Premium
Multiple downy mildew effectors target the stress‐related NAC transcription factor Ls NAC 069 in lettuce
Author(s) -
Meisrimler ClaudiaNicole,
Pelgrom Alexandra J. E.,
Oud Bart,
Out Suzan,
Van den Ackerveken Guido
Publication year - 2019
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.14383
Subject(s) - effector , biology , two hybrid screening , arabidopsis , microbiology and biotechnology , genetics , gene , mutant
Summary To cause disease in lettuce, the biotrophic oomycete Bremia lactucae secretes potential Rx LR effector proteins. Here we report the discovery of an effector‐target hub consisting of four B. lactucae effectors and one lettuce protein target by a yeast‐two‐hybrid (Y2H) screening. Interaction of the lettuce tail‐anchored NAC transcription factor, Ls NAC 069, with B. lactucae effectors does not require the N‐terminal NAC domain but depends on the C‐terminal region including the transmembrane domain. Furthermore, in Y2H experiments, B. lactucae effectors interact with Arabidopsis and potato tail‐anchored NAC s, suggesting that they are conserved effector targets. Transient expression of Rx LR effector proteins BLR 05 and BLR 09 and their target Ls NAC 069 in planta revealed a predominant localization to the endoplasmic reticulum. Phytophthora capsici culture filtrate and polyethylene glycol treatment induced relocalization to the nucleus of a stabilized Ls NAC 069 protein, lacking the NAC ‐domain (Ls NAC 069 Δ NAC ). Relocalization was significantly reduced in the presence of the Ser/Cys‐protease inhibitor TPCK indicating proteolytic cleavage of Ls NAC 069 allows for relocalization. Co‐expression of effectors with Ls NAC 069 Δ NAC reduced its nuclear accumulation. Surprisingly, Ls NAC 069 silenced lettuce lines had decreased Ls NAC 069 transcript levels but did not show significantly altered susceptibility to B. lactucae . In contrast, Ls NAC 069 silencing increased resistance to Pseudomonas cichorii bacteria and reduced wilting effects under moderate drought stress, indicating a broad role of Ls NAC 069 in abiotic and biotic stress responses.