History of Soy

On The Domestication of the Soybean

Page 3

The genus Glycine has an Old World distribution (Table I). The perennial species in the subgenus Glycine occur in Australia, Micronesia, Melanesia, Philippines, Taiwan and Southeast China (14, 37, 40, 49, 69). All species in the subgenus Glycine examined have chromosome complements of 2n = 40 or 2n = 80 (24, 56, 65, 88, 89, 109). Chromosone numbers have not been reported for G. canescens, G. latrobeana, or G. clandestinavar sericea.Palmer and Hadley (83) were successful in making interspecific hybrids within the subgenus Glycine. They crossed an induced autotetraploid 4X G. tomentella (2n = 80) with G. tabacina (2n = 80). The F1 hybrids were morphologically intermediate between the parents. However, the investigators were unsuccessful in their attempts to cross either G. tomentella or G. tabacina with G. max on the diploid or tetraploid level.

Plants of G. wightii subgenus Bracteata (Table I) are climbing vinelike perennials which have shown promise as a pasture legume in the tropics and sub-tropics (4, 8, 59, 78, 124). The species is indigenous to Africa and Southeastern Asia (40). Glycine wightii is commonly called perennial soybean or Rhodesian kudzu vine (68). In South Africa the plant is referred to as olieboontjie, while in Uganda it is called agaba, edila, ekibowabowa, kaihabukuru, and omwetsindagye (63, 100). Williamson (127) reports that in Malawi, the leaves of G. wightii are frequently cooked as a side dish.

There is extensive literature on chromosome counts of G. wightii (8, 24, 25, 65, 66, 75, 89, 108). Unfortunately, all of the chromosone values given 2n = 22 or 44 refer to the G. javanica classification system of Hermann (40). Therefore, until Vercourt's nomenclatural system for the subgenus Bracteata is used by cytologists and cytotaxonomists it is difficult to ascertain which of the sub-species of G. wightii contain diploids, tetraploids or both. Exceptions to the 2n = 22 or 44 chromosome values for G. wightii have been reported by Ramanthan (91) and Miège (73). They published 2n values of 20 and 40 for G. wightii. Plants of G. ussuriensis of the subgenus Soja are annual twiny vines with small narrow trifoliate leaves, purple flowers, and small, hard, almost round seed of a black to dark brown color. The species grows wild in Korea, Taiwan, Japan, throughout the Yangtze Valley, the Northeastern Provinces of China and the adjacent areas of the U.S.S.R. (33, 38, 40, 71, 76, 80, 84, 97, 98, 105, 106). Glycine ussuriensis which is commonly called in English wild soybeans, and in Japanese tsuru-mame or no-mame (80) has the most northern distribution of any species in the genus Glycine (40), l932, Tschechow and Kartaschowa (114) reported that G. ussuriensis had a 2n chromosone complement of 40. Fukuda (34) and Karasawa (40) also published similar diploid chromosone numbers for G.ussuriensis.

The economic importance of the genus Glycine lies within the subgenus Soja. Glycine max, the soybean, is a summer annual herb that has never been found in the wild (43). In 1925, Karpechenko (55) Soja hispida (syn. G. max) had a diploid chromosome number of 40. Soon afterward, cytological studies by other investigators (34, 50, 57, 120) confirmed Karpechenko's finding. Yamaha and Sinoto (128) and Ghimpu (35) were very much in the minority when they reported 2n chromosome values of 38.

Glycine max has many vernacular names of which soybean or soyabean are the most common. Ta tou and daidzu are the most currently commonly used vernacular names for the food-plant in China and Japan (87). In Thailand, Cochin-China and in Northern India G. max is known as tua luang, dau nanh and bhat, respectively (26, 46, 64). Additional vernacular names of G. max, may be obtained from Piper and Morse (87) and Ying and Grandvoinnet (129) who have published extensive lists.

Extensive interspecific crossing experiments between G. max and G. ussuriensis have been carried out by investigators who were attempting to determine the relationship between the species. The first reported interspecific cross as narrated by Fukuda (34) was made by Nakatomi and Nibe around 1917. According to Fukuda, the work was never published. Experiments by Fukuda, Karasawa, Tang and Tai, Tang and Chen, Ting, Weber and Williams (34, 50, 107, 109, 112, 123, 126) revealed that (a) the diploid and haploid chromosome number of both species and their Fl's were 40 and 20, respectively; (b) the size of the, chromosomes of both species were similar; (c) the fertility of the F1's and their progeny, were normal; and (d) the mode of inheritance of such characters as stem color, flower color, pod color, seed coat color, hilum color, pubescence color, pod bearing habit, bloom on seed, plant height, size of seed, shape of seed, shattering of pod, twining habit, hardness of seed, maturity date, protein and oil content were elucidated. The modes of inheritance of qualitative and quantitative characters in crosses between G. max and G. ussuriensis were essentially similar to crosses between two varieties of G. max. The above cytological results led Karasawa (50) to conclude that the "cultivated soybean might have been derived from the wild bean through the accumultion of qualitative and quantitative changes due to gene mutation without any chromosomal change."

Skvortzow (97) believed he had found a new Glycine species which is closely related to the cultivated crop G. max and the wild soybean G. ussuriensis. He named the weedy form which has characters intermediate between the cultivated and wild soybean G. gracilis. The U.S. Department of Agriculture Plant Inventory Records list contains G. gracilis accessions from China (Manchuria), Japan and Korea.

Fukuda (34) found that the diploid and haploid chromosome numbers and size of chromosomes of G. gracilis were the same as G. max and G. ussuriensis. Karasawa 4 (50, 57) was able to make G. max X G. gracilis hybrids quite easily, however, he was not able to make a G. gracilis x G. ussuriensis hybrid (51). Hermann (40) concluded that Skvortzow's G. gracilis did not seem to merit a nomenclatural designation and therefore he included G. gracilis in with G. max.

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