GIFU UNIVERSITY
Faculty of Agriculture, 1-1 Yanagido, Gifu 501-1193 Japan.
Nobuyoshi Watanabe.
Brittle rachis, which causes spontaneous shattering of kernels, is an adaptive character of wild species. Major genes located on chromosomes 3A, 3B, and 3D determine brittle rachis. The brittle-rachis phenotype is nearly lost in domesticated wheats. Near-isogenic lines for brittle rachis have been developed for considering domestication of wheat plants. For tetraploid wheat, the brittle-rachis genes were introduced from Langdon-T. turgidum subsp. dicoccoides chromosome substitution lines, LDN(DIC 3A) and LDN(DIC 3B). The BC6 plants are growing. For hexaploid wheat, the brittle-rachis genes were derived from the Chinese endemic species, T. tibetaum and T. yunnanense, where the brittle-rachis trait is determined by a gene on chromosome 3D. These genes were incorporated into the cultivar Novosibirskaya 67. The BC4-BC6 plants are growing. They will become available soon for the experiments.
The spelt gene q is known as an alternative to the brittle-rachis gene. Near-isogenic lines for spelt also have been developed. The sources for q were T. turgidum subsps. dicoccoides, T. dicoccum, T. paleocolchicum, European T. spelta, Iranian T. spelta, T. macha, and speltoid mutants. The BC2 plants are growing. These NILs will be utilized to assess the effects of the gene for domestication of wheat.
NATIONAL AGRICULTURAL RESEARCH CENTER FOR TOHOKU REGION
Fukushima campus, Arai, Fukushima 960-2156, Japan.
Hiro Nakamura.
Summary. Protein fingerprints of common wheat endosperm were used to determine the indices of Japanese soft Udon-noodle quality. The endosperm proteins of Japanese udon wheat lines were fractionated by SDS-PAGE to determine protein-composition differences in two soil environments. The differences between the lines included differences in the composition of the endosperm with regard to a 53-kD protein band or HMW-glutenin subunit 2* and in the sensory viscoelasticity score of cooked noodles, which is related to the eating quality in Japanese udon wheats. Kanto 107 showed variation for the presence of the 53 kD and HMW-glutenin subunit 2* bands between the soil environments.
Nitrogen fertilization is a main factor affecting wheat protein and quality (Jia et al. 1996; Toyokawa et al. 1989a). Many studies have shown that the increased or decreased flour protein contents can lead to changes in wheat endosperm protein components (Scheromm et al. 1992; Zhu et al. 1999). Therefore, it would be of interest to explore the relationship between endosperm protein and udon noodle-making quality in this study. The flour protein content of wheat is usually 9-16 % of the dry weight, and world production of wheat grain protein is vast. In addition to being of great importance nutritionally, grain protein plays a fundamental part in food processing, for instance, in the manufacture of bread, biscuits, breakfast cereals, pasta, and Japanese udon-noodle products. However, most studies are applicable to the quality of wheat flour for bread, cakes, and cookies rather than for udon noodles. Improvement of end-use quality in wheat depends on a thorough understanding of the influences of environment, genotype, and their interaction (Peterson et al. 1992).
Endosperm protein composition is determined mainly by the genotype (Payne et al. 1987). However, it is largely accepted that nitrogen nutrition affects the wheat protein content and composition and directly influences the technological quality of wheat samples (Scheromm et al. 1992). Several recent reports suggest that wheat nitrogen content conditions could quantitatively affect wheat endosperm protein components (Jia et al. 1996; Zhu et al. 1999). The quantitative and qualitative differences in endosperm-protein composition observed upon exposure of the same genotype to different field conditions and wheat flour nitrogen contents under similar climatic conditions have not been previously described. Udon-making quality from paddy field is not much better than that of udon wheat grown in an upland field due to a lower protein content of wheat grains in Japan (Yamashita 1994). Recently, this has been an important problem in udon wheat production in Japan. Due to paddy-rice overproduction in Japan, udon wheat has been grown in paddy fields instead of cultivating paddy rice. Therefore, improving the quality of udon wheat from paddy fields has been a most important research component of wheat breeding in Japan.
Statistically significant correlations were found in the present study for the Japanese udon wheat 53-kD protein band, HMW-glutenin subunit 2*, flour-protein content, sensory viscoelasticity score of cooked soft salted-noodles, flour-amylose content, and different field types. Significant differences in the band pattern of endosperm proteins from various genotypes between upland and paddy fields were observed in this study. All the differences observed in this research were demonstrated by simple 1-dimensional SDS-PAGE. Therefore, most protein effects (quantitative and qualitative) presented on the gel are based on differences in the HMW-glutenin subunit 2* and 53-kD protein band (LMW-glutenin or gliadin).
