Systemin.

摘要

Systemin is an 18 amino acid peptide hormone that induces expression of defense genes in plants wounded mechanically or by predators including herbivores, insects, bacteria and viruses. The precursor for systemin is encoded as a 200 amino acid prosystemin molecule that has the systemin peptide sequence located near the carboxy-terminus. Both a 951 bp cDNA for prosystemin and 4526 bp genomic DNA were cloned and the organization of the gene was determined. Transgenic plants constructed with antisense prosystemin DNA fail to mount a defensive response to wounding. Transgenic plants constructed with increased copy number of prosystemin genes exhibit increase resistance to wounding. A tomato systemin polypeptide has an amino acid sequence NH3-AVQSKPPSKRDPPKMQTD-COO-.