Cyanolichens are symbiotic organisms involving cyanobacteria and fungi (bipartite) or with the addition of an algal partner (tripartite). Cyanolichens are known for their heightened susceptibility to environmental pollution. We focus here on the impacts on cyanolichens due to rising air pollution; we are especially interested in the role of sulfur dioxide on cyanolichen biology. Cyanolichens due to air pollution including sulfur dioxide exposure, show symptomatic changes including degradation of chlorophyll, lipid membrane peroxidation, decrease in ATP production, changes in respiration rate, and alteration of endogenous auxins and ethylene production, although symptoms are known to vary with species and genotype. Sulfur dioxide has been shown to be damaging to photosynthesis but is relatively benign on nitrogen fixation which proposes as a hypothesis that the algal partner may be more in harm’s way than the cyanobiont. In fact, the Nostoc cyanobiont of sulfur dioxide-susceptible Lobaria pulmonaria carries a magnified set of sulfur (alkane sulfonate) metabolism genes capable of alkane sulfonate transport and assimilation, which were only unraveled by genome sequencing, a technology unavailable in the 1950–2000 epoch, where most physiology- based studies were performed. There is worldwide a growing corpus of evidence that sulfur has an important role to play in biological symbioses including rhizobia-legumes, mycorrhizae-roots and cyanobacteria-host plants. Furthermore, the fungal and algal partners of L. pulmonaria appear not to have the sulfonate transporter genes again providing the roles of ambient-sulfur (alkanesulfonate metabolism etc.) mediated functions primarily to the cyanobacterial partner. In conclusion, we have addressed here the role of the atmospheric pollutant sulfur dioxide to tripartite cyanolichen viability and suggest that the weaker link is likely to be the photosynthetic algal (chlorophyte) partner and not the nitrogen-fixing cyanobiont.

蓝藻是涉及蓝藻和真菌（二方）或添加藻类伙伴（三方）的共生生物。氰化物以其对环境污染的高度敏感性而闻名。我们在此关注空气污染加剧对氰基地衣的影响；我们对二氧化硫对氰地衣生物的作用特别感兴趣。由于空气污染（包括二氧化硫暴露）而导致的氰化物表现出症状变化，包括叶绿素降解、脂质膜过氧化、ATP 产生减少、呼吸速率变化以及内源生长素和乙烯产生的改变，尽管已知症状因物种和种类而异。基因型。二氧化硫已被证明会损害光合作用，但对固氮作用相对温和，这提出了一个假设，即藻类伙伴可能比蓝藻生物更容易受到伤害。事实上，对二氧化硫敏感的肺叶发菜携带一组放大的硫（烷磺酸盐）代谢基因，能够进行烷磺酸盐运输和同化，这些基因只有通过基因组测序才能解开，而基因组测序在 1950-2000 年时期是不可用的。 ，大多数基于生理学的研究都是在那里进行的。世界范围内越来越多的证据表明，硫在生物共生中发挥着重要作用，包括根瘤菌-豆科植物、菌根-根和蓝藻-宿主植物。此外，肺乳杆菌的真菌和藻类伙伴似乎不具有磺酸盐转运蛋白基因，而磺酸盐转运蛋白基因主要为蓝藻伙伴提供环境硫（烷磺酸盐代谢等）介导的功能。总之，我们在这里讨论了大气污染物二氧化硫对三方氰地衣生存能力的作用，并表明较弱的环节可能是光合藻类（叶绿素）伙伴，而不是固氮氰化生物。