Balaguer L, Manrique E, de Los Rios A, Ascaso C, Palmqvist K, Fordham M, Barnes J D
Departamento de Biología Vegetal I, Facultad de Biología, Universidad Complutense, Madrid, E-28040, Spain e-mail:
Departamento de Biología Vegetal II, Facultad de Farmacia, Universidad Complutense, Madrid, E-28040, Spain, , , , , , ES.
Oecologia. 1999 May;119(2):166-174. doi: 10.1007/s004420050773.
Acclimation to elevated CO was investigated in Parmelia caperata originating from the vicinity of a natural CO spring, where the average daytime CO concentration was 729 ± 39 μmol mol dry air. Thalli showed no evidence of a down-regulation in photosynthetic capacity following long-term exposure to CO enrichment in the field; carboxylation efficiency, total Ribulose bisphosphate carboxylase/oxygenase (Rubisco) content, apparent quantum yield of CO assimilation, and the light-saturated rate of CO assimilation (measured under ambient and saturating CO concentrations) were similar in thalli from the naturally CO enriched site and an adjacent control site where the average long-term CO concentration was about 355 μmol mol. Thalli from both CO environments exhibited low CO compensation points and early saturation of CO uptake kinetics in response to increasing external CO concentrations, suggesting the presence of an active carbon-concentrating mechanism. Consistent with the lack of significant effects on photosynthetic metabolism, no changes were found in the nitrogen content of thalli following prolonged exposure to elevated CO. Detailed intrathalline analysis revealed a decreased investment of nitrogen in Rubisco in the pyrenoid of algae located in the elongation zone of thalli originating from elevated CO, an effect associated with a reduction in the percentage of the cell volume occupied by lipid bodies and starch grains. Although these differences did not affect the photosynthetic capacity of thalli, there was evidence of enhanced limitations to CO assimilation in lichens originating from the CO-enriched site. The light-saturated rate of CO assimilation measured at the average growth CO concentration was found to be significantly lower in thalli originating from a CO-enriched atmosphere compared with that of thalli originating and measured at ambient CO. At lower photosynthetic photon flux densities, the light compensation point of net CO assimilation was significantly higher in thalli originating from elevated CO, and this effect was associated with higher usnic acid content.
对源自天然一氧化碳泉附近的石耳进行了对高浓度一氧化碳适应情况的研究，该区域白天一氧化碳平均浓度为729±39μmol/mol干空气。在野外长期暴露于一氧化碳富集环境后，地衣体未表现出光合能力下调的迹象；来自天然一氧化碳富集地和相邻对照地（平均长期一氧化碳浓度约为355μmol/mol）的地衣体，其羧化效率、总核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco）含量、一氧化碳同化的表观量子产率以及一氧化碳同化的光饱和速率（在环境和饱和一氧化碳浓度下测量）相似。来自这两种一氧化碳环境的地衣体均表现出低一氧化碳补偿点以及随着外部一氧化碳浓度增加一氧化碳吸收动力学的早期饱和，表明存在活跃的碳浓缩机制。与对光合代谢无显著影响一致，长期暴露于高浓度一氧化碳后，地衣体的氮含量未发生变化。详细的地衣体内分析表明，来自高浓度一氧化碳环境的地衣体伸长区藻类的类囊体中，Rubisco的氮投入减少，这种效应与脂质体和淀粉粒所占细胞体积百分比的降低有关。尽管这些差异未影响地衣体的光合能力，但有证据表明来自一氧化碳富集地的地衣中一氧化碳同化的限制增强。发现在平均生长一氧化碳浓度下测量的一氧化碳同化光饱和速率，来自一氧化碳富集大气的地衣体显著低于来自环境一氧化碳浓度并在该浓度下测量的地衣体。在较低的光合光子通量密度下，来自高浓度一氧化碳环境的地衣体净一氧化碳同化的光补偿点显著更高，且这种效应与更高的扁枝衣酸含量有关。
