WIP1, A WOUND-INDUCIBLE GENE FROM MAIZE WITH HOMOLOGY TO BOWMAN-BIRK PROTEINASE-INHIBITORS

We have cloned and sequenced a wound-inducible cDNA clone designated WIP1 (for wound-induced protein) from maize coleoptiles. It was isolated by differential screening of a cDNA library prepared from excised maize coleoptile segments. The deduced amino acid sequence predicts a secretory, cysteine-rich protein of 102 residues with a calculated molecular mass of 11 kDa and a typical N-terminal signal sequence. The protein has about 30% identity with various Bowman-Birk type proteinase inhibitors. Most interestingly, it is novel in that it is double-headed with exclusive specificity for chymotrypsin. WIP1 is strongly wound-induced in contrast to other members of the Bowman-Birk proteinase inhibitor family, -which occur in seeds and are regulated during development. The response is fast, similar to defence-induced genes, and measurable as early as 30 min after wounding. Induction can also be evoked in the intact coleoptiles and the signal is systemically transmitted in the coleoptile to adjacent regions of the wounded area. Isolation and analysis of the corresponding genomic clone reveals that WIP1 contains an intron of 90 nucleotides.