A Pathogenesis-Related Protein-Like Gene Is Involved in the Defense Response to the Root Rot Pathogen.

Pathogenesis-related proteins (PRs) are a class of proteins that accumulate in response to biotic and abiotic stresses to protect plants from damage. In this study, a gene encoding a PR-like protein (PnPR-like) was isolated from , which is used in traditional Chinese herbal medicines. An analysis of gene expression in indicated that was responsive to an infection by the root rot pathogen . The expression of this gene was induced by several signaling molecules, including methyl jasmonate, ethephon, hydrogen peroxide, and salicylic acid. The fusion gene was transiently expressed in onion () epidermal cells, which revealed that PnPR-like is a cytoplasmic protein. The purified recombinant protein expressed in had antifungal effects on and as well as inhibited the spore germination of . Additionally, the ribonuclease (RNase) activity of the recombinant PnPR-like protein was revealed. The gene was inserted into tobacco () to verify its function. The gene was stably expressed in T transgenic tobacco plants, which exhibited more RNase activity and greater disease resistance than the wild-type tobacco. Moreover, the transient expression of hairpin RNA targeting in leaves increased the susceptibility to and decreased the expression level. In conclusion, the cytoplasmic protein PnPR-like, which has RNase activity, is involved in the g defense response .