Poster: Plant Pathogen/Symbiont Interactions
Abs #
717: Biological Functions of FLS2 and Bacterial Flagellin in the Plant Immune System
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Presenter: |
Dunning, Francis M, fmdunning@wisc.edu |
Authors | Dunning, Francis M (A) Pfund, Christine (A) Tans-Kersten, Julie (A) Allen, Caitilyn (A) Bent, Andrew F (A) | | Affiliations: |
(A): University of Wisconisin- Madison
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In order to survive, plants must recognize pathogen attack and activate defenses to limit pathogen growth. Plant resistance (R) gene products allow recognition of pathogen elicitors and confer strong resistance. The majority of known R genes encode a leucine rich repeat (LRR) domain, within which mutations can significantly alter pathogen recognition. We are studying the determinants of specificity between the weak R gene FLS2, a LRR receptor-like kinase, and bacterial flagellin. Previous studies by Boller and colleagues have shown that flg22, a 22 amino acid peptide based on the conserved N-terminal domain of bacterial flagellin, and crude flagellin extracts from many bacteria, activate FLS2-mediated defense responses in Arabidopsis (Gomez-Gomez 2002 Trends Plant Sci 7:251). In our studies with Arabidopsis, crude flagellin extracts from 14 Xanthomonas campestris pv. campestris (Xcc) strains exhibited a wide range of defense elicitation activity. Sequence comparisons of the flg22 regions from these Xcc strains have indicated positions that may serve as determinants of specificity for the FLS2/flagellin interaction. We are examining the correlation between flagellin sequence and the virulence of Xcc strains on Arabidopsis. We are also studying the role of flagellin as a general elicitor of plant defenses using Ralstonia solanacearum mutants. Crude flagellin extracts from strains lacking flagella still elicit strong plant responses, indicating another elicitor besides flagellin is present. This second elicitor, a protein >8 kD, is apparently an additional pathogen-associated molecular pattern recognized by Arabidopsis. Future studies will further examine the role of FLS2 and flagellin in innate immunity and may highlight FLS2 LRR residues that alter pathogen specificity.
