| The mutation at Wx-A1, Wx-B1, and Wx-D1 alleles of hexaploid wheats 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 (RIL) through single-seed descent method. Wheat mutants carrying different null Wx alleles were identified with an improved SDS-PAGE method and the agronomic traits , grain traits, starch characteristics, dough rheological properties and noodle qualities of the eight types of Wx protein deficiency were investigated. The influence of Wx protein deficiency on starch properties and noodle qualities were studied to elucidate the relationship among Wx protein, starch properties and noodle qualities and the effects of different Wx alleles on wheat qualities. The main results were as follows.1 Identification and classification of wheat mutants at the three Wx alleles in the RIL populationA total of 228 RIL (F7) lines was obtained to investigate the presence and absence of different Wx proteins responding 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 segregation ratio of eight types was consistent with the expected segregation ratio. Theχ2 analysis showed that the null alleles at each of the three Wx loci segregated in a Mendelian fashion fitting qualitative character inheritance.2 The main agronomic characteristics of wheat mutants with the Wx protein deficiency in the RIL populationThe agronomic traits of initial blooming time, plant height, spike length, spikelet number per ear, grains number per ear and 1000-grain weight varied largely in the RIL population. The traits of plant height, spike length, spikelet number per ear and 1000-grain weight belonged to normal distribution, the variation of initial blooming time belonged to normal distribution approximately, while the plant height did not belong to normal distribution. 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 field experiment indicated that variation for grain yield traits was small among the eight types. This implies that wheat breeders can manipulate any Wx loci without a yield reduction.3 The starch properties of wheat mutants with the Wx protein deficiency in the RIL populationThe amylose content, swelling power, 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 results showed amylose decreased in the order : wild type > single null types > double null types > waxy type. Among the single null types, the amylose content decreased in the order: Wx-D1 null > Wx-A1 null > Wx-B1 null, which demonstrated that for the capacity of amylose synthesis, the Wx-D1a allele was lowest and the Wx-B1a was highest.The swelling power of the eight types with the Wx protein deficiency increased gradually when the amylose content decreased. The starch of waxy wheat has higher peak viscosity and breakdown, lower trough viscosity, final viscosity, and setback as compared with other types (P<0.05). The variation between lines in the same type of RVA parameters was different among the eight types with different Wx protein deficiencies, and the SD of types of Wx-B1 null was larger distinctly. 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. Including waxy wheat type, the amylose content was positively correlated with trough viscosity, final viscosity, setback, peak time, and pasting temperature (r=0.614~0.757, P<0.01), but negatively correlated with peak viscosity, and breakdown (r= -0.649, r= -0.795, P<0.01). Test of starch gel characteristics showed that amylose content was negatively correlated with cohesiveness and resilience (r=-0.400, r=-0.668, P<0.01), but positively correlated with hardness, adhesiveness, springiness, gumminess, and chewiness ( r=0.491~0.873, P<0.01). There was significant correlation between RVA parameters and TPA parameters. It was showed that the mutations at the Wx alleles resulted in variation of amylose content, which influenced the starch pasting properties, but also the TPA properties of starch gels.4 The rheological properties of dough of wheat mutants with the Wx protein deficiency in the RIL populationThe results of dough mixogram and extensibility of the eight types of the Wx protein deficiency indicated that the variation of dough mixogram and extensibility of the eight types of the Wx protein deficiency was big and that the mixogram and extensibility of dough had no obvious correlation with the Wx protein deficiency.5 The noodle properties of wheat mutants with the Wx protein deficiency in the RIL populationThe results showed that the noodle quality was influenced significantly by different Wx protein deficiencies. The firmness and work of shear of raw noodles of waxy wheat type (three proteins null) showed higher value than other types. After placing 48h, the firmness and work of shear of raw noodles of waxy type increased more quickly than other types. The TPA test of cooked noodles indicated that the wild type showed highest hardness, adhesiveness, gumminess, chewiness and lowest springiness, cohesiveness and resilience, while the waxy type showed lowest values. The types with one or two Wx protein subunits deficiencies showed the intermediate texture parameters. The sensory evaluation of noodles indicated that the type of Wx-B1 null showed highest noodle score with lower amylose content than wild type and other single null types. The noodles of waxy type showed poor eating quality with all parameters lower than others.Generally the noodle score increased when SP and PV of starch increased, while amylose content decreased with the Wx protein deficiencies. It was found that positive correlations among noodle score and SP and PV, negative correlations with amylose content. But the correlations was found at a certain range. The results suggested that good eating quality of noodles required appropriate physicochemical properties of starch.The multiple regression and path analysis on noodle qualities indicated the direct impact was higher than the indirect impact and the later was being. It was showed there were interreaction between quality traits.6 Grain traits and rheological characteristics of dough of wheats with different Waxy protein deficienciesThe results of grain traits of six wheat lines with different Wx protein deficiencies showed that waxy wheats had lower grain hardness and lower amylose content than Jimai 19. Partial waxy wheats showed intermediate amylose content compared to Jimai 19 and waxy wheats. The parameters of farinogram, mixogram, extensogram and stickiness of dough indicated the waxy wheats displayed anomalous water absorption properties, lower gluten strength and poor rheological property of dough, while higher extensibility, stickiness and cohesiveness of dough. The three partial waxy wheats (Sturdy, Wx-A1 null; Satanta, Wx-B1 null; IKE, Wx-A1 and Wx-B1 null) showed better dough properties than Jimai 19 and waxy wheats with higher gluten strength, lower extensibility, stickiness and cohesiveness of dough."Jisu baihuo"wheat lines with Wx-D1 null had poorer dough properties than other partial wheats.
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