The application of Fisher's linear discriminant function highlights the saline eustress observed in sugarcane cultivated in temporary immersion bioreactors

Discriminant analysis is a powerful statistical technique used in plant biotechnology for various applications. In this research, five NaCl concentrations as supplements to the sugarcane culture medium in temporary immersion bioreactors (TIBs) were evaluated. Shoot multiplication rate, shoot cluster fresh weight, and levels of aldehydes, carotenoids, phenolics, and chlorophylls were evaluated. Additionally, soluble phenolic concentration was evaluated in the culture medium. Observations indicated that control TIBs (0 mM NaCl) did not exhibit stress symptoms, whereas TIBs with 200.0 mM NaCl were clearly stressed. These two contrasting treatments were utilized to derive Fisher's linear discriminant function. In contrast, treatments with 50.0, 100.0, and 150.0 mM NaCl displayed intermediate phenotypes. The goal of this report was to determine the NaCl concentrations that induced stress in sugarcane plantlets using discriminant analysis. Fisher's linear discriminant function successfully distinguished between the two categorical groups: non-stressed plantlets (0 mM NaCl) and stressed plantlets (200.0 mM NaCl). Based on the magnitude of the coefficients in Fisher's function, increases in the contents of malondialdehyde and other aldehydes were strong indicators of plant stress. Conversely, increases in soluble phenolics, shoot multiplication rate, and fresh weight of shoot clusters indicated non-stressed plant conditions. Results showed that 50.0 and 100.0 mM NaCl caused only mild stress, classifying these treatments as non-stressed plants. However, sugarcane plantlets cultivated in 150.0 mM NaCl TIBs were classified as stressed plants. The application of discriminant function analysis in this report highlights the saline eustress observed in sugarcane cultivated in TIBs.