**1. Introduction**

[58] Tsurumaru H., Yamakawa T., Tanaka M., Sakai M. The Efficient Strategy of Plasmid Rescue from Tn*5* Mutants Derived from *Bradyrhizobium japonicum* Is-1, Based on Whole Genome Sequence Information of Strain USDA110. Journal of the Faculty of

A Comprehensive Survey of International Soybean Research - Genetics, Physiology, Agronomy and Nitrogen

[59] Hardarson G., Golbs M., Danso SKA. Nitrogen Fixation in Soybeans (*Glycine max* L. Merrill) as Affected by Nodulation Patterns. Soil Biology and Biochemistry 1989:

[60] Lohrke SM., Madrzak CJ., Hur H., Judd AK., Orf JH., Sadowsky MJ. Inoculum Densi‐ ty-Dependent Restriction of Nodulation in the Soybean*-Bradyrhizobium japonicum*

[61] Yamakawa T., Tanaka M., Sakai M., Sarr PS. Genetic Grouping of *Bradyrhizobium* Strains Compatible with Soybean (*Glycine max* L. Merr.) Harboring *Rj-*gene by AFLPfingerprinting Analysis. Journal of the Faculty of Agriculture, Kyushu University

[62] Wei X., Bauer WD. Tn*5*-Induced and Spontaneous Switching of *Sinorhizobium meliloti* to Faster-Swarming Behavior. Applied and Environmental Microbiology 1999: 65(3)

[63] Rosen BP., Bhattacharjee H., Shi W. Mechanisms of Metalloregulation of an Anion-Translocating ATPase. Journal of Bioenergetics and Biomembranes 1995: 27(1) 85–91.

[64] Ulusu NN., Tezcan EF. Cold Shock Proteins. Turkish Journal of Medical Sciences

[65] Judd AK., Sadowsky MJ., Bhagwat AA., Cregan PB., Liu RL. Isolation of a *Bradyrhi‐ zobium japonicum* Serogroup 123 Mutant Which Has an Extended Host Range for Nodulation-Restricting Soybean Genotypes. FEMS Microbiology Letters 1993: 106(2)

[66] Fukushima Y., Yamakawa, T. Effect of Difference of Inoculation Method and Inocu‐ lum Density of *Bradyrhizobium japonicum* USDA110 on Production of Soybean (*Gly‐ cine max* L. Merr.), Science bulletin of the Faculty of Agriculture, Kyushu University

[67] Fehr WR., Cavines, CE., Burmood DT., Pennington JS. Stage of Development De‐ scriptions for Soybeans, *Glycine max* (L) Merrill. Crop Science 1971: 11(6) 929-931.

[68] Smith RS. Legume Inoculant Formulation and Application. Canadian Journal of Mi‐

2006: 61(2) 171-176. (in Japanese with English summary)

Agriculture, Kyushu University 2008: 53(1) 27-31.

Symbiosis. Symbiosis 2000: 29(1) 59-70.

21(6) 783-787.

Relationships

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2011: 56(2) 223-229.

2001: 31(4), 283–290.

crobiology 1992: 38(6) 485-492.

1228–1235.

205–210.

The world population is consistently increasing, and it is over 7 billion in 2012, while the land area for agricultural use is limited. Therefore, the increase in crop production per area is very important. Soybean (*Glycine max* (L.) Merr.) originates from East Asia, and soybean seed is one of the most important protein sources for human and livestock all over the world. Annual production of soybean (262 M (million) t in 2010) is the fourth of the major grain crops, after maize (844 M t), paddy rice (672 M t) and wheat (650 M t) [1]. In the whole world, over 85% of soybean is used for oil and the residue is used for animal feed. Annual soybean seed production has been steadily increasing for recent decades (91 M t in 1980, 109 M t in 1990, 161 M t in 2000, 262 M t in 2010) [1]. The cultivation area of soybean is 102 M ha in 2010. Major soybean production countries (annual production in 2010) are USA (90.6 M t), Brazil (68.5 M t), Argentina (52.7 M t), China (15.1 M t), and India (9.8 M t) in this sequence. Soybean production in Japan in 2010 was only 223,000t and it accounted for 5% of the total consumption in Japan. The world average seed yield is 2.56 t ha-1 in 2010, and is higher in the USA (2.92 t ha-1), Brazil (2.94 t ha-1), and Argentina (2.90 t ha-1) compared with China (1.77 t ha-1), Japan (1.62 t ha-1) and India (1.07 t ha-1) and other countries.

The nutrient composition of soybean seeds (per 100 g) produced in Japan is as follows [2]; energy 417 kcal (1,745 kJ), water 12.5g, protein 35.3g, lipids 19.0g, carbohydrate 28.2g, min‐ erals 5g. The composition is quite different from the other grain crop seeds, such as "Paddy rice"; energy 350 kcal (1,464 kJ), water 15.5g, protein 6.8g, lipids 2.7g, carbohydrate 73.8g, minerals 1.2g, "Wheat"; energy 337 kcal (1,410 kJ), water 12.5g, protein 10.6g, lipids 3.1g, carbohydrate 72.2g, minerals 1.6g, and "Corn"; energy 350 kcal (1,464 kJ), water 14.5g, pro‐ tein 8.6g, lipids 5.0g, carbohydrate 70.6g, minerals 1.3g. The protein concentration in soy‐

bean seeds is very high about 4-5 times higher than that of rice, wheat and corn, but carbohydrate concentration is lower.

The storage protein of soybean seeds mainly consists of glycinin and β-conglycinin. The βconglycinin is comprised of three subunits, designated as α', α, and β-subunits. The β-subu‐ nit of β-conglycinin is especially low in sulfur amino acids, containing only one cysteine and no methionine residue in its mature form. Soybean seeds contain a large amount of lipids (20%), and about 90% is unsaturated fatty acid (linoleic acid 51-57%, oleic acid 32-36% and linolenic acid 2-10%) and 10% is saturated fatty acid (palmitic acid 4-7%, stearic acid 4-7%) [3]. Linoleic acid and linolenic acid are essential lipids, which cannot be synthesized by our‐ selves. Although soybean seeds contain about 28% carbohydrates, most of them are struc‐ tural carbon like cell walls and oligosaccharides (sucrose 5%, stachyose 4%, raffinose 1%). Starch is tentatively accumulated in young immature soybean seed, however, it decreases and converts to lipid and protein at maturity. Soybean seeds contain relatively a high amount of minerals (5%) compared with cereal seeds (about 1%). Soybean seeds contain abundant potassium (1,900 mg), calcium (240 mg), magnesium (220 mg), phosphorous (220 mg), iron (9.4 mg), zinc (3.2 mg) per 100g seeds. Soybean seeds contain vitamins, both lipid soluble vitamins (Vitamin E (1.8 mg)) and water soluble vitamins (V B1 (0.83 mg) and V B2 (0.30 mg)). Soybean seeds contain isoflavonoids, daidzein and genistein. These isoflavonoids are expected to play a role as a female hormone or to decrease fat in blood.
