| In recent years, soybean isoflavones have been received considerable attention because of their important function in the prevention and the treatment to chronic human diseases from the data of a number of reports, and tofu as a traditional soybean food invented by Liu An, the King of Huai-Nan (B.C. 179-122), has become greatly popular all over the world. The big differences in quality property of soybeans exist among eco-regions in China with vast land, complex eco-factors and multiplex cultures of diet, and there may be a great genetic diversity of soybean germplasms including wild material, landrace and released cultivar. Investigating the variation and inheritance mechanism of tofu and soymilk output and isoflavones content of soybean germplasms in the whole country and different eco-regions in China is of great significance to soybean tofu, soymilk and isoflavones quality breeding, and to the improvement of soybean quality property.A great many studies have been carried out on tofu, soymilk and isoflavones, but the majority of them aimed at sensory quality of tofu and soymilk, isofiavone contents of soyfoods and their function. Few reports has been published on systematic study of the variability of tofu and soymilk output and 12 isoflavones contents with a large samples consisted of wild materials, landraces and released cultivars from different varietal eco-regions in China,and the inheritance and mapping QTL of tofu and soymilk output and 12 individual isofiavone content of seeds, soymilk and tofu with RIL population. In the present study, under the methods to be established of tofu and soymilk output for large amount of mini-specimens and of 12 isoflavones contents for large amount of soybean germplasms and processing products, 946-983 accessions, including 564-580 landraces, 101-106 released cultivars, 193-209 wild materials from various eco-regions in China and 88 released cultivars from abroad were tested for their dried tofu and soymilk output, 12 isoflavones contents to analysis their variabilities in China and in different eco-regions; Segregation analysis for tofu and soymilk output, total and individual isoflavone content of seeds, tofu and soymilk in two cropping years (2004 and 2005) were conducted on a RIL population (NJRIKY) with 184 lines derived from Kefeng No.1×Nannong 1138-2 under the Major Gene Plus Polygene Mixed Inheritance Model according to Gai et al.(2003), Based on a genetic linkage map, which spanned 4226.40 cM with 488 markers in 25 linkage groups, constructed from NJRIKY,the QTLs of tofu and soymilk output, total and individual isoflavone content of seeds, tofu and soymilk were mapped under the composite interval mapping (CIM) procedure of the software Cartographer V. 2.5 according to Wang et al.(2005). The main results were as follows:1.Based on the previous methods, by using FOSS Tecator 1095 Sample Mill with grinding speed of 20000 rpm, the effects of grinding time, filter sieve size and filtering method for tofu and soymilk output were mainly studied. The result showed that the procedure with a grinding time 50 s and filtering through 120 or 100 mesh nylon sieve under 0.098 Mpa with a cycling water vacuum pump for 1 min provided the highest output and lowest error for measurement of dried tofu and soymilk output. A mini-specimen technology for tofu and soymilk output for large amount of mini-specimen was developed for standardization of tofu and soymilk output in laboratory. A large number of experiments (more than 4000 samples) indicated that the improved method has the characteristics of being fast, accurate and efficient.2.The results from analysis variability of dried tofu and soymilk output of 946 accessions indicated there existed large variation in dried tofu and soymilk output both in cultivated and wild soybeans in China,with a range of 25.32-69.59 and 25.52-85.89 g 100 g-1 for dried tofu output and 40.75-82.86 and 39.05-91.86 g 100 g-1 for dried soymilk output, respectively. Dried tofu output have respectively increased 11.33 and 12.41 g 100 g-1 in landraces and released cultivars both on the foundation of wild soybeans with the average of 45.75 g 100 g-1,while the soymilk output increased 13.03 and 13.43 g 100 g-1 based on the wild soybeans with the average of 61.46 g 100 g-1,respectively. The improvement of dried tofu and soymilk output was mainly the result of artificial evolution in thousands of years. The results in various eco-regions showed a similar trend as that in the whole country. The variation in dried tofu and soymilk output within an eco-region was more than that inter eco-regions; and there existed a weak geographical variation for cultivated soybeans, especially in some southern eco-regions, which might be due to the accumulation from artificial selection since there was no similar trend naturally for wild soybean.3.The results from segregation analysis showed that both tofu and soymilk output were controlled by two major genes plus polygenes, with the major gene heritability of 13.23%-26.84%, and polygene heritability of 73.15%-86.77%. The results of QTL mapping showed two linked QTLs associated with tofu output were identified, explaining 16.23%-23.18% of the total phenotypic variation. One QTL related with soymilk output was found, explaining 4.73%-7.14% of the total phenotypic variation. Both tofu and soymilk output in soybean were controlled under major genes with smaller heritability and polygenes with heritability more than 73.15%, which indicated to accumulate polygenes should be emphasized in the improvement of tofu and soymilk output. The results between segregation analysis and QTL mapping appeared somewhat consistent, therefore could be used for verification each other.4.A high-performance liquid chromatography (HPLC) method was established to resolve 12 isofiavones of soybean seeds, tofu and soymilk for less than 15 min using Agilent 1100 HPLC system with a diode array detection (DAD) and a C18 packing column (5μm,4.6 mm×150 mm). The method showed to be linear with the r2 more than 0.999, precision with the RSD less than 5% for over 5700 samples, accurate with the recoveries above 99.00% for the different concentrations of the 12 isofiavones and with the RSD ranged from 0.22% to 1.40% intra- days, and robust with the RSD of 0.24-3.95% inter-days.5.The results from analysis variability of total and individual isoflavone content from 983 accessions indicated that:(1)There existed 12 isoflavone content in the majority of cultivated and wild soybeans in China, and the perception each content occupys in different materials differs from each other, wild and landrace soybeans have the higher percentage of daidzin group content, with the average of 46.81% and 35.40%, respectively, released soybeans have the higher percentage of glycitin group content, with the average of 48.00%.