Application of Elicitors at Two Maturation Stages of Vitis vinifera L. cv Monastrell: Changes in Skin Cell Walls

Abstract

The aim of this study was to evaluate whether the application of two pre-harvest elicitors—methyl-jasmonate (MeJ) and benzothiadiazole (BTH)—to Monastrell grapes, at two maturation stages, affected the composition and structure of the skin cell walls (SCWs) to differing extents. This study was conducted in 2016–2017 on Vitis vinifera L. cv Monastrell. A water suspension of MeJ and BTH, and a mixture of both, was applied at veraison and mid-ripening. The composition of the berry SCW was analyzed. Environmental conditions caused substantial changes in SCW composition, especially at high temperatures. Indeed, a reduction of approximately 50% in the biosynthesis of hemicellulose, proteins and total phenols was observed, accompanied by a slight increase in cellulose and lignin. However, the application of the treatments also caused changes in some SCW constituents: increases in the concentration of phenols, proteins and lignin were observed, especially when the MeJ and MeJ + BTH treatments were applied at veraison. Likewise, a reduction in uronic acids was observed in the MeJ + BTH treatment applied at veraison. These changes in the SCWs could affect their structural characteristics, and therefore influence grape handling in the field and in the winery. Further studies are needed to determine the extent to which MeJ and BTH treatments affect other skin characteristics.

Different response of proanthocyanidins from Vitis vinifera cv. Monastrell depending on time of elicitor application

“…The experiment was conducted in a randomized block design, in which all treatments were applied to three replicates, using ten vines for each replication. The protocol used to apply the different treatments and doses has been described previously 32–34 . Plants (leaves and clusters) were sprayed with a water suspension of the two elicitors: MeJ (Sigma Aldrich, St Louis, MO, USA) at a concentration of 10 mmol L −1 , BTH (Sigma Aldrich) at a concentration of 0.3 mmol L −1 , or a mixture of both (at the mentioned concentrations).…”

“…The protocol used to apply the different treatments and doses has been described previously. [32][33][34] Plants (leaves and clusters) were sprayed with a water suspension of the two elicitors: MeJ (Sigma Aldrich, St Louis, MO, USA) at a concentration of 10 mmol L −1 , BTH (Sigma Aldrich) at a concentration of 0.3 mmol L −1 , or a mixture of both (at the mentioned concentrations). Aqueous solutions (200 mL per plant) were prepared with Tween 80 (Sigma Aldrich) as wetting agent (0.1% v/v).…”

Pre-Harvest Benzothiadiazole Spraying Promotes the Cumulation of Phenolic Compounds in Grapes

“…The formation and buildup of phenolic compounds is a self-defense strategy of grapevine against fungal diseases [ 42 ]. Elicitors can activate metabolic pathways of phenols related to defense mechanisms ( Figure 2 ) [ 22 , 30 , 43 ]. Hence, they are being used as an innovative approach to enhance the phenolic content of grapes as pesticide substitutes to promote plant pathogen resistance [ 60 ].…”

“…The importance of phenolics in plants is beyond question as they help plants defend against biotic and abiotic stresses [ 25 ], enhance the organoleptic and nutritional properties of fruits and corresponding products [ 26 , 27 , 28 ], and have effects on human well-being [ 29 , 30 ]. Grapes are an abundant source of polyphenols [ 27 , 31 , 32 , 33 ], particularly flavanols, flavonols, anthocyanins, proanthocyanidins, hydroxycinnamic acids, and trace amounts of stilbenes [ 34 , 35 , 36 ].…”

“…Regarding the literature on BTH application, several studies in recent decades have applied BTH to grapevines to improve grape quality by altering the phenolic compounds [ 2 , 10 , 23 , 30 , 33 , 43 , 44 , 49 , 50 , 60 , 61 ]. As a result, we summarize the important findings on the impact of BTH on grape phenolic compounds and highlight some unidentified or understudied biological pathways so that subsequent studies may be geared toward them.…”