A short internodes (SHI) family transcription factor gene regulates awn elongation and pistil morphology in barley

Takahisa Yuo, Yuko Yamashita, Hiroyuki Kanamori, Takashi Matsumoto, Udda Lundqvist, Kazuhiro Sato, Masahiko Ichii, Stephen A. Jobling, Shin Taketa

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)


The awn, an apical extension from the lemma of the spikelet, plays important roles in seed dispersal, burial, and photosynthesis. Barley typically has long awns, but short-awn variants exist. The short awn 2 (lks2) gene, which produces awns about 50% shorter than normal, is a natural variant that is restricted to Eastern Asia. Positional cloning revealed that Lks2 encodes a SHI-family transcription factor. Allelism tests showed that lks2 is allelic to unbranched style 4 (ubs4) and breviaristatum-d (ari-d), for which the phenotypes are very short awn and sparse stigma hairs. The gene identity was validated by 25 mutant alleles with lesions in the Lks2 gene. Of these, 17 affected either or both conserved regions: the zinc-binding RING-finger motif and the IGGH domain. Lks2 is highly expressed in awns and pistils. Histological observations of longitudinal awn sections showed that the lks2 short-awn phenotype resulted from reduced cell number. Natural variants of lks2 were classified into three types, but all shared a single-nucleotide polymorphism (SNP) that causes a proline-to-leucine change at position 245 in the IGGH domain. All three lks2 natural variants were regarded as weak alleles because their awn and pistil phenotypes are mild compared with those of the 25 mutant alleles. Natural variants of lks2 found in the east of China and the Himalayas had considerably different sequences in the regions flanking the critical SNP, suggesting independent origins. The available results suggest that the lks2 allele might have a selective advantage in the adaptation of barley to high-precipitation areas of Eastern Asia.

Original languageEnglish
Pages (from-to)5223-5232
Number of pages10
JournalJournal of experimental botany
Issue number14
Publication statusPublished - Sep 2012


  • Hordeum vulgare L.
  • IGGH domain
  • RING finger
  • stigma
  • varietal difference

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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