Metabolomic analysis of grapes and leaves from symptomatic and asymptomatic Vitis vinifera grapevines with Esca disease

Abstract

Esca is a grapevine trunk disease spreading in vineyards worldwide, and of rising concern since no efficient treatment is available to mitigate its impact. Trunks, grapes and leaves from symptomatic and asymptomatic Aragonês vines were collected at harvest stage to characterise plant responses associated with this fungal disease. Presence of Esca associated fungi in the trunks was confirmed by molecular methods using ITS region. Metabolomics of grapes and leaves was analysed by Gas chromatography coupled to electron impact ionization time-of-flight mass spectrometry (GC-EI/TOF-MS) and GC coupled to an EI/quadrupole MS (GC-EI/QUAD-MS and showed that both organs from symptomatic plants exhibited a different metabolic reprogramming than those from asymptomatic. Symptomatic leaves present lesser content in tricarboxylic and polyhydroxy acids, and this metabolic adjustment may involve salicylic acid metabolism. On the other hand, symptomatic fruits accumulate long-chain fatty acids probably related with cuticle reinforcement to mitigate changes in water transport caused by trunk damage, and defence-related metabolites such as α-tocopherol. Symptomatic berries also presented alterations in volatile aroma compounds such as C6-volatiles, and acetic acid suggesting an impact on subsequent wine quality. Altogether this study, identified putative metabolic markers associated with Esca disease in plants with different symptomatology and contributed to a physiological understanding of this fungal disease that could help in the development of mitigation strategies for its spread.