[Effect of BBM gene on callus growth and ginsenoside content in Panax quinquefolius]

Baby Boom(BBM) gene is a key regulatory factor in embryonic development and regeneration, cell proliferation, callus growth, and differentiation promotion. Since the genetic transformation system of Panax quinquefolius is unstable with low efficiency and long period, this study attempted to transfer BBM gene of Zea mays to P. quinquefolius callus by gene gunship to investigate its effect on the callus growth and ginsenoside content, laying a foundation for establishing efficient genetic transformation system of P. quinquefolius. Four transgenic callus of P. quinquefolius with different transformation events were obtained by screening for glufosinate ammonium resistance and molecular identification by PCR. The growth state and growth rate of wild-type and transgenic callus were compared in the same growth period. The content of ginsenoside in transgenic callus was determined by ultra-high performance liquid chromatography-triple quadrupole mass spectrometry(UPLC-MS/MS). The results showed that transgenic callus growth rate was significantly higher than that of wild-type callus. In addition, the content of ginsenoside Rb_1, Rg_1, Ro, and Re was significantly higher than that in wild-type callus. The paper preliminarily proved the function of BBM gene in promoting growth rate and increasing ginsenoside content, which provided a scientific basis to establish a stable and efficient genetic transformation system for Panax plants in the future.