Stacking of PRRs in potato to achieve enhanced resistance against Phytophthora infestans

Plants employ pattern recognition receptors (PRRs) to sense pathogen-associated molecular patterns (PAMPs) or apoplastic effectors at the plant cell surface, as well as nucleotide-binding domain leucine-rich-repeat-containing receptors (NLRs) to sense effectors inside the plant cell. Breeding for potato resistance to P. infestans has focused on the use of NLRs, however, these genes are typically quickly overcome since the matching avirulence genes evolve exceptionally quickly. Here, we stacked two PRRs, PERU and RLP23, that recognize the rather conserved Phytophthora PAMPs Pep-13/25 and nlp20, respectively, in the potato cultivar Atlantic, and evaluated their effect on P. infestans resistance. We found that PERU and RLP23 cooperate for the early immune responses like the accumulation of reactive oxygen species (ROS) and production of ethylene by recognizing their corresponding PAMPs. Furthermore, we show that potato plants overexpressing these two PRRs are slightly less affected by P. infestans compared to the single transformants. Together, our data suggest that pyramiding of surface receptors can provide additional enhanced resistance against pathogens, however, more effective or synergistic combinations that may include intracellular NLR receptors should be explored.