In the present study, the nitrogen deficiency of wheat in the paddy fields for the first two wheat-growing seasons may have prevented the synthesis in only Kanto 107 of the 53-kD protein band and instead produced the HMW-glutenin subunit 2* protein band and may explain the low-protein content in the first and second growing seasons, when there was an absence of the 53-kD protein band and an accompanying presence of HMW-glutenin subunit 2* for Kanto 107. However, further work using a greater number of pure varieties or lines with different genetic backgrounds is needed to confirm these results. Climatic conditions between seasons could not explain the observed differences in protein composition, because all plants of each genotype were exposed to the same amount of water and the same temperature during the wheat-growing season in the same field, and the 53-kD protein band and HMW-glutenin subunit 2* of Kankei lines or Norin 61 were stable. Although the nitrogen availability caused variations in endosperm protein components by affecting the nitrogen nutrient supply, genotype was a more important factor in determining the final protein composition. The quantitative and qualitative differences in endosperm protein composition were observed under field conditions of wheat nitrogen deficiency. This work also demonstrated that under nitrogen-deficient field conditions, the use of endosperm-protein fingerprints from naturally growing wheat plants can be misleading as a breeding tool. Cereals grown in nitrogen-deficient soils that are different from those in which they were bred could produce grains with different amounts of each gluten component (Scherommet al. 1992; Jia et al. 1996; Zhu et al. 1999), which would have implications if the affected protein is a determinant of flour quality. Caution should be exercised when identifying the field source of seeds used for wheat breeding, especially from genetic resources with high-protein content. However, the most important texture of udon-noodle acceptability is the sensory viscoelasticity score related to eating-quality of cooked noodles (National Food Research Institute 1984; Nakamura 2001).
From these studies, we concluded that the primary protein 53-kD band of endosperm protein appeared to be most responsible for the desirable viscoelastic texture of cooked udon-noodle. In contrast, the primary protein HMW-glutenin subunit 2* of endosperm protein appeared to be most responsible for reduced viscoelastic texture of cooked udon-noodle. Kanto 107 and the four Kankei lines possessed the 53-kD protein band related to good sensory viscoelasticity score and eating quality of cooked noodles. These two protein bands of Kanto 107 were sensitive to different protein contents between different field conditions, but this sensitivity was not evident in Norin 61 and the Kankei lines. No relatively variability in protein components such as the 53-kD protein band and HMW-glutenin subunit 2* were observed, and their sensory viscoelasticity scores of cooked noodle were likewise stable.
Therefore, it is of interest that Norin 61 do not have the 53-kD protein band that is correlated to high sensory viscoelasticity in cooked udon noodles. Jia et al. (1996) reported that accumulation of gliadins becomes more important than that of glutenin, and albumins and globulins are less represented as the flour protein increases. The protein content may not only affect the quantitative, but also qualitative, characters.
In wheat breeding programs aimed at changing the endosperm-protein band pattern, the fingerprint has been considered a reliable wheat breeding tool. The information may also be of interest to plant breeders, because breeders are now taking endosperm-protein composition into account when choosing patterns for intended crosses to produce good udon wheat lines. The apparent importance of amylose and the influence of amylose/amylopectin ratios on udon quality has been studied (Takada 1987; Toyokawa et al. 1989). We know that a low amylose content (a high amylopectin content) is correlated with good udon-noodle viscoelasticity scores of 21.0-25.0 (full score) and is correlated with high udon-noodle making quality in Japan. Starches of varied amylose/amylopectin ratios have been selected and incorporated into Japanese udon-wheat breeding programs. In our study, flour amylose content influenced the sensory viscoelasticity score of cooled noodles; however, the two primary endosperm protein bands had a greater effect on the sensory viscoelasticity score of cooked noodles. In the present study, amylose content does not seem to play the most major role in increasingly the sensory viscoelasticity score of cooled noodles. However, it is probable that the 53-kD protein band and HMW-glutenin subunit 2* strongly affect to the sensory viscoelasticity scores of udon noodles.
Nagao et al. (1977) reported that selected Australian wheats and American soft white and white club wheats showed favorable characteristics for Japanese udon-type noodles and also that Australian standard white is superior to Japanese wheat in udon-making quality (Takada 1987). This approach to the selection of early-generation udon wheat lines in the Japanese udon-wheat breeding program is very effective, particularly because the procedure is simple, and experimental equipment can be obtained at reasonable price. Good udon wheat lines, such as Kanto 107, may give poor udon-noodle making quality when used in nutrient-deficient conditions.
Acknowledgments.
The author wishes to thank Mrs. Shinko Kawakami for her assistance
with this research work. Thanks are due to National Agriculture
Research Center for providing wheat samples.
References.