Isolation and characterization of a mannose-binding insecticidal lectin gene from Allium sativum (garlic) and its putative role in insect resistance using bioinformatics tools.

Monocot mannose-binding lectins (MMBLs) or agglutinins are an extended superfamily of structurally and evolutionarily related proteins. They play important roles in plant defenses. Here we describe the synthesis of full-length cDNA of monocot mannose-binding insecticidal agglutinin isolated from Allium sativum, a traditional herb known to be of great applications in Africa, using reverse transcription polymerase chain reaction (RT-PCR) with specific primers designed based on the insecticidal sequence (NCBI primary accession no. AY866499.1). Sequence analysis revealed a 327bp open reading frame (ORF) encoding a putative 108-aa agglutinin precursor with a C-terminal domain. Multiple alignments of BLEC1 amino acids with those of eight other MMBLs revealed three highly conserved domains among them, indicating BLEC1 belongs to a member of the MMBL superfamily. Tertiary structure analysis showed that BLEC1 had three potential equal mannose-binding sites. Phylogenetic analysis indicated that 20 MMBLs including BLEC1 belonged to an extended superfamily. Gene ontology analyses indicate one biological process with GO ID: 0006952 representing defense response, with two secondary IDs GO: 0002217 GO: 0042829. The child terms has both negative and positive regulation some of which include GO: 0002242 defense response to parasitic plant and GO: 0002213 defense response to insect. The cloning and characterization of BLEC1 will enable us to study its potential use in plant genetic engineering in the development of insect resistance plant.