# The Landscape of Integrated Domains of Angiosperm NLR Genes Reveals Continuous Architecture Evolution of Plant Intracellular Immune Receptors

## TL;DR

This study explores how plant immune receptors called NLRs evolve by integrating additional domains, revealing patterns across flowering plants.

## Contribution

The study provides the first comprehensive analysis of integrated domains in NLR genes across 305 angiosperm genomes.

## Key findings

- Up to 38.3% of NLR genes in some species contain integrated domains, with an average of 10.6%.
- 415 integrated domains are homologous to proteins targeted by pathogens, suggesting a decoy function.
- TNL subfamily NLRs have more integrated domains, with DUF3542 being prevalent and linked to structural changes in CNLs.

## Abstract

Nucleotide-binding site-leucine-rich repeat (NLR) proteins are key intracellular immune receptors in plants. Integrated domains (IDs) can occasionally be fused with NLRs, contributing to their functional diversity. However, the diversity and evolutionary patterns of NLR-IDs across angiosperms remain poorly understood. In this study, we analyzed 305 angiosperm genomes and found that the proportion of NLR genes containing IDs (NLR-ID genes) ranges from 0% to 38.3%, with an average of 10.6%. A total of 1226 unique IDs were identified, some of which are widely distributed, while others are specific to particular taxa. Notably, 415 of these IDs are homologous to plant proteins targeted by pathogen effectors, suggesting their role as candidate decoys. Comparative analysis of NLR-IDs in two subfamilies—TIR-NLR (TNL) and CC-NLR (CNL)—revealed that TNL genes have a significantly higher frequency of IDs, with the C-JID and DUF3542 domains being most prevalent. N-terminal fusion of the DUF3542 domain in CNL genes correlates with the loss of the MADA motif. Our findings expand the understanding of NLR-ID diversity and provide insights into the dynamic evolution of NLR protein architecture in angiosperms.