Effect of Oxalic and Malic Acids in Chickpea Leaf Exudates on the Activity of Cry1Ac towards Pod Borer

February 13, 2013

Scientists have expressed the genes from common soil bacterium Bacillus thuringiensis in chickpea to produce toxins that makes the plant resistant to pod borer (Helicoverpa armiegera). However, some researchers perceive that the acidic exudates in chickpea leaves may affect the conversion of protoxin to toxin in the insect midgut, which can lead to the reduction of toxin effectiveness. Thus, V. Surekha Devi from the International Crops Institute of the Semi-Arid Tropics (ICRISAT) and colleagues investigated the effect of organic acids (oxalic acid and malic acid) from chickpea on the activity and binding of Bt toxin Cry1Ac to brush border membrane vesicles (BBMV) in the midgut of the pod borer.

Results showed that the organic acids in amounts present in the chickpea leaves had no effect on the biological activity of the Bt toxin towards pod borer larvae. When the amount of organic acids were increased, the concentration of Bt toxin was decreased in the midgut of the larvae. Larval weights were also noted to be reduced when they were fed with diets containing organic acid, with or without the presence of Bt toxin.

Read the abstract at http://www.sciencedirect.com/science/article/pii/S0022191013000255