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Rpa1 mediates an immune response to avrRpm1 Psa and confers resistance against Pseudomonas syringae pv. actinidiae
Author(s) -
Yoon Minsoo,
Rikkerink Erik H.A.
Publication year - 2020
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14654
Subject(s) - pseudomonas syringae , effector , nicotiana benthamiana , biology , gene silencing , microbiology and biotechnology , immune system , pathogen , gene , genetics
Summary The type three effector AvrRpm1 Pma from Pseudomonas syringae pv. maculicola (Pma) triggers an RPM1‐mediated immune response linked to phosphorylation of RIN4 (RPM1‐interacting protein 4) in Arabidopsis. However, the effector–resistance (R) gene interaction is not well established with different AvrRpm1 effectors from other pathovars. We investigated the AvrRpm1‐triggered immune responses in Nicotiana species and isolated Rpa1 ( R esistance to P seudomonas syringae pv. a ctinidiae 1) via a reverse genetic screen in Nicotiana tabacum . Transient expression and gene silencing were performed in combination with co‐immunoprecipitation and growth assays to investigate the specificity of interactions that lead to inhibition of pathogen growth. Two closely related AvrRpm1 effectors derived from Pseudomonas syringae pv. actinidiae biovar 3 (AvrRpm1 Psa ) and Pseudomonas syringae pv. syringae strain B728a (AvrRpm1 Psy ) trigger immune responses mediated by RPA1, a nucleotide‐binding leucine‐rich repeat protein with an N‐terminal coiled‐coil domain. In a display of contrasting specificities, RPA1 does not respond to AvrRpm1 Pma , and correspondingly AvrRpm1 Psa and AvrRpm1 Psy do not trigger the RPM1‐mediated response, demonstrating that separate R genes mediate specific immune responses to different AvrRpm1 effectors. AvrRpm1 Psa co‐immunoprecipitates with RPA1, and both proteins co‐immunoprecipitate with RIN4. In contrast with RPM1, however, RPA1 was not activated by the phosphomimic RIN4 T166D and silencing of RIN4 did not affect the RPA1 activity. Delivery of AvrRpm1 Psa by Pseudomonas syringae pv. tomato (Pto) in combination with transient expression of Rpa1 resulted in inhibition of the pathogen growth in N. benthamiana . Psa growth was also inhibited by RPA1 in N. tabacum .