The MAMP Peptide Patterns of Bacterial Flagellins and Their Interaction with Plant Receptors: Bioinformatic and Coevolutionary Aspects

Conserved motifs (peptide patterns) determining the elicitor properties of plant-pathogenic bacteria were identified in the amino acid sequences of the flagellins of phytopathogenic, associative, and root nodule microflora. In plant-growth-promoting rhizobacteria (PGPR), analogs of one (flg22) out of two (flg22 and flgII-28) specific peptides characteristic of pathogens were found. Instead of glycine G18, characteristic of an elicitor, tyrosine Y18 was identified in flg22 analogs of most PGPR, which prevents actuation of the phytoimmunity mechanism against PGPR. Molecular docking with the AlphaFold software package demonstrated significance of the interaction between the plant receptor FLS2 and the canonical peptide flg22 and its analogs from a plant pathogen and an Azospirillum bacterium. However, in the case of the FLS3 plant receptor, only its interactions with the canonical peptide flgII-28 and its analog from the plant pathogen were statistically significant.