Quantitative Analysis on Expression of Insecticidal Crystal Proteins in Different Plant Parts of BG-II Cotton Hybrids at Various Phenological Stages

Abstract

The use of insecticidal crystal proteins (Cry proteins) in Bollgard-II cotton (Gossypium hirsutum) hybrids enhances insect control, particularly against bollworms. The combined expression of Cry1Ac and Cry2Ab protein increases the overall performance of Bt-cotton plants. Cry proteins content varies in different parts of the cotton plant, such as leaves, squares and bolls. This variability in protein expressions and the frequent decline in the Cry proteins content in various plant parts at different crop phenological stages is one of the reasons for the survival of pest populations on BG-II cotton hybrids. Using 96 ELISA kits, Cry1Ac and Cry2Ab concentrations were measured in leaves, squares, and bolls at 30, 60, 90, and 120 days after sowing (DAS) over 3 years. Protein content varied across plant parts, peaking at 90 DAS, and declining at 120 DAS. Cry1Ac expression was lower than Cry 2Ab, with leaves exhibiting the highest expression. The highest Cry protein expression occurred in leaves across the 3 years. Regardless of plant parts, Cry1Ac and Cry2Ab content were highest at 90 DAS, providing insights into protein expression patterns and feeding preferences, contributing to responsive insect-pest control in Bt-cotton. These results help understand the pattern of Cry proteins expression in different plant parts vis-à-vis feeding preference, which further contributes to providing valuable knowledge of responsive control for insect-pest population in Bt-cotton cultivars.