Genetic diversity assessment of the almond (Prunus dulcis (Mill.) DA Webb) traditional germplasm of Algarve, Portugal, using molecular markers

In this study, 123 almond (Prunus dulcis (Mill.) D. A. Webb) trees identified among traditional orchards in the Algarve region and 53 trees of the local field collection managed by the regional office of the Portuguese Ministry of Agriculture (DRAALG) were assessed using isozyme, inter- single sequence repeat and simple sequence repeat or microsatellite techniques for the evaluation of genetic diversity and genetic relatedness and identification of new accessions for the field collection. The isozyme analysis allowed the distribution of the 176 plants into 13 different classes of enzyme similarity, while the use of DNA markers increased the distribution of the analysed trees among 140 discriminating DNA patterns. Multiple cases of homonymy and synonymy were identified in the local germplasm. Some traditional varieties, such as Lourencinha, appeared to be relatively homogeneous, while other local denominations, e.g. Galamba, included diverse genotypes. Of the 13 commercial varieties analysed in this study, 11 assembled in one major cluster clearly differentiated from the majority of the local genotypes. These results reinforced the perception that the Algarve traditional germplasm constitutes an important repository of genetic diversity, eventually carrying alleles of high agricultural interest such as the recently identified Phomopsis resistance in the traditional variety Barrinho Grado.