Root temperature regulated frost damage in leaves of the grapevine Vitis vinifera L

Background and Aims Soil temperature is an important factor that regulates the response of shoots to extreme temperature conditions, such as heat stress. Little information is known, however, about the role that soil temperature plays in regulating the response of grapevine leaves to frost. The aim of this work was to explore the effect of soil temperature on the frost resistance of leaves and to comprehensively reveal the potential physiological mechanism. Methods and Results In a pot experiment the roots of grapevine seedlings (Vitis vinifera L. cv. Merlot) were kept warm (WARR, 20°C) or cold (COLR, 0°C) when the leaves were subjected to frost treatment. After frost, the degree of injury to the leaves was recorded, and a frost index was calculated. A non‐targeted metabolomics analysis based on GC‐time of flight/MS of the leaves of WARR and COLR after frost treatment revealed metabolic differences induced by variable root temperature. Severe damage was found in COLR leaves; in contrast, slight frost injury occurred in WARR leaves. Frost treatment at a root zone temperature of 0 and 20°C triggered significant changes in metabolites and metabolic pathways in the leaves of grapevine compared with those of the Control, with more metabolites and metabolic pathways altered in the leaves of WARR than in those of COLR. The relevant pathways in the leaves of WARR and COLR that were significant compared with those of the Control were the citrate cycle (TCA cycle) as well as glycine, serine and threonine metabolism, which are related to carbohydrate metabolism and amino acid metabolism, respectively. Conclusions Soil temperature affected the frost tolerance of the leaves of grapevine. Different metabolic mechanisms in the leaves of grapevine responded to freezing temperature, regulated by the different root zone temperature. Significance of the Study The role that the root zone temperature plays in frost damage in leaves provided an integrative insight to investigate the frost mechanism.