干旱胁迫对苔闽苣苔光合作用和抗氧化酶的影响

Effects of Drought Stress on Photosynthesis and Antioxidant Enzymes of Titanotrichum oldhamii

摘要: 台闽苣苔是我国特有的珍稀濒危植物，为了解台闽苣苔栽培中的水分需求问题。以台闽苣苔为试材，研究干旱胁迫对台闽苣苔气体交换、叶绿素荧光和抗氧化酶的影响。结果表明，干旱胁迫使台闽苣苔净光合速率(Pn)和气孔导度(Gs)明显下降；台闽苣苔Fv/Fm、Fv’/Fm’、ΦPSII、qP和ETR在干旱胁迫下也呈持续下降趋势，表明干旱胁迫下台闽苣苔的开放PSII反应中心部分和PSII反应中心光能转换效率都下降，从而降低了电子传递能力，导致Pn的降低。但干旱胁迫后，台闽苣苔的非光化学猝灭(NPQ)和超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性明显上升，说明台闽苣苔启动了天线色素的热耗散和抗氧化酶系统，但这些防御反应可能不足以及时地有效地耗散过剩激发能和清除活性氧物质，从而使干旱胁迫下台闽苣苔的Pn仍持续下降。

Abstract: Titanotrichum oldhamii is a rare and endangered plant unique to China. In order to address the water demand issue in the cultivation of T. oldhamii, we used T. oldhamii as the test material, the effects of drought stress on gas exchange, chlorophyll fluorescence, and antioxidant enzymes were studied. The results showed that drought stress significantly reduced the net photosynthetic rate (Pn) and stomatal conductance (Gs) of T. oldhamii; The Fv/Fm, Fv’/Fm’, ΦPSII, qP, and ETR of T. oldhamii also showed a continuous downward trend under drought stress, indicating that the open PSII reaction center and PSII reaction center light energy conversion efficiency of T. oldhamii decreased under drought stress, thereby reducing its electron transfer ability and leading to a decrease in Pn. However, after drought stress, the non-photochemical quenching (NPQ), superoxide dismutase (SOD) activity, and peroxidase (POD) activity of T. oldhamii significantly increased, indicating that T. oldhamii has activated the heat dissipation and antioxidant enzyme system of antenna pigments, but these defense reactions may not be sufficient to effectively dissipate excess excitation energy and clear reactive oxygen species in a timely manner, resulting in a continuous decrease in Pn of T. oldhamii under drought stress.