RETICULON-LIKE4 (RTNLB4) Protein Participates in Infection and VirB2 Peptide-Induced Plant Defense Response.

uses the type IV secretion system, which consists of VirB1-B11 and VirD4 proteins, to deliver effectors into plant cells. The effectors manipulate plant proteins to assist in T-DNA transfer, integration, and expression in plant cells. The reticulon-like (RTNLB) proteins are located in the endoplasmic reticulum and are involved in endomembrane trafficking in plant cells. The mutants were recalcitrant to infection, but overexpression of in transgenic plants resulted in hypersusceptibility to transformation, which suggests the involvement of RTNLB4 in infection. The expression of defense-related genes, including , , , and , were less induced in overexpression (O/E) transgenic plants after elf18 peptide treatment. Pretreatment with elf18 peptide decreased -mediated transient expression efficiency more in wild-type seedlings than O/E transgenic plants, which suggests that the induced defense responses in O/E transgenic plants might be affected after bacterial elicitor treatments. Similarly, VirB2 peptide pretreatment reduced transient T-DNA expression in wild-type seedlings to a greater extent than in O/E transgenic seedlings. Furthermore, the VirB2 peptides induced , , and gene expression in wild-type seedlings but not and mutants. The induced defense-related gene expression was lower in O/E transgenic plants than wild-type seedlings after VirB2 peptide treatment. These data suggest that RTNLB4 may participate in elf18 and VirB2 peptide-induced defense responses and may therefore affect the infection process.