Study of ATPNP-R1, ATPNP-A and XACPNP in the activation of defense responses against stress

DI PAOLO, V.; GARAVAGLIA, B.S.; GOTTIG, N.; JORGELINA OTTADO

Congreso; LIX Reunion Anual SAIB; 2023

The innate immunity of plants is composed of pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). In the first, recognition of molecular patterns associated with pathogens (PAMPs) occurs through pattern recognition receptors (PRRs) located on the cell surface, with the aim of preventing pathogen invasion and maintaining plant homeostasis. PRRs can be divided into receptor-like kinases (RLKs) and receptor-like proteins (RLPs). Their extracellular portions contain leucine-rich repeats, which perceive microbe- or plant-derived ligands and are differentiated by their intracellular domains.AtPNP-R1 is a plasma membrane-associated receptor, containing an extracellular leucine-rich repeat domain, and it binds the natriuretic peptide AtPNP-A. On the other hand, the hemibiotrophic bacterium Xanthomonas citri subsp. citri encodes a PNP-type protein (XacPNP), which is similar to AtPNP-A. We determined that the relative expression of AtPNP-A and AtPNP-R1 increases after infection with Pseudomonas syringae pv. tomato in Arabidopsis thaliana leaves; and that the damaged area is smaller when XacPNP and AtPNP-R1 are present.We performed a characterization of different mutants and overexpressing lines of the proteins under study against biotic stress. The absence of the receptor under study, AtPNP-R1, leads to greater damage in the infected tissue, suggesting that this receptor plays an important role in activating defense responses in the plant. Additionally, it was observed that this damage is not compensated by overexpression of natriuretic peptides, whether of plant (AtPNP-A) or bacterial (XacPNP) origin. On the other hand, when AtPNP-A is absent, no significant differences were observed compared to the control, and overexpression of the receptor AtPNP-R1 in this parent shows no differences. This illustrates the requirement of the presence of the AtPNP-A - AtPNP-R1 pair for the activation of defense responses against pathogenic attack.