Plastids targeted BNT1 immune receptor implicated in the organelle-associated defense responses in Arabidopsis.

MICAELA Y. PEPPINO MARGUTTI; ARIEL HERRERA-VASQUEZ; ANA PAULA CISLAGHI; PALOMEQUE JULIETA; FRANCISCO BELLINO; ALVAREZ, MARÍA ELENA; FRANCISCA BLANCO-HERRERA; CECCHINI, NICOLAS M

Congreso; RAFV Conference 2023 XXXIV Argentinian Meeting of Plant Physiology; 2023

Nucleotide-binding leucine-rich repeat receptors (NLRs) play a critical role in the plant immune system, conferring resistance against many diseases. While the functional diversity of NLRs within different cellular compartments has been extensively studied, their role in plastids, essential organelles for an effective defense against pathogens, has remained unexplored. In this study, we present in silico evidence revealing the presence of an N-terminal signal responsible for targeting an Arabidopsis NLR from the TNL family to the plastid envelope. We studied the subcellular localization of BNT1, confirming their presence in the plastid envelope. Moreover, expression analysis showed that the relative abundance of BNT1 is influenced by bacterial infection, with specific patterns of expression observed in epidermal tissue, which is proposed to play a vital role in the immunity against these invaders. The functional significance of the BNT1 was further studied by evaluating their impact on plant resistance against Pseudomonas spp. Strikingly, mutant plants deficient in this NLR exhibited altered resistance to the bacteria. To gain insights into the underlying molecular mechanisms, we assessed chloroplast redox changes in response to bacterial infections using the redox-sensitive green fluorescent protein (roGFP) ratiometric system. The results show that the NLR-mediated responses are linked to chloroplast redox regulation. Our study shows for the first time an NLR located in chloroplasts and presents evidence for the involvement of NLRs in plastid-mediated immunity, expanding our understanding of the plant immune system's complex regulation.