Wound-induced accumulation of mRNA containing a hevein sequence in laticifers of rubber tree (Hevea brasiliensis)

Abstract

Hevein is a chitin-binding protein that is present in laticifers of the rubber tree (Hevea brasiliensis). A cDNA clone (HEV1) encoding hevein was isolated by using the polymerase chain reaction with mixed oligonucleotides corresponding to two regions of hevein as primers and a Hevea latex cDNA library as a template. HEV1 is 1018 base pairs long and includes an open reading frame of 204 amino acids. The deduced amino acid sequence contains a putative signal sequence of 17 amino acid residues followed by a 187-amino acid polypeptide. This polypeptide has two striking features. The amino-terminal region (43 amino acids) is identical to hevein and shows homology to several chitin-binding proteins and to the amino termini of wound-inducible proteins in potato and poplar. The carboxyl-terminal portion of the polypeptide (144 amino acids) is 74-79% homologous to the carboxyl-terminal region of wound-inducible genes of potato. Wounding, as well as application of the plant hormones abscisic acid and ethylene, resulted in accumulation of hevein transcripts in leaves, stems, and latex but not in roots.