Guizhou Botanical Garden, Guiyang, 550001, China.
Guizhou Academy of Forestry Sciences, Guiyang, 550005, China.
BMC Plant Biol. 2023 Mar 25;23(1):160. doi: 10.1186/s12870-022-03980-4.
Lithophytic bryophytes grow on the rock surface, change the habitat on the rock surface through biological karstification, and provide a material basis for the growth of other plants. However, the surface calcium content of bare rock is high. The lithophytic bryophytes may have a special mechanism to adapt to the karst high calcium environment. The present study aimed to explore the physiological regulation process of karst lithophytic bryophytes under high calcium environment, and to provide scientific basis for revealing the maintenance mechanism of karst biodiversity.
With the increase of Ca concentration, the contents of Pro, SP and MDA of lithophytic bryophytes showed a downward-upward-downward trend. However, when Ca ≥ 400 mmol/L, the contents of Pro and SP changed significantly at 1d, 2d, 3d, 5d and 7d with the extension of culture time, and lithophytic bryophytes died after 2 months of culture. Under different Ca concentrations, the maximum SOD activity of lithophytic bryophytes is 1758.00 (U/g FW), the minimum is 92.60 (U/g FW), the maximum POD activity is 120.88 (U/g FW), and the minimum is 4.80 (U/g FW). The antioxidative activity of of Hyophila involuta are higher than that of Didymodon constrictus and Eurohypnum leptothallum, and its enzyme activity changed significantly with the increase of calcium concentration and time.At the same time, the contents of TChl, Chla, and Chlb in lithophytic bryophytes decreased with the increase of Ca concentration. When Ca = 400 mmol/L, the contents of TChl and Chla were the lowest, but when Ca > 400 mmol/L, they began to increase. In addition, ABA is negatively correlated with TChl and Chla, and positively correlated with ROS. It shows that ABA has a certain role in regulating the adaptation of lithophytic bryophytes to high calcium environment.
Lithophytic bryophytes have strong calcium tolerance, and their physiological response to high calcium stress is different from vascular bundle plants. The general stress principle is not applicable to lithophytic bryophytes. The response of lithophytic bryophytes to the change of Caconcentration is slow, showing passive response or inert response.
石生植物生长在岩石表面，通过生物岩溶作用改变岩石表面的生境，为其他植物的生长提供物质基础。但是，裸岩表面的钙含量较高。石生植物可能具有一种特殊的机制来适应岩溶高钙环境。本研究旨在探讨高钙环境下石生苔藓植物的生理调节过程，为揭示岩溶生物多样性维持机制提供科学依据。
随着 Ca 浓度的增加，石生苔藓植物 Pro、SP 和 MDA 的含量呈先下降后上升再下降的趋势。然而，当 Ca≥400mmol/L 时，培养时间延长至 1d、2d、3d、5d 和 7d 时，Pro 和 SP 的含量变化明显，培养 2 个月后苔藓植物死亡。在不同 Ca 浓度下，石生苔藓植物的最大 SOD 活性为 1758.00（U/g FW），最小为 92.60（U/g FW），最大 POD 活性为 120.88（U/g FW），最小为 4.80（U/g FW）。厚叶拟鳞叶苔的抗氧化活性高于粗叶短月藓和东亚砂藓，其酶活性随 Ca 浓度和时间的增加而显著变化。同时，石生苔藓植物的总叶绿素（TChl）、叶绿素 a（Chla）和叶绿素 b（Chlb）含量随 Ca 浓度的增加而降低。当 Ca=400mmol/L 时，TChl 和 Chla 的含量最低，但当 Ca＞400mmol/L 时，它们开始增加。此外，ABA 与 TChl 和 Chla 呈负相关，与 ROS 呈正相关。这表明 ABA 在调节石生苔藓植物对高钙环境的适应中具有一定的作用。
石生苔藓植物具有较强的耐钙能力，其对高钙胁迫的生理响应不同于维管束植物。一般的胁迫原则不适用于石生苔藓植物。石生苔藓植物对 Ca 浓度变化的反应较慢，表现为被动反应或惰性反应。
