Abstract
The AVRPPHB SUSCEPTIBLE1 (PBS1) and RESISTANCE TO PSEUDOMONAS SYRINGAE 5 (RPS5) proteins are involved in signal transduction to evoke innate plant immune response. In Arabidopsis, PBS1 is cleaved by the AvrPphB (Pseudomonas phaseolicola Avirulence protein B) protease, activating RPS5 and turning in a hypersensitive response (HR). We searched for PBS1 orthologs to trace their origin and evolution. PBS1 orthologs were found in embryophytes and in other plant taxa but with lower similarity. PBS1 phylogenetic analysis indicates high divergence, suggesting that the decoy function described for Arabidopsis PBS1 might be associated with a small fraction of orthologs. Ancestral reconstruction analysis suggests an elevated diversity in the amino acid sequence within the described motifs. All the orthologs contain the conserved PBS1 kinase subdomains, whereas the cleavage motif is present in several embryophyte orthologs but absent in most other taxa. The putative resistance recognition motifs in PBS1 orthologs are highly diverse. PBS1 cleavage site motif is exposed in some 3D structure predictions, whereas it is not in others, suggesting different modes of regulation and functions in PBS1 orthologs. Our findings suggest that PBS1 originated in the lineage that gave rise to embryophytes, with the angiosperm sequences forming a separate clade from pteridophyte proteins.
Highlights
The results presented here suggest that a PBS1-RESISTANCE TO PSEUDOMONAS SYRINGAE 5 (RPS5) system arose after the divergence of chlorophytes from terrestrial plants
The results showed five major clades (A, B, C, D, and E); clade A is subdivided into different subclades; only PBS1 orthologs of dicots were grouped into clade A, which contained AthPBS1 (A003) (Figure 6)
Pteridophytes (A498, A146, A053, and A149) and one gymnosperm (A140) were grouped in clade E (Figure 6). These results indicate that different PBS1 orthologous proteins are phylogenetically related
Summary
In general, and terrestrial plants, have coexisted with a variety of microorganisms for hundreds of millions of years through different types of interactions [1]. The colonization of terrestrial by plants was possible due to their association with symbiotic fungi [2]. The coexistence of plants and environmental microbes led to the evolution of plant systems involved in the interaction with the latter, including pathogens [3]. Such continuous interaction resulted in the increased genome complexity of both plants and their interacting microorganisms [2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
