Germplasm resource evaluation and the underlying regulatory mechanisms of the differential copper stress tolerance among Vitis species.

The inappropriate application of copper (Cu)-based fungicides causes toxicity in the vineyard. However, limited data are available about which are the tolerant grapes cultivars and underlying physiological and molecular mechanisms against Cu stress. Therefore, we evaluated the damage status of 302 perennial Vitis germplasm resources by spraying their leaves with a 10 mM Cu (excessive Cu) solution for 48 h. Then, we studied the effects of Cu-induced toxicity in two Vitis vinifera × Vitis labruscana (V. vinifera × V. labruscana) cultivars, i.e., 'Takasumi' ('Ta') and 'Moldova'('Mo') with significantly different Cu tolerance levels by analyzing their gene expression, metabolites, and other physiological parameters. V. vinifera × V. labruscana showed a higher Cu tolerance than Vitis vinifera (V. vinifera), with 'Ta' being more tolerant than 'Mo'. Herein, we detected 2,083 up-regulated and 4,474 down-regulated differentially expressed genes (DEGs), and 87 up-regulated and 84 down-regulated differentially accumulated metabolites (DAMs) in Ta vs. Mo. As compared to the Cu-sensitive cultivars, the Cu-tolerant cultivars displayed some Cu and reactive oxygen species (ROS) detoxification measures, including (a) inhibiting Cu uptake and enhancing its transportation, sequestration, and efflux; (b) ROS scavenging by upregulating antioxidant-related genes, like CAT8 , SOD1 , and TRX2 , and increasing the accumulation of ascorbate-glutathione (AsA-GSH) cycle metabolites (ascorbic acid and oxidized L -glutathione); (c) inducing autophagy-related genes expression and secondary metabolism due to elevated intermediary metabolites, including those of tricarboxylic acid (TCA) cycle (DL-malic acid, citric acid, and fumaric acid) and flavonoid pathway (catechin, procyanidin B1, and theaflavin); (d) increasing the content of phytohormones, like abscisic acid (ABA), brassinosteroids (BRs), and salicylic acid (SA). Therefore, our findings will not only support future functional analysis but also decipher the possible Cu-induced stress response mechanisms underlying the cultivar-level differences in Cu accumulation. [Display omitted] • V. vinifera × V. labruscana showed higher Cu tolerance levels than V. vinifera. • Inhibiting Cu uptake and enhancing Cu transportation might improve tolerance of Vitis. • Activating antioxidative mechanisms might enhance Cu tolerance of Vitis. [ABSTRACT FROM AUTHOR]