Nutritional, antinutritional and enzymatic basis of antibiosis in maize lines against spotted stem borer, Chilo partellus (Swinhoe)

Plant resistance to herbivores is largely dependent on its ability to defend through biochemical mechanisms. Present study deciphered constitutive and Chilo partellus damage-induced levels of defensive phytochemicals in thirty maize lines, including susceptible and resistant checks. The association of these biochemicals with various indices of C. partellus was computed to comprehend the antibiosis mechanism and group the maize lines in to resistant/susceptible categories. The findings revealed significant variation in antibiosis, growth, and fitness indices of C. partellus when fed on different male and female maize lines, owing to significant differences in the quantity of nutritional (sugars and proteins), antinutritional (phenols, tannins, FRAP and total antioxidants), and enzymatic (TAL, PAL, AO, APX and CAT) components among the test maize lines. Resistant maize lines contained significantly lower quantities of nutritional components, while higher antinutritional and enzymatic components as compared to susceptible lines. Nutritional compounds were positively associated with antibiosis, fecundity and fitness indices, suggesting that these compounds favor growth and reproduction of C. partellus. Conversely, both constitutive and induced levels of antinutritional and enzymatic components were negatively associated with these indices, indicating their detrimental effect on the developmental biology of C. partellus. Additionally, these biochemicals accounted to 70.8 to 79.0% variability in various growth and fitness indices of C. partellus. The A-lines CML 565, AI 501, AI 196, C 70 and DDM 2309-O, and R-lines AI 125, AI 542 and AI 1100 were identified as best sources of resistance, and could be utilized in the breeding program to develop C. partellus resistant maize hybrids.