冷冻胁迫下方竹抗氧化酶活性和叶绿素荧光特性

以1年生盆栽实生方竹为材料,人工模拟冷害(4℃)、冻害(-5,-10,-20℃)和短时间(15,30,60 min)胁迫,测定抗氧化酶(CAT,POD,SOD)活性的变化,同时通过Imaging-PAM观测叶绿素荧光参数的变化,探讨方竹抵抗冷冻胁迫的机制。结果表明,冷害和冻害胁迫均可诱导方竹体内防御体系发挥作用,方竹叶片的相关抗氧化酶活性均表现出先升高后降低再升高的趋势,其中CAT和POD活性对低温胁迫的应答较为迟缓,而SOD活性对冷害和冻害胁迫的反应更灵敏。在冷害与冻害胁迫下,方竹叶片的叶绿素荧光参数Fv/Fm、Y(Ⅱ)、qP、ETR均呈现先降低后升高的趋势;与4℃低温的冷害胁迫相比较,冻害胁迫对光合作用的损伤更严重,其中在-20℃处理下,ETR、Y(Ⅱ)、qP皆为0,表明此时方竹已失去光合能力。

Preliminary studies on antioxidant enzyme activity and chlorophyll fluorescence parameters in Chimonobambusa quadrangularis under the condition of chilling and freezing stress

Using one-year old seedlings of Chimonobambusa quadrangularis as experimental material,effects of chilling(4 ℃) and freezing(-5,-10,-20 ℃) stress in a short time(15,30,60 minutes) on antioxidant enzyme(CAT,POD and SOD) activities and chlorophyll fluorescence parameters via Imaging-PAM instrument were investigated and observed,in order to explore mechanisms responding to chilling and freezing stress in Chimonobambusa quadrangularis.The results showed that among these antioxidant enzymes,compared with the responses of CAT and POD induced by chilling stress,changes of SOD activities were more sensitive both to chilling and to freezing stress.Moreover,chlorophyll fluorescence parameters,including Fv/Fm,Y(Ⅱ),qP and ETR,displayed the trend of "low-high" both in chilling and freezing conditions.However,fluorescence parameters under the cold-stress condition had greater changed scale than those under the freezing stress.ETR,Y(Ⅱ) and qP under the stress of-20 ℃ were hardly detected,suggesting plants had almost lost photosynthetic capacity.