Simple sequence repeat markers enabled genetic characterization of mulberry germplasm preserved in the CREA's collection of Padua, Italy

Sericulture, silkworm rearing to produce silk, relies primarily on mulberry (Morus sp.pl.) leaves to feed the insect. Today, mulberry is also gaining attention due to the nutritional quality of its fruit, featured with high levels of polyphenols and anthocyanins, especially abundant in the black-fruited varieties. Silk industry was an important economic resource in Italy from Middle Ages to the first half of the 20^th century, and a number of traditional varieties were selected. Although sericulture in Italy has been almost completely abandoned, a remarkable amount of mulberry genetic diversity has been preserved in the CREA's mulberry collection at Padua, Italy. As a complete genetic characterization of this germplasm is still missing, we began to explore the molecular profiles and the genetic relationships of a part of the mulberry collection, using single sequence repeats (SSR) corresponding to 13 previously characterized microsatellite loci. The preliminary results identified different clusters, according to which the Italian germplasm appears to be partially separated from the rest of the accessions, while the presence of some accessions of unknown origin is probably the result of hybridization events. Despite the number of markers used, not all accessions could be differentiated; this result could be attributable to the scarce efficiency of selected SSRs, which were developed on different genetic material. Alternatively, synonyms might be present, i.e. the same genotypes (genetic material) differently identified in the various Italian areas where they were originally cultivated. This study integrates other partial genetic analyses on the Italian mulberry germplasm and could represent a starting point to broaden the study to other collections. Investigating the genetic variability and relatedness among European accessions is relevant for breeding purposes; indeed, the mulberry tree is exploitable both for sericulture and functional food as well as for its rusticity and tolerance to dry and hot Mediterranean climatic conditions; this characteristic suggests its use in areas susceptible to erosion and desertification for environmental purposes.