Antioxidant responses of bushy host plants Flemingia semialata and Flemingia macrophylla on inoculation of two different strains of lac insect (Kerria lacca (Kerr))

Bearers of industrially important resinous material shellac secreted by Indian lac insects Kerria lacca (Kerr) grow and survive in a permanent association with certain plant species called host plants. These phloem-feeders display differential host suitability that is dependent on genotype of both plant and insect. Therefore, present study was conducted to evaluate induced biochemical responses in two host plants Flemingia macrophylla and Flemingia semialata upon inoculation by two infra sub-specific forms of this insect. Both host plants displayed differential responses locally in stem tissue and systemically in leaf to two different strains of lac insect. Systemic response is more intense in case of rangeeni inoculation on F. macrophylla and local antioxidant response is higher in F. semialata upon kusmi inoculation. F. semialata has almost twice constitutive H₂O₂ levels in its stem than F. macrophylla which decreased with time upon kusmi inoculation suggesting activated ROS detoxification in this species and absent in F. macrophylla in response to this strain. Basal level of H₂O₂ is high in leaves of F. macrophylla than F. semialata which is contrasting to that observed in stem tissues of both host plants. The intensity of defense response also varied with the strain of insect inoculated on the two host plants. Peroxidase levels in F. macrophylla in response to both strains suggest it is an important ROS detoxification system in this species that plays role in imparting specificity.