[Effects of exogenous polyamines on the growth and activities of H+-ATPase and H+-PPase in cucumber seedling roots under hypoxia stress].

The effects of exogenous polyamines on the growth, polyamines contents, the activities of H(+)-ATPase and H(+)-PPase of plasma membrane and tonoplast in cucumber seedling roots under root-zone hypoxia stress were studied under hydroponic culture. The results showed that the growth of cucumber roots was significantly inhibited by hypoxia stress (Table 1). While the growth inhibition in cucumber roots by hypoxia stress could be alleviated by spraying exogenous polyamines. From these results (Table 1 and 2) we can conclude that Spd played an active physiological role in relieving hypoxia stress and Put exerted actively physiological role by enhancing Spd biosynthesis. The results also showed that the endogenous polyamine contents in cucumber roots were increased by hypoxia stress and spraying exogenous polyamines. Exogenous polyamines application obviously promoted the H(+)-ATPase activities of plasma membrane in cucumber roots (Fig.1), but did not significantly affect the H(+)-ATPase and H(+)-PPase activities of tonoplast in cucumber roots (Fig.2,3). The results suggested that exogenous polyamines could enhance hypoxia resistance of cucumber seedlings by increasing H(+)-ATPase activities of plasma membrane in cucumber roots.