Urease and N recycling in plants, and the role of Ni as an essential micronutrient

Abstract

The fact that Ni is part of the active site of urease in plants, and this enzyme is responsible for the elimination of toxic levels of urea in plants has been the justification for classifying this element as essential. In contrast, urease activity has been almost strictly related to the urea produced in the conversion of arginine to ornithine and especially in seeds. In vegetative tissues, leaves, for example, the levels of urease activity is very low. Thus, there are few studies that actually show that Ni is essential in plants, being restricted mainly to soybean, and even fewer studies that highlight the role of urease in plant metabolism. Recent studies have shown that urease, and consequently Ni, may play a role in the recycling of N between metabolic pools in plants under stress. This project seeks to evaluate this hypothesis by studying the levels of N metabolites related with urea and the expression of genes related to metabolic enzymes acting on these pools in Arabidopsis thaliana plants subjected to Ni nutrition and stress.