Fig. 1: The distribution of cell-surface receptors in plants.

a–g Ectodomain structure of an LRR receptor. a a G-lectin receptor, b an L-lectin receptor, c a LysM receptor, d a Malectin receptor, e a WAK receptor, f and a Duf26 receptor g. Structures of FLS2, CERK1, and FERONIA were published^55,95,96. Structures of LORE, DORN1, WAK1 and CRK28 were predicted by Alphafold2*⁹⁷. Ectodomains are visualized in iCn3D⁹⁸. h Schematic displays the domain architecture of different classes of receptor-like kinase (RLKs) and receptor-like proteins (RLP) in plants. Arrows represent the ligands that these receptor classes have been reported to perceive or recognize. The upper box defines the ligands recognized by different receptors. The lower box defines the domains within the receptor classes. Note that these receptors may be able to recognise other unidentified ligands. For more information, see Supplementary Fig. 1. i Ectodomain distribution of RLKs in plants. Each fraction represents the percentage (%) of ectodomain out of all the RLKs from 350 species (177,645). j Ectodomain distribution of RLP in plants. Each fraction represents the percentage (%) of ectodomains out of all the RLPs with those seven ectodomains (41,144). k Table of RLKs and RLPs with LRR (red), G-lectin (orange), WAK (turquoise), Duf26 (blue), L-lectin (purple), LysM (green), and Malectin (magenta) ectodomains. Characterised receptors involved in microbial interaction (bacteria icon), reproduction (flower icon), and development (leaf icon) are indicated with light green boxes. Grey boxes indicate that the receptor class has not been reported to be involved in that biological process. For details, refer to Supplementary Fig. 1. Correlations between different classes of cell-surface receptors and NB-ARC in 300 angiosperms are indicated with bars. Strong positive correlations are indicated by extension to the light green area (Pearson’s r > 0.6) and medium positive correlations are within the yellow area (Pearson’s r between 0.3 and 0.6). Expression level^ refers to the expression of each class of cell-surface receptors during NLR-triggered immunity (NTI) in Arabidopsis thaliana. Light blue area represents increased expression and light pink area represents decreased expression during NTI. X-axis values represent log₂ (fold change during ETI relative to untreated samples). Boxplot elements: center line, median; bounds of box, 25th and 75th percentiles; whiskers, 1.5 × IQR from 25th and 75th percentiles. Number of cell-surface receptors (n) analysed in the RNA-seq data: LRR-RLK, n  =  159; LRR-RLP, n  =  42; G-lectin-RLK, n  =  29; G-lectin-RLP, n  =  1; WAK-RLK, n  =  18; WAK-RLP, n  =  10; Duf26-RLK, n  =  33; Duf26-RLP, n  =  7; L-lectin-RLK, n  =  21; L-lectin-RLP, n  =  4; LysM-RLK, n  =  5; LysM-RLP, n  =  2; Malectin-RLK, n  =  13; Malectin-RLP, n  =  4. RNA-seq data analysed here were reported previously, where NTI was activated by estradiol-induced expression of AvrRps4 in A. thaliana for 4 h⁹⁴. For the expression of each class of cell-surface receptors during PTI in A. thaliana, refer to Supplementary Fig. 2.