| Summary: | 博士 === 國立中興大學 === 農藝學系 === 93 === Three perennial Glycine species, G. tabacina, G. tomentella and G. dolichocarpa, are known to be native to Taiwan. In King-Men, G. tomentella is an economical crop. Its roots are used as the source of the crude drug, “I-Tiao-Gung,” which is used in various health care products. The roots of wild G. tabacina in Pong-Fu, as well as G. tomentella in Ping-Tong, are also used as the source of I-Tiao-Gung. While I-Taio-Gung has been used for medical purposes for many years, little work has been done on the identification of the botanical origin of its source plants.
In this study, the main components and variations among the three wild soybean species in Taiwan are investigated. The seasonal variation of marker components are also investigated to identify the harvesting periods for crude drug uses. Species collected from different locations were cultivated in the same farm to determine the suitable “variety” of “I-Tiao-Gung” based on the variations of marker components. Also, the population variations of the botanical origins are studied based on anatomical characters. The results of this study can serve as selection and quality parameters in Glycine germplasm, in collection programs, and in herbal medicine cultivation.
These three species of perennial wild soybean are evaluated based on the isoflavone contents in four different organs. The results indicate that G. tabacina has the highest total isoflavone contents, followed by G. tomentella, and G. dolichocarpa has the least. The root is found to have the highest contents of isoflavones, followed by the stem. Daidzein is the major isoflavone constituent in roots, followed by daidzin. These two components, daidzein and daidzin, accounts for over 99﹪of the total isoflavones, and are the major component of these three wild soybean species.
The three species of perennial wild soybean were planted in the same farm to investigate the seasonal variation of isoflavone contents in a one year period. The results show that total isoflavone contents lowered during flowering stage in all three species and reached the highest level in the autumn and the winter. October and December are the suitable harvest time for G. tabacina（Duchr population）. October is suitable for G. tomentella（Hengchuen population）and G. dolichocarpa（Dunghe population）. Also, the isoflavone contents can be increased by suitable culture as indicated by our results.
Significant differences in isoflavone contents exist among the three populations of G. tabacina, three populations of G. tomentella, and two populations of G. dolichocarpa, planted in the same field. Baisha population of G. tabacina has the highest total isoflavone contents, followed by Duchr, and Shagang has less. There appears to be geographical genetic variations in G. tabacina plant components, and there is variation among populations in species. The populations of G. tabacina in Pong-Fu have higher isoflavone aglycone and glucoside contents, and the population of Baisha has the highest. For germplasm conservation, the plants should be collected from different locations, and special attention needs to be paid to the Baisha population.
The anatomical characters of the roots of 12 populations of Glycine species in Taiwan are studied and used to identify the geographical and interspecies variations. The results show that G. tabacina can be distinguished by the length and width of cork cell, the length and width of cortex cell, the vessel diameter, and the xylem ray among populations; G. tomentella by the length and width of cork cell, the cambium, and the diameter of starch grain; and G. dolichcarpa by the number of cork cell layers, the length and width of cork cell, the number of cortex cell layers, the length of cortex cell, the width of cortex cell, and the diameter of clustered crystal and vessel . The differences between the species of G. tabacina and G. tomentella are follows: G. tabacina has larger cortex cell length and width, smaller clustered crystal and vessel diameters. Between the species of G. tabacina and G. dolichcarp, G. tabacina has larger cortex cell length, smaller starch grain, clustered crystal, and vessel diameters. Between the species of G. tomentella and G. dolichcarp, G. tomentella has larger cortex cell length, smaller cortex cell width, larger starch grain and vessel diameters. G. max has smaller cortex cell width and vessel diameter than other species and has no starch grain. These characters can be used to distinguish the differences among species.
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