PLoS Genetics (Jul 2019)

RPW8/HR repeats control NLR activation in Arabidopsis thaliana.

  • Cristina A Barragan,
  • Rui Wu,
  • Sang-Tae Kim,
  • Wanyan Xi,
  • Anette Habring,
  • Jörg Hagmann,
  • Anna-Lena Van de Weyer,
  • Maricris Zaidem,
  • William Wing Ho Ho,
  • George Wang,
  • Ilja Bezrukov,
  • Detlef Weigel,
  • Eunyoung Chae

DOI
https://doi.org/10.1371/journal.pgen.1008313
Journal volume & issue
Vol. 15, no. 7
p. e1008313

Abstract

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In many plant species, conflicts between divergent elements of the immune system, especially nucleotide-binding oligomerization domain-like receptors (NLR), can lead to hybrid necrosis. Here, we report deleterious allele-specific interactions between an NLR and a non-NLR gene cluster, resulting in not one, but multiple hybrid necrosis cases in Arabidopsis thaliana. The NLR cluster is RESISTANCE TO PERONOSPORA PARASITICA 7 (RPP7), which can confer strain-specific resistance to oomycetes. The non-NLR cluster is RESISTANCE TO POWDERY MILDEW 8 (RPW8) / HOMOLOG OF RPW8 (HR), which can confer broad-spectrum resistance to both fungi and oomycetes. RPW8/HR proteins contain at the N-terminus a potential transmembrane domain, followed by a specific coiled-coil (CC) domain that is similar to a domain found in pore-forming toxins MLKL and HET-S from mammals and fungi. C-terminal to the CC domain is a variable number of 21- or 14-amino acid repeats, reminiscent of regulatory 21-amino acid repeats in fungal HET-S. The number of repeats in different RPW8/HR proteins along with the sequence of a short C-terminal tail predicts their ability to activate immunity in combination with specific RPP7 partners. Whether a larger or smaller number of repeats is more dangerous depends on the specific RPW8/HR autoimmune risk variant.