Proteases inhibitors of Glycine max seeds decrease digestive enzyme activity of Nezara viridula

MEDINA, V; SARDOY, P; BARNETO, J; BARRIGA, LG; PAGANO, E; ZAVALA J.A.

Potrero de los Funes

Congreso; XLVII Reunión anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2011

Although currently pests are controlled by transgenic crops, no transgenic soybeans (G. max) can resist stinkbugs (N. viridula) herbivory. These bugs damage young pods and decrease crop yield. However, soybean naturally responds to insect herbivory by up-regulating anti-herbivore defenses, such as protease inhibitors (PIs), which affect digestion and amino acid assimilation in the gut of insects. Our aim was to determine the effects of soybean’s PIs on proteolytic activity in the gut of stinkbugs. Field collected insects were kept on control diet for 15d, and then placed for 72h on two soybean genotypes, Williams and a resistant cultivar (PI227687) to insect herbivory. Total and cysteine proteases activity in the gut of stinkbugs were decreased after 72h of feeding on soybean pods. This activities decresed 43% and 33% when stinkbugs fed on cv Williams, and 72% and 66% on cv PI227687, compared to the control. Cystein proteases showed the highest activity in the insect gut extracts (30-45%), followed by the aspartyl and serine proteases (10-30%). Experiments with soybean PI showed that stinkbugs that fed on control diet had higher levels of sensitive digestive proteases to PIs than those that fed on the PI227687. Our results suggest that although digestive enzymes of stinkbug can be inhibited by soybean PIs, these insect compensate the lost activity by inducing enzymes resistance against PIs.