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A recombinant flagellin fragment, which includes the epitopes flg22 and flgII-28, provides a useful tool to study flagellin-triggered immunity

Serena Ciarroni, Christopher R. Clarke, Haijie Liu, Noam Eckshtain-Levi, Angelo Mazzaglia, Giorgio M. Balestra, Boris A. Vinatzer
Journal of general plant pathology 2018 v.84 no.3 pp. 169-175
Actinidia arguta, Arabidopsis thaliana, Pseudomonas syringae, amino acids, animals, epitopes, flagellin, flagellum, gene overexpression, innate immunity, kiwifruit, leaves, oxygen, plants (botany)
Plants and animals independently evolved the ability to recognize flagellin (also called FliC), the building block of the bacterial flagellum, as part of their innate immune response. While animals recognize a relatively large region of FliC, most plants recognize one or two short epitopes of FliC: flg22 and flgII-28. However, since most research in plants has focused on flg22 and flgII-28 and not the actual FliC protein, the importance of any FliC region beyond the two epitopes in plant immunity is poorly understood. Here we report cloning, overexpression, and purification of a Pseudomonas syringae FliC fragment from amino acid 1 to 143, which includes both FliC epitopes and the adjacent alpha helices. Exposing Arabidopsis thaliana leaves to FliC₁–₁₄₃ did not reveal any additional FliC recognition capabilities beyond flg22. However, while the kiwifruit species Actinidia arguta did not respond to either flg22 or flgII-28, treatment of A. arguta leaves with FliC₁–₁₄₃ triggered a significant reactive oxygen response, indicating recognition. This result suggests that in some plant species, recognition of FliC requires regions of FliC beyond the two well-known epitopes and that FliC₁–₁₄₃ represents a useful tool in the study of plant immunity.