Analysis of an integrative synthetic variable in plant biotechnology experiments with multiple dependent outcomes
摘要
An integrative synthetic variable, derived via principal component analysis (PCA), was used to condense ten physiological and biochemical indicators into a single, uncorrelated metric (PC1), enhancing interpretability and enabling comparative analysis of plant stress responses. This study focused on salinity and drought—major constraints to sugarcane and pineapple productivity—by evaluating NaCl and mannitol induced stress in temporary immersion bioreactors (TIBs). Twenty treatment combinations were tested across three experimental factors: species (sugarcane, pineapple), stressor type (NaCl, mannitol), and concentration (0 to 200 mM). PCA revealed that PC1 explained 54.04% of the total variance and effectively captured trade-offs between growth traits and stress markers. Sugarcane exhibited broad physiological plasticity: NaCl reduced shoot multiplication (approximately 33.8 to 3.3) while increasing carotenoids (13.1 to 80.9 µg g FW⁻1), and mannitol elevated soluble phenolics in the medium (7.8 to 39.1 µg mL⁻1). Pineapple showed lower variability, with consistently low chlorophyll (≤ 60.5 µg g FW⁻1) and negative PC1 scores. Three-way ANOVA confirmed significant effects of all main factors and their interaction. PC1 values increased progressively in sugarcane under mannitol, indicating metabolic activation, while pineapple maintained a static, conservative profile. These findings validate PC1 as a robust integrative metric and position Sugarcane as a suitable model for osmotic stress adaptation.