Characterization of a Highly Potent Insecticidal Lectin from Colocasia esculenta Tuber and Cloning of Its Coding Sequence

Hemipteran insects are the most devastating pest for different crops of high economic value. Colocasia esculenta tuber agglutinin (CEA), a mannose binding monocot lectin from araceae family was previously reported by the present group to be effective against some members of this class of pests. In the present study, efficacy of this potent lectin has been extended to cotton aphid (Aphis gossypii) which is becoming a highly damaging pest of cotton in recent days. Because, like other aphids, A. gossypii not only extracts the phloem fluid but also transmit disease causing viruses and add to the high degree of yield loss. Efficacy of the lectin on cotton aphid as well as other hemipteran insects prompted us further to clone the protein coding gene. Very little sequence information of this gene was available in the database. Hence, attempt had been made to study the protein through liquid chromatography-tandem mass spectrometry (LC-MS/MS) to have the detailed peptide information. On the basis of the peptide homology information obtained from LC-MS/MS the complete coding sequence of CEA was determined. The coding sequence corresponding to CEA was cloned further using primers designed on the basis of above information and genome walk technology for its potential utilisation in insect management programme.