Increased wheat (Triticum aestivum L.) grain hardness conferred by novel puroindoline haplotypes and its effects on end use quality

Abstract

The Puroindoline genes (Pina and Pinb) together comprise the wheat (Triticum aestivum L.) Hardness locus (Ha) located on chromosome 5D and control grain texture. While hard wheats contain a mutation in either Pina or Pinb, there is no puroindoline allelic diversity among soft hexaploid wheats as all tested soft wheats carry the Pina-D1a/Pinb-D1a alleles. However, abundant Pina and Pinb allelic variation exists within synthetic hexaploid wheats created using novel D genome donors. A previous study indicated that the Pina-D1c/Pinb-D1h haplotype conferred a 10 unit decrease in hardness compared to the Pina-D1a/Pinb-D1a Ha haplotype. Here we tested the effects of four novel Ha locus haplotypes (Pina-D1c/Pinb-D1h, Pina-D1e/Pinb-D1i, Pina-D1a/Pinb-D1i, and Pina-D1j/Pinb-D1i) from synthetic wheats by crossing Pina-D1c/Pinb-D1h into the soft white spring wheat, 'Alpowa' and all four haplotypes into the soft white spring wheat, 'Vanna'. PINAa/PINBh, PINAc/PINBh, and PINAj/PINBh did not affect protein levels and Pina-D1c/Pinb-D1h did not affect transcript levels found in the seed. Pina-D1c/Pinb-D1h was found to increase grain hardness relative to the wild type Ha locus by an average of 6.5 units for all populations, Pina-D1e/Pinb-D1i by 5.6 units, Pina-D1a/Pinb-D1i by 12.6 units, and Pina-D1j/Pinb-D1i by 3.8 units. In examining the effects of one of these novel loci, Pina-D1c/Pinb-D1h, on end use quality, it is evident that the synthetic Ha haplotype can decrease sugar snap cookie diameter and increase flour particle size. Other baking quality traits appear to be unaffected by the Pina-D1ac/Pinb-D1h Ha haplotype. These findings may be beneficial to breeders looking to improve the baking qualities of high yielding soft wheat varieties.