Hu Yanping, Zhang Huixuan, Qian Qian, Lin Gonghua, Wang Jun, Sun Jing, Li Yi, Jang Jyan-Chyun, Li Wenjing
Qinghai Provincial Key Laboratory of Qinghai-Tibet Plateau Biological Resources, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Plants (Basel). 2022 Feb 14;11(4):512. doi: 10.3390/plants11040512.
Leaves are essential plant organs with numerous variations in shape and size. The leaf size is generally smaller in plants that thrive in areas of higher elevation and lower annual mean temperature. The Qinghai-Tibetan Plateau is situated at an altitude of >4000 m with relatively low annual average temperatures. Most plant species found on the Qinghai-Tibetan Plateau have small leaves, with Maxim. ex Balf. being an exception. Here, we show that the large leaves of with a unique three-dimensional (3D) shape are potentially an ideal solution for thermoregulation with little energy consumption. With the increase in age, the shape of leaves changed from a small oval plane to a large palmatipartite 3D shape. Therefore, is a highly heteroblastic species. The leaf shape change during the transition from the juvenile to the adult phase of the development in is a striking example of the manifestation of plant phenotypic plasticity. The temperature variation in different parts of the leaf was a distinct character of leaves of over-5-year-old plants. The temperature of single-plane leaves under strong solar radiation could accumulate heat rapidly and resulted in temperatures much higher than the ambient temperature. However, leaves of over-5-year-old plants could lower leaf temperature by avoiding direct exposure to solar radiation and promoting local airflow to prevent serious tissue damage by sunburn. Furthermore, the net photosynthesis rate was correlated with the heterogeneity of the leaf surface temperature. Our results demonstrate that the robust 3D shape of the leaf is a strategy that has developed evolutionarily to adapt to the strong solar radiation and low temperature on the Qinghai-Tibetan Plateau.
叶片是植物的重要器官，其形状和大小具有多种变化。在海拔较高、年平均温度较低的地区生长的植物，叶片通常较小。青藏高原海拔超过4000米，年平均温度相对较低。在青藏高原发现的大多数植物物种叶片较小，而Maxim. ex Balf.是个例外。在这里，我们表明，具有独特三维（3D）形状的大叶片可能是一种能耗低的理想温度调节解决方案。随着年龄的增长，Maxim. ex Balf.叶片的形状从小椭圆形平面变为大掌状深裂的3D形状。因此，Maxim. ex Balf.是一种高度异形叶的物种。Maxim. ex Balf.在发育从幼年阶段向成年阶段转变过程中的叶片形状变化，是植物表型可塑性表现的一个显著例子。5年以上植株叶片不同部位的温度变化是其叶片的一个明显特征。在强烈太阳辐射下，单平面叶片的温度会迅速积累热量，导致温度远高于环境温度。然而，5年以上植株的叶片可以通过避免直接暴露在太阳辐射下并促进局部气流来降低叶片温度，以防止晒伤造成严重的组织损伤。此外，净光合速率与叶片表面温度的异质性相关。我们的结果表明，叶片健壮的3D形状是Maxim. ex Balf.在进化过程中形成的一种策略，以适应青藏高原强烈的太阳辐射和低温。
