Variation in TaSPL6-D confers salinity tolerance in bread wheat by activating TaHKT1;5-D while preserving yield-related traits

Nat Genet. 2024 Jun;56(6):1257-1269. doi: 10.1038/s41588-024-01762-2. Epub 2024 May 27.

Abstract

Na+ exclusion from above-ground tissues via the Na+-selective transporter HKT1;5 is a major salt-tolerance mechanism in crops. Using the expression genome-wide association study and yeast-one-hybrid screening, we identified TaSPL6-D, a transcriptional suppressor of TaHKT1;5-D in bread wheat. SPL6 also targeted HKT1;5 in rice and Brachypodium. A 47-bp insertion in the first exon of TaSPL6-D resulted in a truncated peptide, TaSPL6-DIn, disrupting TaHKT1;5-D repression exhibited by TaSPL6-DDel. Overexpressing TaSPL6-DDel, but not TaSPL6-DIn, led to inhibited TaHKT1;5-D expression and increased salt sensitivity. Knockout of TaSPL6-DDel in two wheat genotypes enhanced salinity tolerance, which was attenuated by a further TaHKT1;5-D knockdown. Spike development was preserved in Taspl6-dd mutants but not in Taspl6-aabbdd mutants. TaSPL6-DIn was mainly present in landraces, and molecular-assisted introduction of TaSPL6-DIn from a landrace into a leading wheat cultivar successfully improved yield on saline soils. The SPL6-HKT1;5 module offers a target for the molecular breeding of salt-tolerant crops.

MeSH terms

  • Brachypodium / genetics
  • Bread
  • Cation Transport Proteins / genetics
  • Gene Expression Regulation, Plant*
  • Genome-Wide Association Study
  • Oryza / genetics
  • Plant Proteins* / genetics
  • Plants, Genetically Modified
  • Salinity
  • Salt Tolerance* / genetics
  • Symporters / genetics
  • Symporters / metabolism
  • Triticum* / genetics

Substances

  • Plant Proteins
  • Cation Transport Proteins
  • HKT1 protein, plant
  • Symporters