Abstract

Algarrobo (Prosopis chilensis) is a tree capable of tolerating several biotic and abiotic stresses. Previously, we had evaluated the salinity tolerance of several trees of P. chilensis distributed along Coquimbo, Valparaíso and Metropolitan Regions. What we found were trees, mainly located in the Choapa Valley (Coquimbo Region), which in response to several astringent and very astringent concentrations of NaCl, consistently showed the best performance at germination and physiological levels. In contrast, the poorest response was obtained with trees located in the most North and South limit of its distribution (Elqui Province and Chacabuco Province, respectively). Intrigued by this different geographic response to saline stress, we studied three universal chloroplasts of plants and six nuclear markers specifically designed in P. chilensis. Analysis of chloroplast markers showed that genetic differences at intra and inter population level was observed, and trees coming from north, central and south of distribution were effectively different at chloroplast level. Moreover, nuclear microsatellites confirmed that genetic diversity was also occurring among populations and also confirmed a genetic structure throughout the natural range of this tree. Therefore, molecular marker analysis correlates well with those obtained previously at germination and physiological level, corroborating that higher saline tolerance observed in the trees of Choapa Valley were owing to a genetic diversity. These results generate important information in order to strengthen future works related to breeding programs and conservation initiatives over marginal areas where salinity and other stresses like drought are or might be a constraint