Effects of temperature stresses and growth stages on Cry1Ac protein accumulation in BollgardTM cotton

Author(s) : Sajid ur Rahman, Shahid Nazir , Imran Habib, Muhammad Younas, Khalid Mahmood

Digital object identifier:

10.52587/JAF050301

Abstract:

Bacillus thuringiensis (Bt) is a gram-positive soil bacterium that makes crystal proteins toxic for insects, particularly larvae of Diptera and Lepidopteron. Bt genes has been frequently used to develop genetically modified (GM) insect resistant crops. Various factors affecting the gene expression and protein accumulation in GM crops hence, present work was designed to evaluate the effects of temperatures and age on expression pattern of Cry1Ac gene in Bt cotton. Transformation event was verified using digital PCR and the presence of endotoxin was initially confirmed through immuno-strip assay. Toxin accumulation level in top third leaf was investigated using quantitative ELISA after 20 days intervals starting from 60 days. Results showed that protein level gradually increased with plant’s age, and it was maximum at 100 days in plants placed under 35oC. Toxin level declined under all temperature regimes at advanced growth stages and minimal toxin was observed at 25oC. Bt cotton MNH-886 showed higher and stable toxin accumulation in comparison with FH-lalazar even at elevated temperatures and lateral growth stages. These findings demonstrated that expression of Cry1Ac gene is influenced by temperatures and age of the plant, while MNH-886 is a more stable genotype regarding Cry1Ac protein accumulation.