Purification, characterization and bioefficacy of legume lectins against mustard aphid

Lectins are carbohydrate binding proteins which perform diverse roles in plants. One important role is in plant defense. These proteins hold great potential as entomotoxic proteins as a part of integrated pest management.

Lectins were purified and characterized from seeds of two legumes, Glycine max-Soybean and Lens culinaris-Lentil, employing ammonium sulfate fractionation and ion exchange chromatography. Bioefficacy of the purified lectins was evaluated against mustard aphid.

Lectins isolated from seeds of soybean (Glycine max agglutinin GMA-I, II) and lentil (Lens culinaris agglutinin LCA-I) were purified upto 9.30 (GMA-I), 4.60 (GMA-II) and 8.70 (LCA-I) fold, respectively. Lectin characterization revealed that soybean agglutinin and lentil agglutinin were specific towards D-Galactose and D-mannose, respectively. Insect bioassay was carried out with five different concentrations (10, 20, 30, 40, 50 μg/ml) of purified lectins of soybean and lentil against mustard aphid. The lethal concentration LC₅₀ value for GMA-I was obtained as 32.1 μg/ml with a 95% confidential interval of 18.2 to 40.5 μg/ml and that of LCA-I was 19.1 μg/ ml with a 95% confidential interval of 9.3 to 26.8 μg/ml. Lentil lectin (LCA-I) with lower LC₅₀ value, was found to be the potential candidate for integrated pest management.