Functional analysis of type II chalcone isomerase () genes in regulating soybean (.) nodule formation.

Biological nitrogen fixation (BNF) is the most cost-effective and environmentally benign method for nitrogen fertilization. Isoflavones are important signaling factors for BNF in leguminous plants. Whether chalcone isomerase (), the key enzyme gene in the flavonoid synthesis pathway, contributes to soybean () nodulation has not yet been fully clarified. In the present study, we identified the functions of three types of for BNF using a hairy root system. The results showed that and positively increased nodulation while did not, with the gene having a greater effect than . Meanwhile, the daidzein and genistein contents were significantly increased in composite plants overexpressing and reduced in composite plants, thus interfering with . However, overexpression of significantly increased the content of glycitein but not daidzein, genistein content implied that homologous genes exhibit functional differentiation. These results provide a reference for subsequent studies on improving nitrogen fixation in soybeans and providing functional genes for the improvement of new varieties.