Effect of wx genes on amylose content, physicochemical properties of wheat starch, and the suitability of waxy genotype for producing Chinese crisp sticks

• wx gene showed significant effects on amylose content and most other traits studied.
• No morphological differences of starch granules were observed among all genotypes.
• Waxy genotype showed significant better crisp stick quality than non-waxy genotypes.
• This indicated the potential value of waxy wheat in producing traditional products.

The effect of wx genes on amylose content, physicochemical properties of wheat starches, and the quality of Chinese crisp stick were investigated using near-isogenic lines (NILs) with null wx alleles in Yangmai 17 and Yangmai 01-2 backgrounds. wx genes showed significant effects on amylose content and other traits. The triple-null genotype had the lowest amylose content among eight genotypes, followed by double-null, single-null, and wild-type genotypes. The triple-null also showed lower flour yield, higher percentage of type B-granules on a volume basis and higher crystallinity than non-waxy genotypes, and showed significant differences in all pasting and thermal transition parameters compared to non-waxy genotypes, except for degree of retrogradation at day 14. For the quality of Chinese crisp stick, the hardness, crispness, fracturability, and specific volume of waxy genotype were 3.91 kg, 11.0, 1.85 mm and 104.4 ml, whereas the corresponding ranges for non-waxy genotypes were 5.39–5.70 kg, 0.5–0.9, 0.69–0.86 mm and 49.5–57.6 ml, respectively, in Yangmai 17 background. This indicates that waxy genotypes showed significantly better crisp stick quality than non-waxy genotypes. A similar trend was also observed in Yangmai 01-2 background. This indicated the potential utilization of waxy wheat for producing traditional products.