Effect of foliar treatment of methyl jasmonate and nanoparticles doped with methyl jasmonate on Monastrell grape skin cell wall

Abstract

The use of elicitors to promote the biosynthesis of secondary metabolites in grapes has been tackled in several reports, however its study linked to nanotechnology is less developed. On the other hand, many works have studied the phenomenon of the extraction in the wine of the compounds that are present in the skin which is affected by several factors as maceration time, temperature, pH, alcoholic degree, use of enzymes. Other important factor to take into account in their extractability of these compounds is the grape cell wall composition, influenced by variety, culture practices, climate conditions, and its facility to be break down. Thus, in this work we present for the first time, the effect  of methyl jasmonate (MeJ) in conventional way and  as nanoparticles doped with MeJ (nano-MeJ) on the cell wall composition of Monastrell and also the relation with its wine phenolic content.Three foliar treatments were applied by triplicate on veraison and a week later, with 10 vines each replicate:  i) Control, ii) MeJ 10 mM  and iii) Nano-MeJ (equivalent to 1mM in MeJ) over three seasons (2019, 2020 and 2021).Cell wall material was isolated using the procedure described by Paladines-Quezada et al. [1]. Uronic acids, proteins, total phenols and cellulosic glucose were analysed following the methodology propose by Apolinar-Valiente et al. [2] .On the other hand the following parameters were evaluated in wine: colour intensity, total polyphenols index and anthocyanins.Regarding cell wall composition, the results showed a decrease in the concentration of cellulosic glucose and total phenols, an increased in proteins and specially in the uronic acids in both treatments applied.With respect to the wine results, the highest anthocyanin concentration was obtained in wines elaborated with MeJ treated grapes but this increase was not evident in wines elaborated with grapes treated with nano-MeJ. So it is possible that the interaction of the increment in proteins and uronic acids and the reduction of cellulosic glucose in the cell wall for this treatment diminished the extractability of phenolic compounds into wine. Other possibility is that the concentration applied in the form of nanoparticles was not sufficient to increase its amount of phenolic compounds in grapes and therefore in wines.Finally, all the parameters studied in grapes and wines were affected by the season studied, being evident the interaction between treatment and year for all of them except for cellulosic glucose and colour intensity. 

References

1. Paladines-Quezada, D.F.; Moreno-Olivares, J.D.; Fernández-Fernández, J.I.; Bautista-Ortín, A.B.; Gil-Muñoz, R. Influence of methyl jasmonate and benzothiadiazole on the composition of grape skin cell walls and wines. Food Chem. 2019, 277, 691–697, doi:10.1016/j.foodchem.2018.11.029.
2. Apolinar-Valiente, R.; Romero-Cascales, I.; Gómez-Plaza, E.; López-Roca, J.M.; Ros-García, J.M. Cell wall compounds of red grapes skins and their grape marcs from three different winemaking techniques. Food Chem. 2015, 187, 89–97, doi:10.1016/j.foodchem.2015.04.042.