ABSTRACTWe report the identification, characterization, and gene cloning of a novel protein elicitor (PeBL1) secreted fromBrevibacillus laterosporusstrain A60. Through a purification process consisting of ion-exchange chromatography and high-performance liquid chromatography (HPLC), we isolated a protein that was identified by electrospray ionization quadrupole time of flight tandem mass spectrometry (ESI–Q-TOF–MS-MS). The 351-bp PeBL1 gene produces a 12,833-Da protein with 116 amino acids that contains a 30-residue signal peptide. The PeBL1 protein was expressed inEscherichia coli. The recombinant protein can induce a typical hypersensitive response (HR) and systemic resistance inNicotiana benthamiana, like the endogenous protein. PeBL1-treatedN. benthamianaexhibited strong resistance to the infection of tobacco mosaic virus-green fluorescent protein (TMV-GFP) andPseudomonas syringaepv. tabaci compared to controlN. benthamiana. In addition, PeBL1 triggered a cascade of events that resulted in defense responses in plants, including reactive oxygen species (ROS) production, extracellular-medium alkalization, phenolic-compound deposition, and expression of several defense-related genes. Real-time quantitative-PCR analysis indicated that the known defense-related genesPR-1,PR-5,PDF1.2,NPR1, andPALwere upregulated to varying degrees by PeBL1. This research not only provides insights into the mechanism by which beneficial bacteria activate plant systemic resistance, but also sheds new light on a novel strategy for biocontrol using strain A60.
A Novel Protein Elicitor (PaNie) from Pythium aphanidermatum Induces Multiple Defense Responses in Carrot, Arabidopsis, and Tobacco
