The novel peptide NbPPI1 identified from Nicotiana benthamiana triggers immune responses and enhances resistance against Phytophthora pathogens

• 来源期刊: 植物学报（英文版）
• 年，卷（期）: 2021,（5）
• 所属期刊栏目: Plant-biotic Interactions
• 页码范围: 961-976
• 页数: 16页
• 语种: 英文

摘要

In plants,recognition of small secreted peptides,such as damage/danger-associated molecular patterns (DAMPs),regulates diverse processes,including stress and immune responses.Here,we identified an SGPS (Ser-Gly-Pro-Ser) motif-containing peptide,Nicotiana tabacum NtPROPPI,and its two homologs in Nicotiana benthamiana,NbPROPPI1 and NbPROPPI2.Phytophthora parasitica infection and salicylic acid (SA) treatment induced NbPROPPI1/2 expression.Moreover,SignalP predicted that the 89-amino acid NtPROPPI includes a 24-amino acid N-terminal signal peptide and NbPROPPI1/2-GFP fusion proteins were mainly localized to the periplasm.Transient expression of NbPROPPI1/2 inhibited P.parasitica colonization,and NbPROPPI1/2 knockdown rendered plants more susceptible to P.parasitica.An eight-amino-acid segment in the NbPROPPI1 C-terminus was essential for its immune function and a synthetic 20-residue peptide,NbPPI1,derived from the C-terminus of NbPROPPI1 provoked significant immune responses in N.benthamiana.These responses led to enhanced accumulation of reactive oxygen species,activation of mitogen-activated protein kinases,and up-regulation of the defense genes FIg22-induced receptor-like kinase (FRK) and WRKY DNA-binding protein 33 (WRKY33).The NbPPI1-induced defense responses require Brassinosteroid insensitive 1-associated receptor kinase 1 (BAK1).These results suggest that NbPPI1 functions as a DAMP in N.benthamiana;this novel DAMP provides a potentially useful target for improving plant resistance to Pytophthora pathogens.