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 <i>Phytophthora infestans</i>, poses a major threat to global potato production. The oomycete PAMP, <i>P. infestans</i> cell wall ceramide D, triggers reactive oxygen species (ROS) production in potato and <i>Arabidopsis</i>. It is specifically recognized by the lectin receptor-like kinase RESISTANT TO DFPM-INHIBITION OF ABSCISIC ACID SIGNALING 2 (RDA2) in <i>Arabidopsis</i>. Treatment with <i>P. infestans</i> ceramide D enhances potato resistance against <i>P. infestans</i>. However, the function of RDA2 homologs in potato remains uncharacterized. Herein, potato <i>RDA2</i> genes were identified through sequence alignment analysis. Their expression levels were subsequently measured in a potato inbred line infected with <i>P. infestans</i>. Notably, transient expression of <i>StRDA2A</i>, but not its kinase-dead mutant <i>StRDA2A^K543M</i>, caused cell death and enhanced disease resistance in <i>Nicotiana benthamiana</i>. 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 <i>P. infestans</i>.