Evaluation of Dittrichia viscosa Aquaporin Nip1.1 Gene as Marker for Arsenic-Tolerant Plant Selection

Dittrichia viscosa (L.) Greuter is gaining attention for its high genetic plasticity and ability toadapt to adverse environmental conditions, including heavy metal and metalloid pollution. Uptakeand translocation of cadmium, copper, iron, nickel, lead, and zinc to the shoots have been characterized, but its performance with arsenic is less known and sometimes contradictory. Tolerance to As isnot related to a reduced uptake, but the null mutation of the aquaporin Nip1.1 gene in Arabidopsismakes the plant completely resistant to the metalloid. This aquaporin, localized in the endoplasmicreticulum, is responsible for arsenite and antimony (Sb) membrane permeation, but the uptake ofarsenite occurs also in the null mutant, suggesting a more sophisticated action mechanism thandirect uptake. In this study, the DvNip1 gene homologue is cloned and its expression profile in rootsand shoots is characterized in different arsenic stress conditions. The use of clonal lines allowedto evidence that DvNip1.1 expression level is influenced by arsenic stress. The proportion of geneexpression in roots and shoots can be used to generate an index that appears to be a promisingputative selection marker to predict arsenic-resistant lines of Dittrichia viscosa plants.