Samuel Bello Alonso

Avocado (Persea americana Mill.) is cultivated in a wide range of environments, from tropical and semitropical to subtropical regions. Its fruit, of high nutritional value, is increasingly demanded worldwide. Spain is the main European producer, but avocado cultivation in certain areas, such as the Canary Islands, requires the genetic identification of West-Indian rootstocks because they often show tolerance to low-quality water and soil salinization. In the present study, eight novel Retrotransposon-Based Insertion Polymorphism assays, derived from previously characterized inter-Primer Binding Site markers, have been developed and evaluated by multiplex PCR across 58 P. americana cultivars. The results showed 100% specificity and sensitivity in detecting the West-Indian genomic component, both in pure and hybrid avocado cultivars. This cost-effective and fast molecular tool provides a valuable resource for characterization and selection programs of avocado cultivars genetically related to the West-Indian horticultural race.

Persea americana (avocado) represents one of the most demanded food products worldwide, with an important impact in several agronomy-based economies. The avocado is one of the most salt-sensitive and valuable crops. It is therefore necessary to use salt-tolerant varieties, such as the West Indian, for cultivation in locations with soil salinity problems, such as the Canary Islands. Therefore, characterization of avocado cultivars is in demand, as well as development of molecular tools able to easily identify the main avocado cultivars and horticultural races. In the present work, inter-Primer Binding Site (iPBS) and Inter-Retrotransposon Amplified Polymorphism (IRAP) techniques, which are based on retrotransposon with Long Terminal Repeats (LTR), have been implemented for the first time in P. americana, allowing the characterization of genetic variation among cultivars from the three main horticultural races and the identification of potential P. americana LTR sequences. The iPBS approach showed clear advantages over its technical implementation, and allowed a better delimitation of horticultural races, especially when focused on West Indian cultivars. However, both techniques generated reproducible genetic fingerprints that not only allowed genetic characterization of each cultivar analyzed, but also revealed potential molecular markers for the identification of avocado cultivars and horticultural races.