## 3 Elicitors and Their Classifications
### Chitosan (CHT)
Chitosan can be applied directly to plants in a liquid state or the soil in powdery or liquid  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Elicitor** & **Grape** & **Impact on Quality** & **Reference** \\ \hline \multirow{4}{*}{Methyl Jasmonate (MeJ)} & \multirow{4}{*}{Hamburg Muscat (Black Muscat)} & MeJ activated terpenoid biosynthesis pathway; increased concentrations of free and glycosylated monoterpenes in grapes and wine; improved aroma quality & [117] \\ \cline{1-1} \cline{2-3} Nano-Methyl Jasmonate (nano-MeJ) & Monastrell & Significant increase of beneficial stilbenes (_trans_-resveratrol, _cis_- and _trans_-piceid) & [96] \\ \hline \multirow{4}{*}{Ozonated water} & \multirow{4}{*}{Bobal} & Improved chromatic characteristics; favored the accumulation of phenolic compounds; increased some free volatile aromas; generally improved grape quality & [97] \\ \cline{1-1} \cline{2-3}  & & MeJ improved the synthesis of p-cymene, methyl jasmonate, and hexanal (1 st vintage) while diminishing the content of some C\({}_{6}\) alcohols, esters, several terpenes, and \(\beta\)-damascenone in the 2 nd vintage; several positive aroma contributors were improved in the 3 rd vintage & [118] \\ \hline \multirow{4}{*}{Methyl Jasmonate (MeJ), chitosan (CHT), and yeast extract (YE)} & \multirow{4}{*}{Tempranillo} & CHT and YE decreased the concentrations of several amino acids while MeJ increased the concentrations of most amino acids especially Met and Phe; All treatments decreased the synthesis of grape volatile compounds & [35, 67, 119] \\ \hline \multirow{4}{*}{Methyl Jasmonate (MeJ)} & \multirow{4}{*}{Sangiovese} & Delayed maturity, increased concentrations of several grape aroma classes, a rise in wine aroma concentrations with improved sensorial characteristics & [61] \\ \hline \multirow{4}{*}{Methyl Jasmonate (MeJ) and Phenylalanine (Phe)} & \multirow{4}{*}{Grenache} & Both elicitors enhanced the volatile content of grenache grapes; MeJ improved terpenoids and C\({}_{13}\) norisoprenoids; most of the positive compounds were enhanced by Phe treated; Phe + MeJ increased concentrations of most volatiles & [120] \\ \cline{1-1} \cline{2-3}  & & MeJ increased the concentrations of & \\ \cline{1-1} \cline{2-3}  & & MeJ increased the concentrations of & \\ \cline{1-1} \cline{2-3}  & & MeJ activated terpenoid biosynthesis & \\ \cline{1-1} \cline{2-3} Methyl Jasmonate (MeJ) and Phenylalanine (Phe) & Graciano and Temptranillo & decreased the content of some amino acids in Temptranillo but did not affect the total amino acids content & [121] \\ \hline \multirow{4}{*}{Benzothiadiazole (BTH) and MeJ} & \multirow{4}{*}{Monastrell} & No effect on alcohols and esters; increased concentrations of terpenes; synthesis of some terpenes only in treated wines; improved sensory qualities; increased levels of phenolic compounds & [122, 123, 124, 125] \\ \cline{1-1} \cline{2-3}  & & CHT improved the volatile profile, flavor, and taste of Groppello wine, increased total acetals, and alcohols; BTH increased total acetals and esters & [126] \\ \cline{1-1} \cline{2-3}  & & CHT improved the volatile profile, flavor, and taste of Groppello wine, increased total acetals, and alcohols; BTH increased total acetals and esters & [126] \\ \cline{1-1} \cline{2-3}  & & CHT improved the synthesis of p-cymene, methyl jasmonate, and hexanal (1 st vintage) while diminishing the content of some C\({}_{6}\) alcohols, esters, several terpenes, and \(\beta\)-damascenone in the 2 nd vintage; several positive aroma contributors were improved in the 3 rd vintage & [118] \\ \cline{1-1} \cline{2-3}  & & CHT and YE decreased the concentrations of several amino acids while MeJ increased the concentrations of most amino acids especially Met and Phe; All treatments decreased the synthesis of grape volatile compounds & [35, 67, 119] \\ \hline \multirow{4}{*}{Methyl Jasmonate (MeJ)} & \multirow{4}{*}{Sangiovese} & Delayed maturity, increased concentrations of several grape aroma classes, a rise in wine aroma concentrations with improved sensorial characteristics & [61] \\ \cline{1-1} \cline{2-3}  & & Both elicitors enhanced the volatile content of grenache grapes; MeJ improved terpenoids and C\({}_{13}\) norisoprenoids; most of the positive compounds were enhanced by Phe treated; Phe + MeJ increased concentrations of most volatiles & [120] \\ \cline{1-1} \cline{2-3}  & & MeJ increased the concentrations of & \\ \cline{1-1} \cline{2-3}  & & MeJ increased the concentrations of & \\ \cline{1-1} \cline{2-3}  & & MeJ increased the concentrations of & \\ \cline{1-1} \cline{2-3}  & & several amino acids in Graciano; & \\ \cline{1-1} \cline{2-3}  & & decreased the content of some amino acids in Temptranillo but did not affect the total amino acids content & [121] \\ \cline{1-1} \cline{2-3}  & & No effect on alcohols and esters; & \\ \cline{1-1} \cline{2-3}  & & Increased concentrations of terpenes; synthesis of some terpenes only in treated wines; improved sensory qualities; increased levels of phenolic compounds & [122, 123, 124, 125] \\ \hline \multirow{4}{*}{BTH and chitosan (CHT)} & \multirow{4}{*}{Groppello} & CHT improved the volatile profile, flavor, and taste of Groppello wine, increased total acetals, and alcohols; BTH increased total acetals and esters & [126] \\ \cline{1-1} \cline{  
form [127].