Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna, 38200 La Laguna, Canary Islands, Spain.
J Exp Bot. 2022 Jul 16;73(13):4562-4575. doi: 10.1093/jxb/erac104.
The data available so far indicate that the photosynthetic and relative growth rates of bryophytes are 10% of those reported for tracheophytes. By examining the existing literature and reanalysing data published in over 100 studies, this review examines the ecophysiological, biochemical, and structural reasons behind this phenomenon. The limiting Rubisco content and surface for gas exchange are the internal factors that can explain the low photosynthetic and growth rates of bryophytes. The role of the thicker cell walls of bryophytes in limiting CO2 diffusion is unclear, due to the current uncertainties regarding their porosity and permeability to CO2. From this review, it is also evident that, despite bryophytes having low photosynthetic rates, their positive carbon balance is tightly related to their capacity to deal with extreme conditions. Contributing factors include their capacity to deal with large daily temperature oscillations, and their capacity to delay the cessation of photosynthesis under water deficit (or to tolerate desiccation in extreme situations). Although further studies on bryophytes are needed before more solid conclusions can be drawn, it seems that their success relies on their remarkable tolerance to a highly variable environment, possibly at the expense of their maximum photosynthetic rate.
目前可用的数据表明，苔藓植物的光合和相对生长速率仅为维管束植物的 10%。本综述通过检查现有文献并重新分析了 100 多项研究中发表的数据，探讨了造成这种现象的生理生态、生化和结构原因。限制 Rubisco 含量和气体交换表面的是内部因素，这些因素可以解释苔藓植物光合作用和生长速率低的原因。由于目前对苔藓植物的孔隙度和 CO2 透过性存在不确定性，因此它们较厚的细胞壁在限制 CO2 扩散方面的作用尚不清楚。从本综述还可以明显看出，尽管苔藓植物的光合速率较低，但它们的正碳平衡与其应对极端条件的能力密切相关。促成因素包括它们处理较大的日温度波动的能力，以及在水分亏缺下延迟光合作用停止的能力（或在极端情况下耐受干燥）。尽管在得出更可靠的结论之前还需要对苔藓植物进行进一步研究，但似乎它们的成功依赖于其对高度可变环境的显著耐受性，这可能是以牺牲最大光合速率为代价的。
