Exploring the variability of cuticular compounds in different grapevine cultivars
Résumé
Plant cuticle is the first shield which protects aerial epidermis against environment constraints, notably by limiting water loss, UV irradiation damage, pest infestation and pathogen infection. This lipophilic barrier is subdivided in two parts: (i) an external wax layer constituted of very-long-chain fatty acids, primary alcohols, alkanes, aldehydes or triterpenoids, and (ii) a deeper cutin polymer made of hydroxy-/epoxy- fatty acid monomers, which is to a certain extent integrated to cell wall [1]. Cuticle compounds identification and quantification are well established in different species such as grapevine [2], but rarely over a wide range of cultivars [3]. By targeting a single organ maturity, we provide the first leaf and berry cuticle composition comparison study which integrates about fifty grape varieties from the same vineyard. GC-MS coupled with GC-FID analyses indicate that leaf waxes are mostly composed of primary alcohols 1-hexacosanol or 1-octacosanol while berry waxes are dominated by triterpenoids oleanic and ursolic acid. Classically, cutin of both organs contains predominantly palmitic acid hydroxylated and ω-OH-fatty acids stearic and oleic acid hydroxylated or epoxylated. Despite the similar pattern structuring each organ cuticle, wax and cutin compounds were differentially accumulated according to cultivars. This study supplies an overview of cuticle diversity within the same species taking grapevine as model. Cuticle relationship with agronomic traits observed during the sampling year will be highlighted as well as variety tolerance against abiotic and biotic stress. [1] Fernández V, Guzmán-Delgado P, Graça J, Santos S, Gil L (2016) Cuticle structure in relation to chemical composition: re-assessing the prevailing model. Frontiers in Plant Science 7: 427 [2] Lara I, Belge B, Goulao LF (2015). A focus on the biosynthesis and composition of cuticle in fruits. Journal of agricultural and food chemistry. 63:4005-4019 [3] Radler F (1965) The main constituents of the surface waxes of varieties and species of the genus Vitis. American Journal of Enology and Viticulture 16: 159-167
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