Zinc supply impacts on the relative expression of a metallothionein-like gene in Coffea arabica plants

Abstract

Background and aims Zinc (Zn) is an essential nutrient for plants, as it functions as a component and cofactor of enzymes. Metallothioneins (MTs), are known to participate in the process of metal homeostasis have been hypothesized to be partially responsible for the distribution of Zn in plants. We aimed to characterize putative MT-like genes and to analyze their expression in response to Zn supplementation in coffee. Methods Coffee seedlings were cultivated in Hoagland’s solution without Zn, and after 120 days, Zn was supplied at different concentrations. Fully expanded leaves were collected for analysis of MT relative gene expression, Zn concentrations and enzymatic activity. Results Seven putative genes were obtained in a search of the CAFEST database. Electronic Northern analysis revealed that MTs were expressed in different tissues, developmental stages and mostly under arachidonic acid treatment. Superoxide dismutase (SOD) quantification indicated that the Zn dose influenced the enzymatic activity; the lowest being at 0.6 % Zn. Quantitative expression analyses of putative MTs demonstrated that these genes are differentially expressed in response to Zn supplementation. Conclusions There is a positive correlation between MT relative expression and Zn concentration and we believe that MTs play an important role in Zn homeostasis in coffee.