Hashim Ahmed M, Alharbi Basmah M, Abdulmajeed Awatif M, Elkelish Amr, Hozzein Wael N, Hassan Heba M
Botany Department, Faculty of Science, Ain Shams University, Cairo 11865, Egypt.
Biology Department, Faculty of Science, Tabuk University, Tabuk 71421, Saudi Arabia.
Plants (Basel). 2020 Jul 9;9(7):869. doi: 10.3390/plants9070869.
Most endemic plant species have limited altitudinal ranges. At higher altitudes, they are subjected to various environmental stresses. However, these plants use unique defense mechanisms at high altitudes as a convenient survival strategy. The changes in antioxidant defense system and accumulation of different secondary metabolites (SMs) were investigated as depending on altitude in five endemic endangered species (, subsp. , , , and ) naturally growing in Saint Katherine protectorate (SKP). Leaves were collected from different sites between 1600 and 2200 m above sea level to assess the biochemical and physiological variations in response to high altitudes. At higher altitudes, the soil pH and micronutrient soil content decreased, which can be attributed to lower mineralization processes at lower pH. Total phenols, ascorbic acid, proline, flavonoids, and tannins increased in response to different altitudes. SMs progressively increased in the studied species, associated with a significant decrease in the levels of antioxidant enzyme activity. as the most threatened plant, showed the maximum response compared with other species. There was an increase in photosynthetic pigments, which was attained via the increase in chlorophyll a, chlorophyll b, and carotenoid contents. There was a significant increase in total soluble sugars and total soluble protein content in response to different altitudes. SDS-PAGE of leaf proteins showed alteration in the protein profile between different species and the same species grown at a different altitude. These five species can adapt to high-altitude habitats by various physiological mechanisms, which can provide a theoretical basis for the future conservation of these endangered endemic species in SKP.
大多数特有植物物种的海拔分布范围有限。在较高海拔地区，它们会受到各种环境压力。然而，这些植物在高海拔地区利用独特的防御机制作为一种便捷的生存策略。研究了圣凯瑟琳保护区（SKP）自然生长的五种特有濒危物种（、亚种、、和）中抗氧化防御系统的变化以及不同次生代谢产物（SMs）的积累与海拔的关系。从海拔1600米至2200米的不同地点采集叶片，以评估对高海拔的生化和生理变化响应。在较高海拔地区，土壤pH值和微量营养元素土壤含量下降，这可归因于较低pH值下较低的矿化过程。总酚、抗坏血酸、脯氨酸、类黄酮和单宁随海拔变化而增加。所研究物种中的SMs逐渐增加，同时抗氧化酶活性水平显著下降。作为最受威胁的植物，与其他物种相比表现出最大的响应。光合色素增加，这是通过叶绿素a、叶绿素b和类胡萝卜素含量的增加实现的。总可溶性糖和总可溶性蛋白质含量随海拔变化而显著增加。叶片蛋白质的SDS-PAGE显示不同物种之间以及同一物种在不同海拔生长时蛋白质谱的变化。这五个物种可以通过各种生理机制适应高海拔栖息地，这可为未来SKP中这些濒危特有物种的保护提供理论依据。
