Application of RP-HPLC for the determination of isoflavonoid content in soybean roots as effect of chilling stress

Soybean (Glycine,nax. [L] Merr.) is a subtropical legume and requires a tem perature In range 25-30 degrees C. Phenylalanine ammonia-lyase (PAL, EC.4.1 .3.5) which catalyzes deamination of L-phenylalanine to trans-cinnamic acid is regarded as enzyme that leads to phenylpropanoids, such as flavonoids, which can protect plants againts biotic and abiotic stresses. Additionaly f lavonoids are known as very effective anticancer protectants in herb al med icine. The very useful method for identification and quantitation of flavon oids is HPLC technique with the use of UV/VIS, DAD and MS detection. At a s uboptimal root-zone temperature there is a decrease in soybean roots growth proportional to the decrease in temperature. In our experiment the PAL act ivity increases at 5 degrees and 10 degrees C but does nor change at 15 deg rees C in comparison to the control. Preliminary RP-HPLC analyses of isofla vonoids in control roots letter transferred to the temperature 10 degrees C showed that the composition of flavonoids were changed in the chilled root s. We suggest that FAL and its products can disturb: (1) root growth of see dlings, (2) nodule numbers and (3) symbiotic relationships between the soyb ean and Bradyrrhizobium.