冻融过程对生物结皮中齿肋赤藓叶绿素荧光特性的影响

摘要/Abstract

摘要： 以新疆古尔班通古特沙漠苔藓结皮中的优势种齿肋赤藓（Syntrichia caninervis Mitt．）为研究对象，利用便携式调制叶绿素荧光仪Mini-PAM（Walz公司，德国）测定其在冻融作用影响下叶绿素荧光特性的变化特征。结果表明,冻结过程中随着处理温度的降低，齿肋赤藓的初始荧光（F0）、最大荧光产量（Fm）、PSⅡ的最大光化学效率（Fv /Fm）、PSⅡ的潜在活性（Fv /F0）、PSⅡ实际光化学效率（ΦPSⅡ）、光合电子传递速率（ETR）和光化学猝灭系数（qP）均呈显著下降的趋势（P<0.05），而非光化学猝灭系数（NPQ）则逐步上升。低温胁迫下NPQ的增加表明齿肋赤藓PSⅡ系统通过提高非辐射性热耗散消耗过剩光能，从而保护PSⅡ反应中心免受因吸收过多光能而引起的光氧化伤害。消融过程中，齿肋赤藓的叶绿素荧光参数（F0、Fm、Fv /Fm、Fv /F0、ΦPSⅡ、ETR和qP）可恢复至未冻结前的正常水平。齿肋赤藓叶绿素荧光强度和诱导曲线的形状在冻融过程中均随处理温度的降低或升高而发生了明显的变化。一定范围内的低温胁迫不会对齿肋赤藓的光合器官造成永久伤害，光合系统仍维持在可恢复的状态。

关键词: 齿肋赤藓, 生物结皮, 冻融, 叶绿素荧光

Abstract: The tolerance to freezing and thawing of Syntrichia caninervis, the dominant species of moss crusts in the Gurbantunggut Desert, China, was investigated using a pulse-modulated fluorometer. The experiments described in this paper were carried out under controlled environmental conditions in a laboratory. Results showed that freezing caused significant decreases in the initial fluorescence yield (F0), the maximal fluorescence yield (Fm), the maximal photochemical efficiency of PSⅡ (Fv/Fm), the potential photochemical efficiency of PSⅡ (Fv /F0), the actual photochemical efficiency of PSⅡ(ΦPSⅡ), the relative rate of electron transport (ETR), and the photochemical quenching coefficient (qP) of S. caninervis (P<0.05), while the non-photochemical quenching coefficient (NPQ) increased gradually. The enhancement of NPQ observed in S. caninervis during freezing process indicated it might protect the photosynthetic structures from photooxidative damage. The rapid recovery of photosynthetic activities in S. caninervis during thawing process suggested that it was capable of tolerating the freezing and thawing cycles. Finally, the chlorophyll fluorescence parameters could recover to their original values at the beginning of freezing. In addition, the chlorophyll fluorescence intensity and the shape of the inductive curve in S. caninervis were strongly affected by the changes of temperature during freezing and thawing. It can be concluded that the photosynthetic structures of S. caninervis remained intact within a certain range of low temperature and the recovery of the chlorophyll fluorescence was reversible upon thawing. The freezing tolerance of S. caninervis is of great ecological significance in an exceedingly harsh desert environment with snow cover in winter.

Key words: Syntrichia caninervis, biological soil crusts, freezing and thawing, chlorophyll fluorescence

中图分类号:

Q945

张静;张元明*. 冻融过程对生物结皮中齿肋赤藓叶绿素荧光特性的影响[J]. 中国沙漠, 2011, 31(6): 1479-1487.

ZHANG Jing;ZHANG Yuan-ming. Effects of Freezing and Thawing on Chlorophyll Fluorescence of Syntrichia Caninervis in Biological Soil Crusts[J]. JOURNAL OF DESERT RESEARCH, 2011, 31(6): 1479-1487.

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