Factors affecting the concentration of health-promoting phytochemicals in soybean

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Soybean [Glycine max (L.) Merr.] contains high concentrations of isoflavones and saponins, which both have putative health-beneficial properties. The North American market value for soybean isoflavones alone is of 500 million $. The proposed research program aims at providing an understanding of the factors affecting the concentrations of isoflavones and saponins in soybean. Specifically we will study the impact of environmental factors using statistical analyses to relate soybean isoflavones and saponin concentrations to a range of environmental variables (i.e., soil characteristics, climatic conditions, etc...). We will also determine if particular growth stages are most responsive to specific environmental factors, focusing on the impact of air temperature and soil moisture, which were reported to significantly affect isoflavone concentrations in soybean. In these studies we will look at the impact of several stress treatments on soybean isoflavone and saponin concentrations using HPLC, as well as gene expression. We will apply real-time QRT-PCR technology to quantify transcript levels of genes involved in isoflavone synthesis including phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), chalcone reductase (CHR), isoflavone synthase (IFS), malonyl transferase (MT), and glucosyl transferase (GT) at different stages of soybean growth development following treatments. We will attempt to establish a relation between the levels of phytochemicals found in soybean tissues with their respective gene expression. Previous work in our laboratory has demonstrated that elicitor compounds such as chitosan could be used to manipulate concentration and profile of isoflavones in soybean. This program will build on these findings by investigating the potential use of elicitor compounds including chitosan and methyl jasmonate to increase soybean saponin concentrations. Ultimately, this research could contribute to the development of new value-added markets and create economic opportunities for Canadian agricultural producers and associated agri-industries.