沙冬青叶片中 C31 烷烃的大量增加有助于其对非生物胁迫的极强耐受性。
Massive increases in C31 alkane on Zygophyllum xanthoxylum leaves contribute to its excellent abiotic stress tolerance.
机构信息
State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, PR China.
Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, ON K1S 5B6, Canada.
出版信息
Ann Bot. 2023 Apr 28;131(4):723-736. doi: 10.1093/aob/mcad038.
BACKGROUND AND AIMS
Desert plants possess excellent water-conservation capacities to survive in extreme environments. Cuticular wax plays a pivotal role in reducing water loss through plant aerial surfaces. However, the role of cuticular wax in water retention by desert plants is poorly understood.
METHODS
We investigated leaf epidermal morphology and wax composition of five desert shrubs from north-west China and characterized the wax morphology and composition for the typical xerophyte Zygophyllum xanthoxylum under salt, drought and heat treatments. Moreover, we examined leaf water loss and chlorophyll leaching of Z. xanthoxylum and analysed their relationships with wax composition under the above treatments.
KEY RESULTS
The leaf epidermis of Z. xanthoxylum was densely covered by cuticular wax, whereas the other four desert shrubs had trichomes or cuticular folds in addition to cuticular wax. The total amount of cuticular wax on leaves of Z. xanthoxylum and Ammopiptanthus mongolicus was significantly higher than that of the other three shrubs. Strikingly, C31 alkane, the most abundant component, composed >71 % of total alkanes in Z. xanthoxylum, which was higher than for the other four shrubs studied here. Salt, drought and heat treatments resulted in significant increases in the amount of cuticular wax. Of these treatments, the combined drought plus 45 °C treatment led to the largest increase (107 %) in the total amount of cuticular wax, attributable primarily to an increase of 122 % in C31 alkane. Moreover, the proportion of C31 alkane within total alkanes remained >75 % in all the above treatments. Notably, the water loss and chlorophyll leaching were reduced, which was negatively correlated with C31 alkane content.
CONCLUSION
Zygophyllum xanthoxylum could serve as a model desert plant for study of the function of cuticular wax in water retention because of its relatively uncomplicated leaf surface and because it accumulates C31 alkane massively to reduce cuticular permeability and resist abiotic stressors.
背景与目的
沙漠植物具有出色的节水能力，以在极端环境中生存。角质层蜡在通过植物气生表面减少水分流失方面起着关键作用。然而，角质层蜡在沙漠植物保水方面的作用还知之甚少。
方法
我们研究了来自中国西北的 5 种沙漠灌木的叶片表皮形态和蜡质组成，并对典型的旱生植物四合木（Zygophyllum xanthoxylum）在盐、干旱和热胁迫下的蜡质形态和组成进行了特征描述。此外，我们还检测了四合木的叶片水分损失和叶绿素浸出，并在上述处理下分析了它们与蜡质组成的关系。
主要结果
四合木的叶片表皮被角质层蜡紧密覆盖，而其他 4 种沙漠灌木除了角质层蜡之外还有毛或角质褶皱。四合木和白刺（Ammopiptanthus mongolicus）叶片上的总蜡量明显高于其他 3 种灌木。引人注目的是，C31 烷烃是最丰富的成分，占四合木总烷烃的>71%，高于本研究中其他 4 种灌木。盐、干旱和热胁迫导致角质层蜡的量显著增加。在这些处理中，干旱加 45°C 的联合处理导致总角质层蜡量增加最大（107%），主要归因于 C31 烷烃增加了 122%。此外，在所有上述处理中，C31 烷烃在总烷烃中的比例仍保持在>75%。值得注意的是，水分损失和叶绿素浸出减少，这与 C31 烷烃含量呈负相关。
结论
由于四合木叶片表面相对简单，并且大量积累 C31 烷烃以降低角质层通透性并抵抗非生物胁迫，因此可将其作为研究角质层蜡在保水方面功能的典型沙漠植物模型。
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