Lange O L, Green T G A, Reichenberger H, Hesbacher S, Proksch P
Julius-von-Sachs-Institut für Biowissenschaften der Universität Würzburg, Mittlerer Dallenbergweg 64, D-97082 Würzburg, Germany, , , , , , DE.
Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton, New Zealand, , , , , , NZ.
Oecologia. 1997 Sep;112(1):1-3. doi: 10.1007/s004420050275.
Many lichens show seriously depressed net photosynthesis (NP) at high thallus water contents due to increased carbon dioxide diffusion resistance through blockage of diffusion pathways by water. The soil lichen Diploschistes muscorum, however, shows no depression and NP is close to maximal even at the highest thallus water content. We investigated whether lichen substances (lecanoric and diploschistesic acids) in the cortex and medulla contributed to this ability to maintain high NP. Dry thalli were extracted with water-free acetone and, after this treatment, were found to be fully viable to the extent of continued growth after replanting in the field. No differences were found in the response of NP to thallus water content between the normal and extracted thalli, in fact the response curves were often nearly identical. Thus, in this species it seems that lichen substances did not maintain the water-free diffusion pathways and some other explanation, possibly structural, needs to be sought.
许多地衣在藻体含水量较高时，由于水分堵塞了扩散途径，导致二氧化碳扩散阻力增加，净光合作用（NP）严重下降。然而，土壤地衣藓生双盘衣却没有出现这种下降，即使在藻体含水量最高时，NP也接近最大值。我们研究了皮层和髓层中的地衣物质（松萝酸和双盘衣酸）是否有助于维持高NP的能力。将干燥的藻体用无水丙酮提取，处理后发现它们在重新种植到田间后仍能完全存活并继续生长。正常藻体和提取后的藻体在NP对藻体含水量的响应上没有差异，实际上响应曲线往往几乎相同。因此，在这个物种中，地衣物质似乎并没有维持无水扩散途径，需要寻找其他解释，可能是结构方面的。
