The grapevine metabolite profile of phloem sap is modified by flavescence dorée

Abstract

Flavescence dorée (FD) has been recorded in French vineyards since the mid-1950s; it has rapidly become a major threat to vineyard survival in different European grape-growing areas. Infection by the phytoplasma ‘Candidatus Phytoplasma vitis’ causes leaf chlorosis and disturbs primary and secondary core metabolic pathways; it can also occlude sieve plates, therefore affecting normal solute transport through the phloem. Thus, in the present study we hypothesised that the metabolomic fingerprint of the phloem sap changes in FDp-infected vines. The metabolome of the phloem sap collected by centrifugation from the bark of the stem of healthy and infected vines (cv. ‘Loureiro’) was profiled by ESI-HRMS at two snapshot time points: E-L 33 (grape berry still hard and green) and E-L 38 (grape berry at maturity). An untargeted analysis of the phloem sap enabled the identification of 476 metabolites, whereas the targeted analysis focused on eight main classes, namely acids, sugar and polyols, amino acids, phenolic acids, hormones, vitamins and N compounds, as well as on several minor classes like fatty acids, phenols or diols. Depending on the developmental stage of the vine, major differences were observed in the composition of cv. ‘Loureiro’ phloem sap in response to FD infection in terms of sugar, organic acid and amino acid content; furthermore, compounds involved in plant defense, such as salicylic acid, ABA, vitamin C and gallic acid also significantly changed. Overall, these results have contributed towards increasing knowledge about the complex interactions between vine and FD phytoplasma.

Plant Heterotrophic Cultures: No Food, No Growth

“…Raffinose-like sugars are considered as an important transport form of carbon for some plants, in particular from the families Cucurbitaceae and Scrophulariaceae [ 88 , 113 ]. A study of the composition of phloem sap showed the presence of oligosaccharides, but in smaller quantities than sucrose [ 110 , 114 , 115 , 116 ]. The role of raffinose in the redistribution of carbon in the plant has been confirmed by methods of genetic engineering [ 110 ].…”

“…They can also play the role of reserves [ 121 ] and contribute to stress resistance [ 122 ]. A significant number of these were found in phloem exudates [ 114 , 115 , 116 , 123 , 124 ]. However, cell lines of only a few species are capable of utilizing sugar alcohols for growth supply.…”

“…Sugar alcohols enter the metabolism through their conversion by dehydrogenases and oxidoreductases into hexoses [ 82 , 120 , 128 ]. Inositol, which is cyclic polyol, has been detected in the phloem of many plants [ 82 , 114 , 116 ]. It plays an important role in many processes [ 129 ].…”

“…The metabolic analysis of various plant organs and tissues, as well as phloem sap [ 114 , 115 , 116 , 123 , 124 ], detected wide spectra of sugars and their derivatives. The intensive sugar metabolism in plant cells is a basis for groups of monosaccharides in maintaining cell growth.…”

A metabolome and transcriptome survey to tap the dynamics of fruit prolonged shelf-life and improved quality within Greek tomato germplasm

“…Non-polar (NP) and semi polar (SP) metabolites were extracted from, respectively, 3 and 10 mg of freeze-dried tomatoes, harvested at the red stage, for a total of three replicates for each of the seven SSL and the seven LSL genotypes. Liquid chromatography coupled to high-resolution mass spectrometry (HPLC-APCI/ESI-HRMS) conditions were as previously reported for NP (Teixeira et al, 2023) and SP (Dono et al, 2022) metabolome, respectively. Metabolites were identified through the comparison with authentic standards or MS/MS spectra when available and on the basis of the accurate masses obtained from the Pubchem database (http://pubchem.ncbi.nlm.nih.gov/) for native compounds or from the Metabolomics Fiehn Lab Mass Spectrometry Adduct Calculator (http://fiehnlab.ucdavis.edu/staff/kind/Metabolomics/MS-Adduct-Calculator/) for adducts.…”