Abstract:

The mutation at Wx-A1, Wx-B1, and Wx-D1 alleles may cause lack of Wx-A1, Wx-B1, and Wx-D1 proteins, and influence obviously the wheat quality. We use a normal cultivar Gaocheng 8901 (carrying three Wx genes) and Waxy Wheat 1 (null at the three Wx alleles) to develop a population of recombinant inbred lines (RILs) through single-seed descent method. A total of 228 RIL (F₇) lines was obtained to study the agronomic traits and starch characteristics responsing to Wx allele mutation, among which 34 of wild types, 26 of Wx-A1 null, 32 of Wx-B1 null, 30 of Wx-D1 null, 28 of Wx-A1 and Wx-B1 null, 20 of Wx-A1 and Wx-D1 null, 28 of Wx-B1 and Wx-D1 null, and 16 of waxy lines with the three null alleles were examined by improved sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The null allele at each Wx locus fits Mendelian segregation by chi-square test. Field experiments did not show significant differences (P>0.05) in the traits of initial blooming stage, plant height, and grain number per ear among the eight types, but the Wx-A1 null type was significantly lower (P<0.05) than other seven types in the traits of spike length, spikelet number per ear, and 1000-grain weight, while there were no significant differences among the seven types. The amylose content, starch pasting characteristics, and TPA characteristics of starch gels were all influenced significantly by different Wx protein deficiencies. The highest amylose content appeared in the wild type (20.8%), and the lowest in the waxy type (1.1%). The starch in waxy wheat has higher peak viscosity and breakdown, lower trough viscosity, final viscosity, and setback as compared with other types (P<0.05). With the decrease of amylose content, the hardness, adhesiveness, springiness, gumminess and chewiness of starch gels decreased, while cohesiveness, and resilience increased significantly in the eight types. The amylose content was positively correlated with trough viscosity, final viscosity, setback, peak time, and pasting temperature (r=0.892–0.965, P<0.01), but negatively correlated with peak viscosity, and breakdown (r=－0.892, r=－0.945, P<0.01). Test of starch gel characteristics showed that amylose content was negatively correlated with cohesiveness, and resilience (r=－0.928, r=－0.829, P<0.01), but positively correlated with hardness, adhesiveness, springiness, gumminess, and chewiness ( r=0.869~0.979, P<0.01).

Key words: Waxy allele, Recombinant inbred line, Starch property, Wheat (Triticum aestivum L.)