Using the pathogens tricks to gain resistance
Plants and pathogens are involved in a tug of war. Who wins lives to fight another day. A lot of that fight takes place in the extracellular space, the space between cells, in plant tissues. There plants secrete an arsenal of defence molecules, like proteases, glycosidases and lipases. And the pathogens, they do the same.
One of the proteases whose working is required for resistance against pathogens are the PLCPs. For the tomato infecting oomycete Phytophthora infestans this is no problem. It brings along PLCP inhibiting proteins called EpiCs. And now comes the twist, this oomycete also brings its own PLCP type proteases.
This last bit intrigued a group of researchers in the UK. They set out to characterise the oomycete PLCPs. Two of those stood out and were studied in greater detail, Pain1, and Pain2. Sequence analysis along with activity analysis suggest that these proteases have different targets. Further testing also indicated that Pain1 and Pain2 promote infection of the oomycete.
Pain1 and Pain2 are not inhibited by EpiCs
Then the researchers asked themselves how these pathogen proteases could do their work while there also were the pathogens EpiCs on the loose. To investigate this, they found out that while the tomato PLCP C14 was inhibited by the oomycete EpiC, the oomycete Pain1 and Pain2 where not.
Subsequently, the researchers turned to protein-protein interaction models of EpiC and Pain1, and of EpiC and C14. By comparing both models, the researchers found a group of seven amino acids that are important for the interaction with EpiC. Those seven amino acids were different between Pain1 and C14.
Next the researchers changed these seven amino acids from C14 to those seen in Pain1. This engineered C14 did have comparable activity levels as normal C14, so the protein could still do its job. Then the researchers observed the effect of this engineered C14 on infection with Phytophthora infestans. While plants with non-engineered C14 where happily infected by Phytophthora infestans, plants with engineered C14 were less infected.
This study shows that by really finding out what each of the separate components that are part of a pathogen’s arsenal does can help plant breeders to give plants an edge in the tug of war between plants and pathogens.
Literature
J. Huang, A. Penrose, L. Ossorio Carballo, & R.A.L. van der Hoorn, Pathogen-inspired engineering of plant protease enhances late blight resistance, Proc. Natl. Acad. Sci. U.S.A. 123 (2) e2524700123, https://doi.org/10.1073/pnas.2524700123 (2026).
Plant en Zo 