Copper-based fungicide Bordeaux mixture regulates the expression ofVitis viniferacopper transporters

Abstract

Background and Aims The Bordeaux mixture has been widely used in viticulture, but the response of grape cells (Vitis vinifera L.) to copper is still largely unknown. In the present study, we investigated if copper application in the vineyard could interfere with copper homeostasis through the regulation of the expression of copper transporters (VvCTrs). Methods and Results The VvCTrs characterised in silico are phylogenetically related to COPTs from Arabidopsis and rice. In a field trial, we studied the expression of each VvCTr in grape berries and leaves throughout the season by quantitative real-time polymerase chain reaction. Transcripts of VvCTr1 and VvCTr8 were the most abundant in leaves and berries, respectively, while VvCTrs 4, 5 and 7 were the least expressed, but the application of copper resulted in a significant change in the transcript levels. In plants treated with Bordeaux mixture, the copper concentration increased twofold in the pulp and ninefold on the skin of surface-washed mature berries. Conclusions The expression pattern of VvCTr1-8 depends on the tissue and developmental stage. Four applications of copper following a methodology used in organic farming are sufficient to induce a significant increase in copper content in berry tissues which is either a cause or a consequence of the observed transcriptional reprogramming of the expression of the VvCTrs. Significance of the Study The application of Bordeaux mixture should have major consequences on grapevine copper homeostasis, regulating copper transport at the transcriptional level. A new research avenue emerged towards the characterisation of VvCTr-mediated transport at the molecular level in response to copper.