Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 23, 2011
Publication Date: N/A
Technical Abstract: ZmPep1 (Zea mays elicitor peptide 1) is a bioactive peptide signal encoded by a previously uncharacterized Zea mays gene. The gene, ZmPROPEP1, was identified as an ortholog of the Arabidopsis gene AtPROPEP1, which encodes the precursor protein of elicitor peptide 1 (AtPep1). Together with its receptors, AtPEPR1 and AtPEPR2, the AtPep1 peptide regulates pathogen defense responses in Arabidopsis, and enhances resistance to both Pythium irregulare and Pseudomonas syringae. Candidate gene orthologs to AtPROPEP1 have been identified from many crop species by sequence similarity; however, prior to this study, it was not known whether the respective peptides encoded by these orthologs were active signals regulating innate immunity. We show that in maize, the ZmPep1 peptide is functionally homologous to AtPep1. ZmPep1 activates synthesis of the defense-related hormones jasmonic acid (JA) and ethylene (ET) and induces expression of both genes encoding defense proteins and BX1, a gene required for the biosynthesis of benzoxazinoid defenses. Furthermore, plants treated with ZmPep1 accumulate 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside (HDMBOA-Glc) in leaves. To establish whether ZmPep1-induced defenses affect resistance, maize plants were pretreated with the peptide prior to inoculation with fungal pathogens. As quantified through measurements of cell death and lesion severity, ZmPep1 pretreatment enhanced resistance to both southern leaf blight and anthracnose stalk rot caused by Cochliobolis heterostrophus and Colletotrichum graminicola respectively. Our data indicates that peptides belonging to the elicitor peptide (Pep) family have conserved function across plant species as endogenous regulators of innate immunity and may have potential for enhancing disease resistance in crops.