(2) There existed large variation in total and individual isoflavone content both in cultivated and wild soybeans in China,with a range of 927.29-7932.94, 259.38-7725.45 and 547.49-5735.15μg g-1 for total isoflavone content (ISF) in wild materials, landraces and released cultivars, respectively. Based on wild materials with the average of 2994.51μg g-1,those of landraces with the average of 3241.33μg g-1 increased 246.82μg g-1,while released cultivars with the average of 2704.83μg g-1 decreased 289.68μg g-1.Among the isoflavones for landraces and released cultivars, total daidzin group content (TD) reduced 233.08 and 975.64μg g-1 for landraces and released cultivars based on the wild material with the average of 1386.8μg g-1 for TD, respectively, total genistin content (TG) elevated 211.83 and 217.83μg g-1 on the average of 791.53μg g-1 of the wild material, total glycitin group content (TGL) grew 268.07 and 468.15μg g-1 on the average of 816.10μg g-1 of the wild material, respectively, indicated that the released cultivars with the main improving purpose of output have obviously decreased the perception of daidzin group content, lead to the result that the total isoflavone content of released cultivars was lower than the wild soybeans in average. (3) The results in various eco-regions showed a similar trend as in the whole country. The variation in total and individual isoflavone content within an eco-region was more than that among eco-regions. (4) Total isoflavone content of cultivated soybeans existed negative relationship both with longitude (r=-0.264) and latitude(r=-0.264) significantly at P<0.01 level, while no similar trend naturally for wild soybean, indicated that the soybean isoflavone content has no relationship with the original region of germplasms, and eco-regions formed the weak relationship between those of cultivated soybeans with both longitude and latitude from the difference of artificial selections.6.The results from segregation analysis showed that total and individual content of seeds were controlled by two or three major genes plus polygenes, with the major gene heritability of 16.42%-45.08%, and polygene heritability of 54.78%-83.44%; The results of QTL mapping showed that more than 28 QTLs associated with isoflavone content were identified with composite interval mapping (CIM),explaining 3.98%-13.21% of the total phenotypic variation. Among them, the two QTLs were associated with total isoflavone content in seeds, explaining accumulatively 15.55%-15.60% of the total phenotypic variation, and no locus was associated both with total and individual isoflavne content, suggesting that the effect of the QTLs of individual isoflavone content was too small to appear in those of total isoflavone content. Both total and individual isoflavone content insoybean seeds were controlled under major genes with smaller heritability and polygenes with heritability more than 54.78%, which indicated to accumulate polygenes should be emphasized in the improvement of isoflavone content. The results between segregation analysis and QTL mapping appeared somewhat consistent,therefore could be used for verification each other. 7.Joint statistic analysis of total and individual isoflavone content of processing products from NJRIKY seeds of 2004 and 2005 cropping years showed that total isoflavone of seeds in processing tofu was transported 14.85% to residual, 85.15% to soymilk, then 17.32% to tofu and 67.83% to whey. The trend occured in 184 lines and their parents and differed from each other, with being ranged from 78.93% to 88.70% of total isoflavone content in tofu,from 5.61% to 43.03% of total isoflavone content in soymilk and from 38.67% to 81.45% of total isoflavone content in whey. Thus, it should be possible to breed for isoflavone content in processing products in a cultivar development program, and to increase or decrease isoflavone content in soybean products by processing procedure.8.The segregation analysis and QTL mapping of 12 total and individual isoflavone content of dried tofu and soymilk from NJRIKY seeds of 2004 and 2005 cropping years showed that: (1) The total and individual isoflavone of dried soymilk were controlled by two or three major genes plus polygenes, with the major gene heritability of 29.66%-49.27%, and polygene heritability of 50.59%-70.20%. More than 12 QTLs associated with individual isoflavone content of dried soymilk were identified with CIM, explaining 4.09%-13.51% of the total phenotypic variation. 4 QTLs associated with total isoflavone content of soymilk were mapped only in single year, explaining 4.74-6.95% of the total phenotypic variation. (2)The total and individual isoflavone of dried tofu were controlled by two major genes plus polygenes, with the major gene heritability of 9.27%-47.50%, and polygene heritability of 52.37%-90.60%. Over 10 QTLs related with total and individual isoflavone of dried tofu were found, explaining 4.08%-20.06% of the total phenotypic variation, in which 2 QTLs associated with total isoflavone content of tofu, accumulated explaining below 20% of the total phenotypic variation,. Both total and individual isoflavone content in dried soymilk and tofu were controlled under major genes with smaller heritability and polygenes with heritability more than 50.59%, which indicated to accumulate polygenes should be emphasized in the improvement of isoflavone content. The results between segregation analysis and QTL mapping appeared somewhat consistent, therefore could be used for verification each other.9.Forty elite accessions were screened out for different quality breeding purposes, including double high tofu and soymilk output,high total isoflavone content, high TD, high TG and high TGL, such as Nannongdahuangdou (DT and DM were 79.95 of 92.87 g 100 g-1), ZYD3621 (ISF was 7932.94μg g-1),N3208 (TD was 4901.83μg g-1),N23602 (TG was 3747.24μg g-1) and N20793 (TGL was 5122.21μg g-1), etc. |
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