Identification and Functional Analysis of Potato Receptor Kinase RDA2 Proteins

Plants utilize cell surface pattern recognition receptors to recognize pathogen-associated molecular patterns (PAMPs) and activate pattern-triggered immunity (PTI) responses. Late blight, caused by the oomycete plant pathogen Phytophthora infestans, poses a major threat to global potato production. The oomycete PAMP, P. infestans cell wall ceramide D, triggers reactive oxygen species (ROS) production in potato and Arabidopsis. It is specifically recognized by the lectin receptor-like kinase RESISTANT TO DFPM-INHIBITION OF ABSCISIC ACID SIGNALING 2 (RDA2) in Arabidopsis. Treatment with P. infestans ceramide D enhances potato resistance against P. infestans. However, the function of RDA2 homologs in potato remains uncharacterized. Herein, potato RDA2 genes were identified through sequence alignment analysis. Their expression levels were subsequently measured in a potato inbred line infected with P. infestans. Notably, transient expression of StRDA2A, but not its kinase-dead mutant StRDA2A^K543M, caused cell death and enhanced disease resistance in Nicotiana benthamiana. Additionally, two RXLR-type effector proteins significantly inhibited StRDA2A-induced cell death. The findings of this study suggest that potato receptor kinase RDA2 proteins confer disease resistance, which is attenuated by RXLR effectors secreted by P. infestans.