Biochemical analysis of metabolites in cotton (Gossypium hirsutum L.) conferring resistance to Leaf hopper Amrasca biguttula biguttula (Ishida)

 The cotton leafhopper Amrasca biguttula biguttula (Ishida) has emerged as a major threat, causing significant yield losses (40-60%). To address this, we aimed to identify cotton genotypes with superior biochemical traits for leafhopper resistance. Various biochemical parameters and elemental composition by EDAX-spectroscopy were analyzed. Field and polyhouse screenings were conducted for host plant resistance (HPR) study. The ANOVA, correlation, and stepwise regression analyses were conducted to assess the traits relationship and their impact on leafhopper resistance. Results showed significant genotype variations (p < 0.05) were observed in biochemical traits and leafhopper injury index. Two verities NDLH1938 and Suraksha and three F1hybrids derived from crosses viz., TVH002 × Suraksha, NDLH1938 × Suraksha, and TVH002 × NDLH1938 were showing significant resistance by recording lower leafhopper population (2.28-5.17), injury index (0.69-0.97), susceptibility index (1.58-5.00) and host preference survival rate (2.21, 2.46). The HPR study suggests that lines are less preferred by the leafhoppers to survive which indicates factors influencing antibiosis. Biochemical profiling revealed that gossypol (r = -0.75), tannins (r = -0.69), and calcium (r = -0.78) were negatively correlated with pest density. It indicates the genotypes with higher levels of gossypol, tannins, and calcium, and lower levels of reducing sugars, total proteins, free amino acids, and chlorophyll exhibited resistance to the leafhopper. Stepwise regression analysis indicated the combined effect of these biochemical traits (R2 = 0.93) in contributing to a high-level of resistance rather than individual traits. Our findings highlight the importance of biochemical traits in influencing leafhopper resistance and the need for comprehensive trait combinations in breeding resistant cotton varieties.