus species from different origin and A. officinalis L., 12 EST-SSR markers were used to assess the genetic variability of 20 accessions. These accessions belong to 10 Asparagus spp. from Asparagus subgenus including wild and naturalized A. officinalis L. (2x, 4x, 8x, 10x) and CWR species with European (A. tenuifolius Lam. (2x), A. pseudoscaber Grec. (6x), A. macrorrhizus Pedrol & al. (12x), A. prostratus Dumort (4x), A. brachyphyllus Turcz. (6x), A. maritimus (L.) Mill. (6x)) and Asian distribution (A. verticillatus L. (2x), A. persicus Baker (2x), A. breslerianus Schult. & Schult. (8x)). A. albus L. (2x) from the Protasparagus subgenus was used as outgroup. As a result, a total of 248 alleles were obtained and specific alleles of accessions were detected among them. After cluster analysis the accessions did not group by their geographical origin. All wild polyploid accessions with European and Asian distributions were grouped together with A. officinalis L. Hence, that cluster could be considered as the ‘officinalis group’ suggesting a monophyletic origin. The diploid accessions of A. verticillatus L. and A. persicus Baker clustered together and were the most genetically distant respect to ‘officinalis group’. The results obtained in this study may provide useful information to design new crosses among accessions aimed to develop new asparagus germplasm or pre-breeding populations.