Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 12, 2010
Publication Date: N/A
Technical Abstract: ZmPEP1 is a peptide signal encoded by a previously uncharacterized maize gene that we have named ZmPROPEP1. The ZmPROPEP1 gene was identified by homology to the Arabidopsis AtPROPEP1 gene that encodes the precursor protein to the peptide signal AtPEP1. Together with its receptors, AtPEPR1 and AtPEPR2, AtPEP1 acts to activate and amplify innate immune responses in Arabidopsis, inducing transcription of signaling and pathogen defense genes. This activity of AtPEP1 enhances plant resistance to both Pythium irregulare and Pseudomonas syringae. Although genes homologous to AtPROPEP1 have been identified from a variety of crop species, prior to this study, activities of the respective peptides remain unknown. Several lines of evidence indicate that ZmPROPEP1 and the ZmPEP1 peptide play a role similar to AtPEP1 in defensive signaling that could potentially be manipulated to enhance disease resistance in maize. ZmPROPEP1 gene expression is inducible in maize leaves treated with jasmonic acid (JA) or with synthetic ZmPEP1. Supplying maize leaves with the ZmPEP1 peptide also activates transcription of several genes encoding JA biosynthetic enzymes, and triggers the accumulation of endogenous JA within the leaf. Additionally, treatment of leaves with ZmPEP1 induces an array of genes encoding proteins related to pathogen defense. These results indicate that ZmPEP1 regulates pathogen defense responses in maize through modulation of jasmonic acid signaling. To ascertain whether ZmPEP1 activation of defense in leaves leads to enhanced resistance to foliar pathogens, the effects of ZmPEP1 pretreatment on resistance to the fungi Cochliobolus heterostrophus and Colletotrichum graminicola, the causative agents of Southern and Anthracnose leaf blights, is currently under evaluation.