Interaction between row-type genes in barley controls meristem determinacy and reveals novel routes to improved grain

Monika Zwirek, Robbie Waugh, Sarah M. McKim (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)
166 Downloads (Pure)


Hordeum species develop a central spikelet flanked by two lateral spikelets at each inflorescence node. In ‘two-rowed’ spikes, the central spikelet alone is fertile and sets grain, while in ‘six-rowed’ spikes, lateral spikelets can also produce grain. Induced loss-of-function alleles of any of five Six-rowed spike (VRS) genes (VRS1-5) cause complete to intermediate gains of lateral spikelet fertility. Current six-row cultivars contain natural defective vrs1 and vrs5 alleles. Little information is known about VRS mechanism(s). We used comparative developmental, expression and genetic analyses on single and double vrs mutants to learn more about how VRS genes control development and assess their agronomic potential. We show that all VRS genes repress fertility at carpel and awn emergence in developing lateral spikelets. VRS4, VRS3 and VRS5 work through VRS1 to suppress fertility, probably by inducing VRS1 expression. Pairing vrs3, vrs4 or vrs5 alleles increased lateral spikelet fertility, despite the presence of a functional VRS1 allele. The vrs3 allele caused loss of spikelet identity and determinacy, improved grain homogeneity and increased tillering in a vrs4 background, while with vrs5, decreased tiller number and increased grain weight. Interactions amongst VRS genes control spikelet infertility, determinacy and outgrowth, and novel routes to improving six-row grain.

Original languageEnglish
Pages (from-to)1950-1965
Number of pages38
JournalNew Phytologist
Issue number4
Early online date19 Oct 2018
Publication statusPublished - 7 Feb 2019


  • barley (Hordeum vulgare)
  • branching
  • grain number
  • meristem
  • spikelet fertility
  • yield potential

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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