Uniquely Regulated Proteinase Inhibitor I Gene in a Wild Tomato Species

A uniquely regulated proteinase inhibitor I gene was isolated from the wild tomato species Lycopersicon peruvianum (L.) Mill. (LA 107) and characterized. The inhibitor gene is wound-inducible in leaves and is expressed in unripe fruit during development. The gene (lambda clone 1) is present on a 15.5 kilobase pair Sal 1-SalI genomic DNA fragment. Southern blot analysis of L. peruvianum genomic DNA shows only one strongly hybridizing DNA fragment to probes derived from lambda clone 1. S1 nuclease protection experiments and Northern analyses confirm that this gene is both wound-inducible in leaves and developmentally regulated in young unripe fruit. These observations are supported by comparisons of the 5'-flanking DNA sequences of the L. peruvianum inhibitor I gene with known elicitor responsive cis-acting sequences. The transcriptional regulation of the lambda clone 1 inhibitor I gene in leaves of wounded plants and in developing unripe fruit indicates that the gene contains unique complex regulating elements. These elements respond to both environmental and developmental tissue-specific signals that can regulate proteinase inhibitor synthesis to protect the tissues of this wild species of tomato against predators and pathogens.