AFLP evaluation of genetic similarity among laurel populations (Laurus L.)

Abstract

Two species have traditionally been considered within the genus Laurus: L. nobilis L. and L. azorica (Seub.) Franco. The first is characterized by the presence of glabrous twig leaves and is located in the Mediterranean region. It can be found as cultivated or naturalized, and has been reported in Spain, France, Italy and Greece. L. azorica is characterized by the presence of densely tomentose to hirsute twig leaves and has been described in the Azores, Madeira and the Canary Islands. We have found that some natural populations of Laurus in Northern Spain, which are considered to belong to L. nobilis, have hirsute young buds, with wide variation in hair number and density, in contradiction with taxonomical descriptions reported for this species. In order to evaluate the genetic similarity between these Laurus populations and the two reported species, we have analyzed 14 populations of L. nobilis and L. azorica from different geographical areas, including the Iberian peninsula, the Canary and Madeira Islands, France and Italy, using amplified fragment length polymorphisms (AFLPs). UPGMA clustering and principal component analysis (PCA) of the AFLP data revealed a low genetic similarity between the Iberian populations, including populations from Northern Spain, and the rest of the populations analyzed from France and Italy. Moreover, laurel accessions from the Iberian peninsula showed higher genetic similarity to those from the Canary Islands and Madeira, originally identified as L. azorica, than to samples from populations along the Mediterranean area, morphologically classified as L. nobilis.