2024-12-06 マックス・プランク研究所
Barley leaf sensitive (top) and resistant (bottom) to the leaf blotch fungus.
© Shaobin Zhong
米国とドイツの研究者は、大麦の葉斑病(スポットブロッチ)への感受性を高める原因が、免疫受容体「Scs6」の活性化にあることを発見しました。病原菌は「非リボソームペプチド」を放出し、Scs6を介して細胞死を誘発することで感染を広げます。Scs6は本来、病原体を排除する免疫受容体ですが、病原菌がこれを利用して大麦の防御反応を逆手に取っています。研究は1990年代の米国での感染被害をきっかけに開始され、Scs6遺伝子の変異が感受性の要因であると判明しました。耐病性のための品種改良が、別の病原体への感受性を高めるリスクがあることが示唆されました。
<関連情報>
- https://www.mpg.de/23842098/1206-zuch-pr-psl-2024-11-en-151220-x?c=2249
- https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.20289
大麦のMLA免疫受容体は真菌の非リボソームペプチドエフェクターによって活性化され病気にかかりやすくなる A barley MLA immune receptor is activated by a fungal nonribosomal peptide effector for disease susceptibility
Yueqiang Leng, Florian Kümmel, Mingxia Zhao, István Molnár, Jaroslav Doležel, Elke Logemann, Petra Köchner, Pinggen Xi, Shengming Yang, Matthew J. Moscou, Jason D. Fiedler …
New Phytologist Published: 06 December 2024
DOI:https://doi.org/10.1111/nph.20289
Summary
- The barley Mla locus contains functionally diversified genes that encode intracellular nucleotide-binding leucine-rich repeat receptors (NLRs) and confer strain-specific immunity to biotrophic and hemibiotrophic fungal pathogens.
- In this study, we isolated a barley gene Scs6, which is an allelic variant of Mla genes but confers susceptibility to the isolate ND90Pr (BsND90Pr) of the necrotrophic fungus Bipolaris sorokiniana. We generated Scs6 transgenic barley lines and showed that Scs6 is sufficient to confer susceptibility to BsND90Pr in barley genotypes naturally lacking the receptor. The Scs6-encoded NLR (SCS6) is activated by a nonribosomal peptide (NRP) effector produced by BsND90Pr to induce cell death in barley and Nicotiana benthamiana. Domain swaps between MLAs and SCS6 reveal that the SCS6 leucine-rich repeat domain is a specificity determinant for receptor activation by the NRP effector.
- Scs6 is maintained in both wild and domesticated barley populations. Our phylogenetic analysis suggests that Scs6 is a Hordeum-specific innovation.
- We infer that SCS6 is a bona fide immune receptor that is likely directly activated by the nonribosomal peptide effector of BsND90Pr for disease susceptibility in barley. Our study provides a stepping stone for the future development of synthetic NLR receptors in crops that are less vulnerable to modification by necrotrophic pathogens.
