Characterization of Mi1,2 Whitefly (Bemisia tabaci) Resistance Gene

摘要

Tomato (Solanum peruvianum) Mi gene provides resistance to whitefly (Bemisia tabaci), potato aphids and nematode making Mi a useful source in integrated pest management program. The aim of this work was to isolate, clone and sequence Mi1,2 gene from S. peruvianum. In addition, physico-chemical identification of amino acids deduced from Mi1,2 gene was done. Secondary (2D) and tertiary (3D) structures of Mi1,2 protein were also predicated. Distinct amplicons of 620, 600, 3300 and 1993 bp were successfully amplified using PCR amplification. The full-length DNA (5.4 kbp) and cDNA (4 kbp) of Mi1,2 gene was isolated using specific primers. Fragments 620 and 600 bp cloned into Escherichia coli XL-1 Blue and sequenced. Sequencing results of both assembled fragments (620 and  600 bp) joined at the overlap region (1440 bp). A BLAST search confirmed  that the DNA sequence from the amplified fragments was Mi1,2 gene. It shared 98% identity and deduced amino acids shared 97% identity with Mi1,2 gene published in GenBank. An Open reading frame (ORF) of Mi1,2 protein encoded for 479 amino acid residues with molecular weight 54.59 KDa and  isoelectric point (PI) 5.52 was calculated using Expasy’s ProtParam server. 2D and 3D structures of Mi1,2 protein was analyzed using SOPMA and Swiss-Prot software, respectively.