Affiliations 

  • 1 Scotland's Rural College, King's Buildings, West Mains Road, EH9 3JG Edinburgh, United Kingdom. Electronic address: Maree.Brennan@univ-lorraine.fr
  • 2 Scotland's Rural College, King's Buildings, West Mains Road, EH9 3JG Edinburgh, United Kingdom
  • 3 Scotland's Rural College, King's Buildings, West Mains Road, EH9 3JG Edinburgh, United Kingdom; Green World Genetics Sdn. Bhd., 40, Jalan KIP 10, Taman Perindustrian KIP, Kepong, 52200 Kuala Lumpur, Malaysia
J Plant Physiol, 2019 Dec;243:153054.
PMID: 31648109 DOI: 10.1016/j.jplph.2019.153054

Abstract

Adhesion of the barley husk to the underlying caryopsis requires the development of a cuticular cementing layer on the caryopsis surface. Differences in adhesion quality among genotypes have previously been correlated with cementing layer composition, which is thought to influence caryopsis cuticle permeability, the hypothesised mechanism of adhesion mediation. It is not yet known whether differences in adhesion quality among genotypes are determined by changes in caryopsis cuticle permeability. We examined changes in candidate cementing layer biosynthetic and regulatory genes to investigate the genetic mechanisms behind husk adhesion quality. We used both commercially relevant UK malting cultivars and older European lines to ensure phenotypic diversity in adhesion quality. An ethylene responsive transcription factor (NUD) is required for the development of the cementing layer. To examine correlations between gene expression, cementing layer permeability and husk adhesion quality we also treated cultivars with ethephon (2-chloroethylphosphonic acid) which breaks down to ethylene, and silver thiosulphate which inhibits ethylene reception, and measured caryopsis cuticle permeability. Differential adhesion qualities among genotypes are not determined by NUD expression during development of the cementing material alone, but could result from differences in biosynthetic gene expression during cementing layer development in response to longer-term NUD expression patterns. Altered caryopsis cuticle permeability does result in altered adhesion quality, but the correlation is not consistently positive or negative. Cuticle permeability is therefore not the mechanism that determines husk adhesion quality, but is likely a consequence of the required cuticular compositional changes that determine adhesion.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.