低温胁迫下菊花叶片叶绿素荧光特性与抗氧化酶活性的变化

Chlorophyll Fluorescence Characteristics and Antioxidant Enzyme Activities of Chrysanthemum Leaves under Low Temperature Stress

以秋菊晚花品种金龙腾云为材料,研究其在不同温度下叶片叶绿素荧光参数和抗氧化酶活性等生理生化指标的变化,探讨其低温响应机制。结果表明:与对照组相比,8、4、-4、-8℃处理12 h叶绿素a+b含量分别下降了14.6%、23.2%、45.7%和49.9%,可溶性糖含量分别增长了16.5%、19.4%、19.7%和23.2%。8℃和4℃处理组,菊花叶片Fv/Fm、Fv/Fo和q P变化趋势不明显,NPQ在处理3 h时表现出上升趋势,随着处理时间的延长8℃条件下NPQ的变化趋于平缓,而4℃条件下NPQ缓慢降低;而-4、-8℃条件下Fv/Fm、Fv/Fo、q P和NPQ均大幅度降低,-8℃处理12 h,q P、NPQ几乎为0。8、4℃处理组,菊花叶片处理3 h SOD、POD活性显著增加,而CAT活性在处理3 h时表现出下降趋势,随后逐渐升高;而-4、-8℃处理时,SOD、POD活性处理3 h时达到峰值后迅速下降,CAT活性随着处理时间的延长显著下降。与对照组相比,低温下处理12 h时,MDA含量分别增长了11.9%、17.3%、54.2%和60.7%。综上表明,低温伤害较轻时,菊花可以通过调节抗氧化酶活性、可溶性糖含量,增加热耗散等生理机制来减轻低温胁迫程度;而随着温度的降低,受冻害严重的植株(-8℃),抗氧化酶活性显著下降,MDA含量显著升高,叶绿素荧光参数大幅度降低,光系统受到严重伤害,已基本失去光合作用能力。

Autumn chrysanthemum late-flower cultivar Jinglongtengyun was used as experimental material.The effects of different temperature on antioxidant enzyme activities and chlorophyll fluorescence parameters were studied in order to explore mechanisms in response to low temperature.The results are as followes：in contrast with CK,under 8,4,-4 and-8 ℃ treatments for 12 h the chlorophyll a ＋ b content in leaves decreased by 14.6％,23.2％,45.7％ and 49.9％ respectively and the soluble sugar content increased by 16.5％,19.4％,19.7％ and 23.2％.Under 8 ℃ and 4 ℃ treatments,the trends of Fv/Fm,Fv/Fo and qP were not obvious,but NPQ increased at the early stage.With the increase of treatment time,the trend of NPQ was not obvious at 8 ℃ and decreased slowly at 4 ℃.Under-4 ℃ and -8 ℃ treatments,Fv/Fm,Fv/Fo,qP and NPQ decreased significantly,qP and NPQ were close to zero under-8 ℃ treatment for 12 h.Under 8 ℃ and 4 ℃ treatments,SOD and POD activities increased significantly at 3 hours after treatment,CAT activity decreased at 3 h and then increased.SOD and POD activities increased firstly and then decreased,and CAT activity appeared declining trend under-4 ℃ and -8 ℃ treatments.Under low temperature for 12 h,the MDA content in leaves increased by 11.9％,17.3％,54.2％ and 60.7％.In sunmary,autumn chrysanthemum could relieve low temperature stress by regulating antioxidant enzyme activity,content of soluble sugar,and increasing heat dissipation.However,fluorescence parameters and antioxidant enzyme activity in leaves of chrysanthemum decreased significantly at-8 ℃,and the photosynthetic system was seriously damaged,leading to the loss of photosynthetic capability.