Molecular characterization of mannose specific lectin gene,ASAL1 from Garlic leaf (Allium sativumL.)

Abstract

Plant lectins, especially monocot mannose-binding lectins (MMBLs) play significant roles in plant defense against sap sucking insects. In the present study, lectin gene (ASAL1) from garlic leaves (Allium sativum L. leaf agglutinin) was isolated, sequenced and characterized using various bioinformatics tools. Full-length cDNA of naturally occurring MMBLs was synthesized from garlic leaf RNA (leaf agglutinin, ASAL1) using RT-PCR and was amplified with gene specific primers designed corresponding to the conserved regions of the nucleotide sequences of garlic lectin sequences already available at NCBI. The amplified cDNA was sequenced. Sequence analysis revealed 369bp ORF including C-terminal stop codon, encoding a putative polypeptide of 122 amino acids (13kD) in ASAL1. The candidate gene sequence (ASAL1) was 33 nucleotides more and showed eight nucleotide changes than the previously reported garlic leaf lectin gene sequence of 339bp with accession number EU252577. ASAL1 gene sequence showed maximum (98%) identity with Allium sativum lectin mRNA complete cds having accession number DQ525625.1. In ASAL1 nine amino acid residues were glycosylated (both N and O linked). A putative conserved domain (4–113) was detected in the deduced amino acid sequence. ASAL1 gene is bulb type mannose binding lectin (β-lectin). Phylogenetic analysis revealed that ASAL1 falls in close relation with ACA.