K⁺/Na⁺ discrimination in synthetic hexaploid wheat lines: Transfer of the trait for K⁺/Na⁺ discrimination from Aegilops tauschii into a Triticum turgidum background

Abstract

Irrigation-induced salinity is a major constraint to crop production in many countries. K⁺/Na⁺ discrimination is a trait which enhances salinity tolerance in bread wheat compared to durum wheat, and is present in the wheat ancestor Aegilops tauschii. An experiment is described to assess K⁺/Na⁺ discrimination, and other traits, in a number of synthetic hexaploid wheat genotypes, produced by crossing Ae. tauschii with durum wheat. The durum parents of the synthetics were also used in the experiment, along with the CIMMYT test set of salt tolerant entries, and some synthetic hexaploid-based drought-tolerant germplasm. K⁺/Na⁺ ratios were lower in the durum parents than in the elite synthetics, confirming that the trait was present in the synthetics, and demonstrating its successful transfer from Ae. tauschii to the synthetic hexaploid wheat (2n=6x=42, AABBDD). The 14 best-performing synthetics had similar K⁺/Na⁺ ratios to the tolerant check S24. There were highly significant correlations between K⁺/Na⁺ discrimination and fresh weight within the durum parents, the elites, and the CIMMYT set. Backcrosses of some elite synthetics with the drought-susceptible hexaploid Opata failed to show the same level of discrimination as Opata.

The potential of two elite synthetics which were also tolerant to waterlogging, and one tolerant to multiple biotic stresses, for use in breeding programmes for stressed conditions was noted.