Exogenous spermidine improves drought tolerance in Phyllostachys edulis seedlings

摘要

Phyllostachys edulis is an endemic and dominant bamboo species in southern China. It suffers often from seasonal drought during the cultivation process. In the present study, the effect of exogenous spermidine (Spd) on the following parameters of leaves of Phyllostachys edulis seedlings under drought stress were studied: The generation rate of superoxide free radical, proline content, REC, MDA content, RWC, Chlorophyll content; and activities of POD, SOD and CAT. The drought stress was caused by 20% polyethyle glycol (PEG) and three concentrations of spermidine were applied (0.0l mmol/LSpd, 0.1 mmol/LSpd, 1.0 mmol/LSpd). Drought stress caused a decrease?in growth rate which was related to several physiological changes: decreasing RWC and chlorophyll content and increasing generation rate of superoxide free radical, increasing MDA and REC, and increasing activities of POD and CAT. Foliar application with 0.01mM exogenous Spdincreased POD activity and RWC, but had no effect on SOD activity, Chl(a+b) or Chla/Chlb and also no significant effect on proline content, activity of P5CS, or generation rate of superoxide free radical. The 0.1 mM application with exogenous Spd significantly increased the chlorophyll content and RWC, inhibited the generation rate of superoxide free radical, reduced membrane lipid per-oxidation, returned the activities of antioxidant enzymes to the normal level, and minimized the increases in REC, proline, and MDA content. Application with the highest spermidine concentration (1.0mM Spd) has the same effects apart from the increase of H 2 O 2 content. In conclusion, application with 0.1 mM exogenous Spd can effectively alleviate a series of physiological and biochemical changes caused by drought stress in the bamboo trees. This may provide more insight to the possible mechanisms of how exogenous polyamines can influence the drought resistance of Phyllostachys edulis and in this way facilitate the cultivation of this bamboo species under drought stress.