Institute of Agriculture and Life Science (IALS), Gyeongsang National University, Jinju, Republic of Korea.
Division of Applied Life Science (BK21), Gyeongsang National University, Jinju, Republic of Korea.
Plant Signal Behav. 2023 Dec 31;18(1):2245625. doi: 10.1080/15592324.2023.2245625.
In tropical forests, the shade provided by tree canopies and extreme climate causes inhibition of plant seedling growth due to the lack of light. However, the plants can acclimate to such environmental stress by generating specific responses. The present study aimed to investigate the effects of shading conditions on ecophysiological performance of Narra seedlings ( L.) via a mesocosm experiment. A pot experiment was conducted for 20 weeks in a greenhouse with different shading treatments, 75% (control), 25%, and 4% of full sunlight (FS). As a result, the photosynthetic rate (), Rubisco enzyme activity, maximum carboxylation rate (), and maximum electron transport rate () in 25% FS treatment were higher or similar to those in control after three weeks of the beginning of shade treatment, whereas the highest values after ten weeks were observed in control. In contrast, the photosynthetic pigments were highest in control after three weeks, while the values were highest in 25% FS treatment after ten weeks. The growth parameters, such as biomass and leaf area, were highest in 75% FS treatment. The expression of Rubisco, phosphoglycerate kinase, glyceraldehyde-3-phosphate dehydrogenase, and fructose-1,6-bisphosphatase were up-regulated in 4% FS treatment compared to control after ten weeks, contributing to tolerating the shade stress. Our findings indicated the capacity of seedlings to tolerate and acclimate low light conditions causing shade stress by generating specific physiological and morphological responses, especially Rubisco enzyme activity as well as gene expression related to photosynthetic activity. The present study will improve our understanding of the tolerance mechanism of Narra plant under light-deficient conditions, thereby providing a better strategy for efficiently growing seedlings of this species in tropical rainforests.
在热带森林中，树冠提供的阴凉和极端气候导致光照缺乏，从而抑制了植物幼苗的生长。然而，植物可以通过产生特定的反应来适应这种环境胁迫。本研究旨在通过一个中观实验来研究遮荫条件对南洋楹（ L.）幼苗生态生理性能的影响。在一个带有不同遮荫处理（75%（对照）、25%和 4%的全光照（FS））的温室中进行了为期 20 周的盆栽实验。结果表明，在遮荫处理开始后的三周内，25% FS 处理的光合速率（）、Rubisco 酶活性、最大羧化率（）和最大电子传递率（）高于或与对照相似，而在十周后则达到最高值。相比之下，在三周后对照的光合色素最高，而在十周后 25% FS 处理的光合色素最高。在 75% FS 处理中，生物量和叶面积等生长参数最高。与对照相比，Rubisco、磷酸甘油酸激酶、甘油醛-3-磷酸脱氢酶和果糖-1,6-二磷酸酶的表达在十周后在 4% FS 处理中上调，有助于耐受遮荫胁迫。我们的研究结果表明，南洋楹幼苗具有耐受和适应由遮荫引起的低光照条件的能力，特别是通过产生 Rubisco 酶活性以及与光合作用相关的基因表达来产生特定的生理和形态反应。本研究将提高我们对光缺乏条件下南洋楹植物耐受机制的理解，从而为在热带雨林中高效培育该物种的幼苗提供更好的策略。
