Shenzhen Key Laboratory of Marine Bio-resource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, 518071, Shenzhen, China; College of Physics and Optoelectronic Engineering, Shenzhen University, 518060, Shenzhen, China; Greater Bay Area Mangrove Wetland Research & Development Centre, Guangdong Neilingding Futian National Nature Reserve, 518040, Shenzhen, China.
Greater Bay Area Mangrove Wetland Research & Development Centre, Guangdong Neilingding Futian National Nature Reserve, 518040, Shenzhen, China; College of Fisheries, Jimei University, 361021, Xiamen, China.
Mar Environ Res. 2022 Apr;176:105611. doi: 10.1016/j.marenvres.2022.105611. Epub 2022 Mar 18.
Laguncularia racemosa (a white mangrove) is an exotic mangrove species commonly distributed in southern intertidal zones in China since it was introduced for reforestation purposes in 1999. However, the invasiveness of this exotic species and its cold adaptability have rarely been reported. The present work determined the cold resistance level of L. racemosa and its recovery from cold stress, aiming to speculate its potential invasive capability in China. Results showed that the germination of L. racemosa seeds in sand or in simulated sea field models was significantly inhibited by a series of cold treatments, with no germination at 5 °C and decreased in germination at low temperatures (15-25 °C). Low temperature also reduced net photosynthetic rate (A), water use efficiency (WUE), transpiration rate (E), and stomatal conductance (Gs) of the seedlings of L. racemosa. On the other hand, cold stress up-regulated in leaves of malondialdehyde (MDA) and antioxidant activities, including superoxide dismutase (SOD), glutathione reductase (GR), and ascorbate peroxidase (APX). Additionally, these physiological and biochemical indexes of cold-stressed L. racemosa could recover to the original levels if the plants were returned to room temperature with a few exceptions. For instance, the cold exposure duration altered seedlings' physiology, but the photosynthetic related activities could not recover if cold treatment lasted for 120 h. This study suggests that L. racemosa can tolerate low temperatures to some extent, thus settle and even invade the coast of China at high latitudes having cold winter, which poses a challenge to the conservation and management of local mangrove ecosystems.
拉关木（一种红树植物）是一种外来的红树林物种，自 1999 年被引入用于造林以来，在中国南部的潮间带广泛分布。然而，该外来物种的入侵性及其耐寒性很少有报道。本研究旨在确定拉关木的耐寒水平及其对冷胁迫的恢复能力，以推测其在中国潜在的入侵能力。结果表明，拉关木种子在沙或模拟海况模型中的萌发受到一系列低温处理的显著抑制，在 5℃时无萌发，在低温（15-25℃）下萌发减少。低温还降低了拉关木幼苗的净光合速率（A）、水分利用效率（WUE）、蒸腾速率（E）和气孔导度（Gs）。另一方面，冷胁迫会导致叶片中超氧化物歧化酶（SOD）、谷胱甘肽还原酶（GR）和抗坏血酸过氧化物酶（APX）等抗氧化活性物质的丙二醛（MDA）含量增加。此外，如果将植物恢复到室温，拉关木受冷胁迫的这些生理和生化指标除了极少数例外，都可以恢复到原始水平。例如，冷暴露时间改变了幼苗的生理机能，但如果冷处理持续 120 小时，与光合作用相关的活性就无法恢复。本研究表明，拉关木在一定程度上可以耐受低温，因此可以在冬季寒冷的高纬度地区定居甚至入侵中国沿海地区，这对当地红树林生态系统的保护和管理构成了挑战。
