Detection of puroindoline (Pina-D1 and Pinb-D1) allelic variation in wheat landraces

Abstract

Allelic variation at the grain texture-controlling linked loci Pina-D1 and Pinb-D1 was studied among wheat landraces from the Watkins collection (pre-green revolution) using gene specific PCR based approaches. Of the 803 landraces, 593 carried the wild type alleles at these loci and were classified as soft textured. The remaining 210 genotypes were classified as hard-textured based on the presence of mutant Pin alleles known to be associated with grain hardness. Five allelic variants of Pinb-D1 were observed. Four allelic classes Pinb-D1a, Pinb-D1b, Pinb-D1c and Pinb-D1e resulted from separate single nucleotide substitutions leading to mis-sense changes, while a single base deletion at position 213 resulted in the Pinb-D1p allele exhibiting a frame shift and consequently stop codons. These five alleles occurred in six different allelic combinations with two Pina-D1 alleles (wild type and null), i.e. Pina-D1a/Pinb-D1a, Pina-D1b/Pinb-D1a, Pina-D1a/Pinb-D1b, Pina-D1a/Pina-D1c, Pina-D1a/Pinb-D1e and Pina-D1a/Pina-D1p. The alleles identified in this study provide additional resources for breeding programs for grain texture manipulations and may also have implications in microbial pathogen defence. Near-isogenic lines carrying different alleles are currently being produced to study the effect of this genetic variation on flour processing properties.