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Water-saturated soils and flooding (submergence) can greatly reduce soybean [Glycine max (L.) Merr.] yield. Mapping analyses with the simple sequence repeat (SSR) marker Sat_064 have identified a quantiative trait locus (QTL) for tolerance to waterlogging in the cultivar Archer. Our objectives were to evaluate the effect of this QTL on waterlogging tolerance in southern environments and genetic backgrounds, and to assess variability for waterlogging tolerance in Archer derived populations. We used Sat_064 genotype data to create seven sets of NILs from the populations A5403 x Archer and 9641 x Archer. The NILs were grown under waterlogged (water level 70-120 mm above the soil surface for 2 wk starting at flowering) and irrigated control conditions at three environments in 1999 and 2000 and evaluated each for yield and visual waterlogging injury. Waterlogging injury was rated on a 0 (no symptoms) to 9 (>90% severely chlorotic or dead) scale. Checks and select RILs from the same crosses were also tested. Additional RILs from each population were tested for waterlogging injury in 2000. The Sat_064 marker did not account for a significant portion of the variability among the NILs for either waterlogging tolerance based on yield, yield in waterlogged conditions, or waterlogging injury. This may be due to the southern genetic backgrounds and environments in this study as the Sat 064 QTL was originally identified in northern genetic backgrounds and environments. Variation for waterlogging tolerance and waterlogging injury was noted in the RIL populations. The most tolerant RILs suffered a 32% yield reduction from waterlogging and had a waterlogging injury rating of 1.3 while the most susceptible RILs suffered a 77% yield loss and had a waterlogging injury score of 6.8. The populations segregated for waterlogging tolerance independently of the Sat_064 marker. Visual assessment of waterlogging injury was associated with yield-based assessment of waterlogging tolerance and could be used to select for lines with improved waterlogging tolerance., EXCESS SOIL MOISTURE causes waterlogging (root or a portion of the shoot is submerged in water) or complete submergence, and is estimated to affect 12% of the agricultural soils in [...]

Soybean [Glycine max (L.) Merr.] is a rich source of isoflavones that are often affected by biotic and abiotic factors. The objectives of this study were to evaluate the effect of various concentrations of three natural elicitors applied at different soybean growth stages on isoflavone content and to compare the efficiency of several solvent systems in isoflavone extraction and quantification. The isoflavones extracted from R96-3444 soybean using eight solvent systems were separated, identified, and quantified by a high-performance liquid chromatography (HPLC) procedure. The soybean plants were sprayed with salicylic acid, methyl salicylate, or ethyl acetate at 0, 10(-6), 10(-3), and 10(-1) M at R1 (blooming) or R4 (full pods) growth stage. Results showed that 10(-3) M ethyl acetate sprayed at the R1 stage significantly increased total isoflavone content and the levels of some individual isoflavones in soybean seeds. With all the elicitors that were tested, concentration was a more important factor than application time with respect to isoflavone content with lower concentrations being more effective on most isoflavones. A 53% acetonitrile solvent system was the best solvent system for extracting total isoflavone, malonyl glucosides, genistein, glycitin, genistin, acetyl-daidzin, and acetyl-genistin. The results of this study will be useful for increasing the isoflavone content in desirable soybean varieties and improving isoflavone concentration during extraction.