Photosynthetic performance of Antarctic lichenDermatocarpon polyphyllizumwhen affected by desiccation and low temperatures
Photosynthetic performance of Antarctic lichenDermatocarpon polyphyllizumwhen affected by desiccation and low temperatures
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DOI：
10.1007/s11120-020-00773-4
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发表时间：
2020-07-27
影响因子：
3.7
通讯作者：
Bartak, Milos
中科院分区：
文献类型：
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作者：
Bednarikova, Michaela;Vaczi, Peter;Bartak, Milos
地衣是一种共生生物，能够很好地适应干燥/再水化循环。在过去的几十年里，人们通过多种生物物理方法在地衣光生物II光系统水平上研究了其光合反应的生理背景，特别是在干燥过程中保护机制的激活。本研究研究了干燥和低温对南极多叶绿果（chlorolichenDermatocarpon polyphyllizum）叶绿素荧光和光谱反射参数的影响。在南极洲詹姆斯罗斯岛采集地衣菌体，将样品转移到实验室，在18、10和4℃的温度下进行充分水化和干燥，在干燥过程中，用重量法测量相对含水量（RWC），并反复测量与叶绿素荧光快速瞬态（OJIP）相关的光合参数。同样，在菌体脱水过程中监测光谱反射参数（如NDVI、PRI、G、NPCI）的变化。脱水响应曲线显示，ojip衍生的大部分参数（如光系统II光化学最大量子产率：F-V/F-M）和性能指标：PI d . polyphyllium)均有所下降，且在RWCs低于20%时更为明显。严重脱水菌体的热耗散（DI0/RC）和量子产率（Phi_D-0）的增加证明了保护机制的激活。低温加速了这些过程。对OJIP形状的分析表明，存在k波段（300 μ s）和l波段（80 μ s），这可归因于脱水诱导的应力。在大多数情况下，光谱反射率指数随着RWC的降低而降低，并与ojip衍生的参数F-V/F-M（PSII中光合过程的能力）、Phi_E-0（电子传递有效性）和PI_tot（总性能指数）呈正相关，这在NDVI中更为明显。与NPCI呈负相关。这些指标可用于地衣复水/脱水循环的后续生态生理光合研究。
Lichens are symbiotic organisms that are well adapted to desiccation/rehydration cycles. Over the last decades, the physiological background of their photosynthetic response-specifically activation of the protective mechanism during desiccation-has been studied at the level of photosystem II of the lichen photobiont by means of several biophysical methods. In our study, the effects of desiccation and low temperatures on chlorophyll fluorescence and spectral reflectance parameters were investigated in Antarctic chlorolichenDermatocarpon polyphyllizum.Lichen thalli were collected from James Ross Island, Antarctica, and following transfer to a laboratory, samples were fully hydrated and exposed to desiccation at temperatures of 18, 10, and 4 degrees C. During the desiccation process, the relative water content (RWC) was measured gravimetrically and photosynthetic parameters related to the fast transient of chlorophyll fluorescence (OJIP) were measured repeatedly. Similarly, the change in spectral reflectance parameters (e.g., NDVI, PRI, G, NPCI) was monitored during thallus dehydration. The dehydration-response curves showed a decrease in a majority of the OJIP-derived parameters (e.g., maximum quantum yield of photosystem II photochemistry:F-V/F-M, and performance index: PI inD. polyphyllizum, which were more apparent at RWCs below 20%. The activation of protective mechanisms in severely dehydrated thalli was documented by increased thermal dissipation (DI0/RC) and its quantum yield (Phi_D-0). Low temperature accelerated these processes. An analysis of the OJIP shape reveals the presence of K-bands (300 mu s), and L-bands (80 mu s), which can be attributed to dehydration-induced stress. Spectral reflectance indices decreased in a majority of cases with an RWC decrease and were positively related to the OJIP-derived parameters:F-V/F-M(capacity of photosynthetic processes in PSII), Phi_E-0(effectiveness of electron transport), and PI_tot (total performance index), which was more apparent in NDVI. A negative relation was found for NPCI. These indices could be used in follow-up ecophysiological photosynthetic studies of lichens that are undergoing rehydration/dehydration cycles.