Quantifying Proline and Soluble Sugars in Plants

Approximately 100 mg of fresh leaves and roots was homogenized for determination of proline content following the manufacturer’s instructions (A107-1-1, Nanjing Jiancheng Bioengineering Institute, Nanjing, China), and the absorbance was measured at 520 nm. For the analysis of soluble sugars, approximately 0.1 g of fresh samples was homogenized in 1 ml ddH₂O with a glass homogenizer. The tubes were boiled at 95°C for 10 min and cooled with tap water. After cooling, the homogenate was centrifuged at 4,000 × g for 10 min. Thereafter, the supernatant was diluted with ddH₂O at 1:9. The diluted extracts were used for determination of soluble sugar content using a commercially available test kit (A145-1-1, Nanjing Jiancheng Bioengineering Institute, Nanjing, China). Finally, the absorbance was measured at 620 nm and the soluble sugar concentration expressed and the results expressed in the fresh weight (FW) basis (Dai et al., 2018 (link); Kumar et al., 2021 (link)).