Abstract
Legume plants have an ability to fix atmospheric nitrogen via symbiosis with soil microbes. The secretion of flavonoids from legume roots is the initiation of nodule formation process, but almost nothing is known about the membrane transport mechanism of flavonoid molecules from root cells. We performed the first biochemical characterization of the transport mechanism of flavonoid from legume roots using soybean and the signal flavonoid genistein as a model system.
Plasma membrane vesicles were purified by fractionation of microsomes prepared from soybean roots on a discontinuous sucrose density gradient. The genistein transport by plasma membrane vesicles, which was analyzed by HPLC, was critically dependent on the hydrolysis of MgATP. The activity was inhibited by a typical inhibitor of ABC transporters vanadate, while it was insensitive to ionophore, suggesting the involvement of an ABC transporter in the secretion of flavonoids from soybean roots.
