Multivariate chemometric discrimination of mango genotypes for fruit fly resistance using structural and biochemical traits

Mango production is severely hampered by the oriental fruit fly, Bactrocera dorsalis (Hendel), which results in significant yield and quality losses. The current investigation used multivariate chemometric techniques to distinguish between resistant and susceptible mango genotypes and to uncover physio-structural and biochemical characteristics linked to fruit fly resistance. Under pre and post-infestation stages, eight mango genotypes with different fruit fly responses were assessed for infestation parameters, fruit physical characteristics, biochemical components, antioxidant capacity, and defense-related enzyme activities. Resistant genotypes (Appemidi, Langra, Amrapali and EC-95862) exhibited greater peel thickness (0.17–0.73 mm), higher peel and pulp firmness, elevated phenolic content (6.71–36.4 mg g⁻¹), tannins (6.43–42.4 mg 100 g⁻¹), antioxidant activity (FRAP: 6.57–38.6 µmol TE 100 g⁻¹), and increased PAL, TAL, PPO, POD, and CAT activities compared with susceptible genotypes. Fruit fly infestation showed strong negative correlations with total phenolics (r = − 0.958 to − 0.815), tannins (r = − 0.965 to − 0.968), flavonoids (r = − 0.932 to − 0.975), PAL (r = − 0.908 to − 0.947), TAL (r = − 0.875 to − 0.959), peel thickness (r = − 0.802), and fruit firmness (r = − 0.784), whereas total sugars and total soluble solids were positively associated with susceptibility. Principal component analysis explained 77.6% and 80.7% of the total variation in peel and pulp datasets, respectively, and clearly separated resistant and susceptible genotypes. PLS-DA and OPLS-DA further validated genotype classification, with OPLS-DA models exhibiting satisfactory predictive ability Q² = 0.894 and 0.915 for peel and pulp, respectively. Integrated physio-structural, biochemical, and chemometric analyses effectively distinguished fruit fly-resistant and susceptible mango genotypes. The study identified peel thickness, firmness, phenolics, tannins, flavonoids, antioxidant activity, and defense-related enzymes as key candidate resistance-associated traits against Bactrocera dorsalis. The identified bioactive compounds and defence-related enzymes show promise for early screening and characterization of fruit fly resistance in mango and may support resistance breeding, subject to validation across larger and independent germplasm populations. Resistant mango genotypes showed distinct physico-structural and biochemical profiles. Fruit-fly infestation was negatively associated with phenolics, tannins, flavonoids and antioxidant activity. PAL, TAL, PPO, POD and CAT activities were associated with resistant genotype profiles. PCA, PLS-DA and OPLS-DA discriminated resistant and susceptible genotypes. Peel thickness, firmness and phenolic traits emerged as candidate resistance-associated biomarkers.