Molecular characterization and phylogenetic studies of a wound-inducible proteinase inhibitor I gene in Lycopersicon species

Abstract

A gene coding for proteinase inhibitor I, whose expression is induced in tomato leaves (Lycopersicon esculentum L. var. Bonny Best) in response to wounding or insect attacks, was isolated from a genomic library and characterized. The nucleotide sequence revealed that the gene is complete and encodes the sequence of an inhibitor I cDNA that was previously isolated from a cDNA library prepared from wound-induced mRNA from tomato leaves. This gene is located 13.1 kilobase pairs (kbp) upstream from an inhibitor II gene. The wound-inducible gene is interrupted by two intervening sequences of 445 and 404 bp, situated within the codons of amino acids 17 and 47, respectively, of the open reading frame. In addition to the presence of putative regulatory sequences, TATAAA and CCACT, two copies of an imperfect direct repeat approximately 100 bp long were identified in the 5'-flanking region. Phylogenetic comparisons of wound-inducible inhibitor I genes within the genomes of various Lycopersicon species revealed that the repeat is found in seven ancestral species of tomato.