Influence of Benzothiadiazole on the Amino Acids and Aroma Compositions of ‘Cabernet Gernischt’ Grapes (Vitis vinifera L.)

Abstract

The application of elicitors enhances grape quality, especially the volatile compounds. There are few studies on the influence of elicitors on the aroma compositions of grapes. Additionally, studies on the amino acids and aroma profiles of ‘Cabernet Gernischt’ grapes are scant. The objective of this work was to evaluate the effect of benzothiadiazole (BTH) treatments on the amino acids and aroma profiles of ‘Cabernet Gernischt’ grapes during berry development. BTH was sprayed on berries at three different stages during grape development; the fruit set period, swelling, and veraison stages. Physicochemical parameters, amino acids, and aroma compounds of the grapes were evaluated. The results showed increased an weight and color quality of treated grapes, while the content of primary metabolites such as sugar and amino acids in treated grapes declined relative to control grapes. However, total concentrations of the various aroma classes were higher in treated grapes, except for carbonyls and terpenoids, which presented higher levels in control grapes than in BTH-treated grapes. The correlation analysis between amino acids and aroma compounds revealed positive correlations in both samples with few negative correlations in BTH samples. The odor activity values (OAVs) affirmed the floral, fruity, and fresh-green nature of ‘Cabernet Gernischt’ grapes. BTH application to ‘Cabernet Gernischt’ berries significantly influenced the compositional qualities of the grapes.

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

“…The grapevine uses multiple signaling pathways to synthesize defensive compounds based on the kind of attack or stress [ 81 ]. One of the resistance processes is known as SAR, which depends on the activation of secondary metabolic pathways and the synthesis of secondary metabolites, including phenolic compounds, in response to an attack or stress on the vine [ 10 , 16 , 42 , 60 ].…”

“…Some practices can directly influence the secondary metabolism of the berries. However, in some cases, primary metabolism is affected first, which may indirectly affect secondary metabolism [ 16 ].…”

“…Prevalent diseases such as gray mold ( Botrytis cinerea ), powdery mildew ( Erysiphe necator ), and downy mildew ( Plasmopara viticola ) impair the healthy development of grapevines and the quality of their berries [ 16 , 17 ]. Chemical pesticides are the most effective and common method of preventing or combating such diseases, but they or their degradation products negatively affect human health and the environment [ 16 , 18 ]. At present, green and climate-friendly production strongly calls for innovative and friendly disease control measures to ensure healthy and high-quality grape production.…”

“…Among elicitors, benzothiadiazole (ASM or BTH, Bion) ( Figure 1 ) has attracted much interest from researchers to improve plants’ resistance to pathogens and enhance the phenolic compounds of grapes [ 23 , 33 , 49 ]. BTH is an efficient systemic acquired resistance (SAR) booster that has anti-microbial properties and intensifies resistance in the plant by inducing pathogenesis-related protein genes (PR), which activates SAR signal transduction routes, resulting in SAR formation [ 10 , 16 , 18 , 49 , 50 ]. Additionally, BTH treatment can promote the buildup of antifungal compounds such as phenols [ 22 , 51 ] and can be rapidly degraded in plant tissues without producing residues [ 52 ].…”

“…Furthermore, BTH has been found to trigger key enzymes of the secondary metabolism pathway in fruits [ 10 , 52 , 54 , 55 , 56 ]. At the same time, it also activates metabolic pathways [ 20 ], causing the biosynthesis of bioactive secondary metabolites [ 23 , 44 ], including phenols and aromatic compounds ( Figure 2 ) [ 16 , 33 , 49 , 52 ]. The only side effect of elicitor application is fitness costs which occur preferentially in certain crops but not all, depending on the plant system [ 57 , 58 ].…”