The use of microsatellite markers for assessing genetic identity of fruit tree crop plant cultivars

Crop plant species are characterized by many cultivars and as defined in Article 2 of the International Code of Nomenclature for Cultivated Plants, (9th 2016 p.190) a “cultivar is an assemblage of plants that has been selected for a particular character or combination of characters, that is distinct, uniform, and stable in those characters, and that when propagated by appropriate means, retains those characters”. Each cultivar needs to satisfy the DUS (Distinctness, Uniformity and Stability) criteria. This is a requirement of determining whether a cultivar differs from existing ones within the same species (the Distinctness part), whether the characteristics used to establish Distinctness are expressed uniformly (the Uniformity part) and that these characteristics do not change over subsequent generations (the Stability part). A DUS test is usually conducted in the field or greenhouse over different successive growing seasons. During this period several mainly morphological characteristics are recorded both on the candidate cultivar and on similar cultivars in what is known as “Common Knowledge”. Differences, if they exist, are established by observation and measurement using internationally agreed protocols. The exclusively use of morphological descriptors could be not an ideal solution since they are influenced by environmental factors. To overcome these limitations, the method of DNA genotyping based on microsatellite markers represents an efficient, reliable, and suitable technique that integrates the information provided by morphological traits. In this study we report the results of the application of these markers to crop plant species like olive, grape, almond, peach and apricot.