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 to adapt to adverse environmental conditions, including heavy metal and metalloid pollution. Uptake and 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 is not related to a reduced uptake, but the null mutation of the aquaporin Nip1.1 gene in Arabidopsis makes the plant completely resistant to the metalloid. This aquaporin, localized in the endoplasmic reticulum, is responsible for arsenite and antimony (Sb) membrane permeation, but the uptake of arsenite occurs also in the null mutant, suggesting a more sophisticated action mechanism than direct uptake. In this study, the DvNip1 gene homologue is cloned and its expression profile in roots and shoots is characterized in different arsenic stress conditions. The use of clonal lines allowed to evidence that DvNip1.1 expression level is influenced by arsenic stress. The proportion of gene expression in roots and shoots can be used to generate an index that appears to be a promising putative selection marker to predict arsenic-resistant lines of Dittrichia viscosa plants.