*2.9. Measurements of the Levels of Water-Soluble Proteins, Proline, Soluble Sugars, Free Amino Acids, and Carbohydrates*

The content of water-soluble proteins was quantified in the extracts used for enzyme activity determination following the method of Bradford [29] using bovine serum albumin as a protein standard. The level of proline (Pro) was determined spectrophotometrically by an acid ninhydrin-based technique, following the procedure reported by Bates et al. [30]. The method used by Somogyi [31] was followed for the quantification of total soluble sugars. The total free amino acid content of the leaf samples was determined with the aid of ninhydrin, in accordance with the protocol proposed by Lee and Takahashi [32]. Following the methodology of Dubios et al. [33], the phenol-sulfuric acid method was used for the determination of total carbohydrate contents in soybean leaves.

#### *2.10. Statistical Analysis*

Data obtained from four biological replicates per treatment were analyzed by oneway analysis of variance (ANOVA). The means were calculated from biological repeats and compared among the treatments using the least significant difference (LSD) test at *p* < 0.05 with the aid of Statistix 10 software. Different alphabetical letters symbolize significant variations among the control, drought, and ethanol treatments. Heatmap of the fold-change values of different phenotypical and biochemical parameters was created using R studio 1.4.1717.

#### **3. Results**
