GIFU UNIVERSITY - FACULTY OF AGRICULTURE
1 - 1 Yanagido, Gifu 501 - 1193, Japan.
Nobuyoshi Watanabe.
Chinese wheat landrace, Xinjiang rice wheat, is characterized by long glumes that look similar to those of T. turgidum subsp. polonicum. Xinjiang rice wheat was found in the agricultural areas in the west part of the Talimu basin, Xinjiang, China, in 1948. Xinjiang rice wheat was thought be a mutated form of T. polonicum, however, its chromosome number is 2n = 42 and was named T. petropavlovskyi Udacz. et Migusch. The gene for long glume (tentatively P3) from T. petropavlovsky was introduced into the spring durum wheat LD222. The gene for long glume in T. petropavlovskyi is located on chromosome 7A. We propose that T. petropavlovsky originated as an interspecific hybridization between T. aestivum and T. polonicum.
A catalog of NILs of the durum wheat LD222 is now available at the web address: http://www.gifuñu.ac.jp/~watnb/Catalogue.htm
TOHOKU NATIONAL AGRICULTURAL EXPERIMENT STATION
Ministry of Agriculture, Forestry, and Fisheries, Morioka, Iwate 020-0198, Japan.
Hiro Nakamura and Hiroshi Fujimaki (Tokyo University of Agriculture, Tokyo 156-8502, Japan).
In order to strengthen the international competitiveness of domestically produced wheat, improvement in wheat quality to fit to demand of the Japanese consumer is urgently needed. For this purpose, characterizing the genetic resources and quality of Japanese wheat varieties is essential. Wheat processing quality is correlated highly with seed storage proteins. The HMW-glutenin subunit composition is a principal component of wheat seed storage proteins. Our objective was to investigate the composition of the HMW-glutenin subunits and to collect useful information for improving the quality of Japanese hexaploid wheats.
The HMW-glutenin subunits of the improved Japanese varieties, Japanese landraces, and Chinese varieties were isolated by SDS-PAGE. The highest molecular weight subunit, named 145 kDa, frequently appeared in the improved varieties, the landraces, and characterized Japanese wheats. The N-terminal amino-acid sequence of the glutenin 145-kDa subunit was determined by a gas-phase sequencer. Examination of the amino-acid sequence and electrophoresis mobility revealed that this subunit was identical to that of the 2.2 band reported by Payne et al. (1983). Genetic analyses of two crosses between varieties with and without the 145-kDa subunit indicated that the expression of this glutenin subunit was controlled by a single dominant allele (Glu-D1f) located on chromosome 1D. The frequency of this allele was greater than 35 % in the improved Japanese varieties, contrasting with an amount less than 25 % in the Japanese landraces. Only a few of the Chinese varieties contain this subunit. Genealogical studies showed that the 145-kDa subunit not only was in the cultivar Nisikaze-komugi, selected in the Kyushu district (southern Japan) and appeared frequently in its pedigree, but was absent in Horoshiri-komugi, a cultivar selected in the Hokkaido district (northern Japan) and was found in only a few remote ancestors.
A noticeable geographical distribution was observed in the frequency of the allele expressing the 145-kDa subunit. We investigated the relationship between the occurrence of the subunit and winter habit or flour hardness. The environment for wheat growing in Japan is diverse because the long expanse of the islands from north to south. The improved Japanese varieties and the Japanese landraces have different types of winter habit. A close correlation was observed between the degree of winter habit and the occurrence of the 145-kDa subunit. The more improved varieties had a weaker winter habit and the 145-kDa subunit. The 145-kDa subunit was not found in varieties with a strong winter habit.
Wheat flour hardness is reported to be closely related with quality. The relationship between flour hardiness and the occurrence of the 145-kDa subunit was examined to determine if soft-flour varieties had the 145-kDa subunit more frequently than the hard-flour varieties. We concluded that the geographical distribution observed in Japanese varieties with the 145-kDa subunit is considered to be caused by natural selection for winter habit and/or by artificial selection for flour hardness. A cultivated hexaploid wheat is known to have originated in the Middle and Near East and reached the Far East, including Japan, traveling along the Silk Road. During this long journey, adaptation to diverse local environments and genetic diversity seems to have been considerably reduced in hexaploid wheats. The frequent occurrence of the glutenin 145-kDa subunit could be a part of the story. Natural or artificial selection is thought to have been narrowed the genetic diversity of Japanese wheat. To improve hexaploid wheat quality, broadening the genetic diversity of domestic wheat in Japan by inducing new useful mutations such as glutinousness or by exploiting the new wheat genetic resources is essential.