Heterologous microProtein expression identifies LITTLE NINJA, a dominant regulator of jasmonic acid signaling

Shin-Young Hong, Bin Sun, Daniel Straub, Anko Blaakmeer, Lorenzo Mineri, Jonas Koch, Henrik Brinch-Pedersen, Inger B. Holme, Meike Burow, Hans Jørgen Lyngs Jørgensen, M. Mar Alba, Stephan Wenkel*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

20 Citations (Scopus)

Abstract

MicroProteins are small, often single-domain proteins that are sequence-related to larger, often multidomain proteins. Here, we used a combination of comparative genomics and heterologous synthetic misexpression to isolate functional cereal microProtein regulators. Our approach identified LITTLE NINJA (LNJ), a microProtein that acts as a modulator of jasmonic acid (JA) signaling. Ectopic expression of LNJ in Arabidopsis resulted in stunted plants that resembled the decuple JAZ (jazD) mutant. In fact, comparing the transcriptomes of transgenic LNJ overexpressor plants and jazD revealed a large overlap of deregulated genes, suggesting that ectopic LNJ expression altered JA signaling. Transgenic Brachypodium plants with elevated LNJ expression levels showed deregulation of JA signaling as well and displayed reduced growth and enhanced production of side shoots (tiller). This tillering effect was transferable between grass species, and overexpression of LNJ in barley and rice caused similar traits. We used a clustered regularly interspaced short palindromic repeats (CRISPR) approach and created a LNJ-like protein in Arabidopsis by deleting parts of the coding sentence of the AFP2 gene that encodes a NINJA-domain protein. These afp2-crispr mutants were also stunted in size and resembled jazD. Thus, similar genome-engineering approaches can be exploited as a future tool to create LNJ proteins and produce cereals with altered architectures.

Original languageEnglish
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number42
Pages (from-to)26197-26205
Number of pages9
ISSN0027-8424
DOIs
Publication statusPublished - 2020

Keywords

  • microProteins
  • jasmonic acid
  • branching
  • CELL ELONGATION
  • MISSING LINK
  • ARABIDOPSIS
  • TOPLESS
  • PROTEIN
  • RICE
  • DWARF
  • GENE
  • SIZE

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