Developmental pattern of grapevine (Vitis vinifera L.) berry cuticular wax: Differentiation between epicuticular crystals and underlying wax

Abstract

The grapevine berry surface is covered by a cuticle consisting of cutin and various lipophilic wax compounds. The latter build the main barrier for transpirational water loss and protect the fruit against environmental factors e.g. pests, mechanical impacts or radiation. The integrety of the fruit surface is one important key factor for post-harvest quality and storage of fruits. Nonetheless, the developmental pattern of cuticular wax was so far only investigated for a very limited number of fruits. Therefore, we performed comparative investigations on the compositional and morphological nature of epicuticular wax crystals and underlying wax during fruit development in Vitis vinifera. The main compound oleanolic acid belongs to the pentacyclic triterpenoids, which occur very early in the development in high amounts inside the cuticle. The amount increases until veraison and decreases further during ripening. In general, very-long chain aliphatic (VLCA) compounds are present in much smaller amounts and alcohols and aldehydes follow the same trend during development. In contrast, the amount of fatty acids constantly increases from fruit set to ripening while wax esters only occur in significant amount at veraison and increase further. Wax crystals at the fruit surface are solely composed of VLCAs and the morphology changes during development according to the compositional changes of the VLCA wax compounds. The remarkable compositional differences between epicuticular wax crystals and the underlying wax are important to understand in terms of studying grape-pest interactions or the influence of environmental factors, since only wax crystals directly face the environment.

Evaluation of Wild, Wine, Table, and Raisin Grapevine (Vitis spp.) Genotypes in Gedeo Zone, Southern Ethiopia

“…The raisin and table grapevines had higher fruit number compared to the wild grapevine cultivars but lower than the wine grapevine cultivars ( Figure 7 ). This is in accordance with [ 21 , 26 ] that reported that wild grapevine cultivars had lower number of fruits per plant, smaller berry size, and weak berry development patterns compared to the modern wine, table, and raisin grape cultivars. This might be due to genetic variations [ 15 ], poor canopy management, and vigorous nature of wild grapevine species [ 13 , 14 ].…”

Physical and Chemical Traits of Grape Varieties Influence Drosophila suzukii Preferences and Performance

“…We assume that the removal of epicuticular waxes in "Regent", "Acolon", "Pinot Noir", and "Pinot Blanc" may have resulted in a less slippery surface and better grip for D. suzukii tarsae, whereas this does not seem to be the case in "Müller-Thurgau" (Figures 2D,I). Wax crystals of "Müller-Thurgau" are quite fine, rather filamentous and relatively flat, as also recently shown by Arand et al (2021).…”

“…Overall, more flies rested and deposited more eggs on berries, whose epicuticular wax layers were removed (dewaxed), compared to intact berries except of "Müller-Thurgau" (Figures 2D,I). When berries start to touch each other during development, their wax coat appears patchier and glossy spots become visible (Arand et al, 2021). Thus, parts of epicuticular wax crystals may also be reduced under natural conditions, causing potentially higher acceptance by this fly species.…”

“…Differences in cuticular wax composition among varieties have been found in various crop plants (Leide et al, 2007;Rebora et al, 2020), including V. vinifera (Radler, 1965;Pensec et al, 2014). In this species, a high heterogeneity in the fruit cuticle wax was shown, where epicuticular wax crystals solely consist of very-long-chain aliphatic compounds, while the intracuticular wax is dominated by triterpenoids (Arand et al, 2021).…”

Comparative Analysis of Cuticular Wax in Various Grape Cultivars During Berry Development and After Storage

“…The composition and crystal morphologies of cuticular wax were influenced by a variety of factors including development stages, species, tissues, and environmental conditions ( 2 , 4 , 17 ). Previous studies have determined the wax composition in the berries of grape cultivars and identified several related genes, including CER and WIN1, in grape genome ( 3 , 5 , 18 ). However, our knowledge on the accumulation characteristics and molecular mechanisms of cuticular wax in grape is still fairly restricted.…”