College of Life Science, Henan Normal University, Xinxiang, Henan 453007, China.
College of Life Science, Henan Normal University, Xinxiang, Henan 453007, China; and Engineering Technology Research Center of Nursing and Utilisation of Genuine Chinese Crude Drugs in Henan Province, Xinxiang, Henan 453007, China; and Corresponding author. Email:
Funct Plant Biol. 2021 Aug;48(9):851-859. doi: 10.1071/FP20274.
Plants inevitably receive harmful UV-B radiation when exposed to solar energy, so they have developed a variety of strategies to protect against UV-B radiation damage during long-term evolution. In this study, Zebrina pendulaSchnizl. was used to investigate the plant defence against UV-B radiation because of its strong adaptability to sunlight changes, and the colour of its leaves changes significantly under different sunlight intensities. The experiment was carried out to study the changes of Z. pendula leaves under three light conditions: artificial daylight (control check); shading 50%; and artificial daylight + UV-B, aiming to explore the mechanism of defence against UV-B radiation by observing changes in leaf morphological structure, anthocyanin content and distribution. Results showed that the single leaf area increased but leaves became thinner, and the anthocyanin content in the epidermal cells decreased under 50% shading. In contrast, under daylight + UV-B, the single leaf area decreased but thickness increased (mainly due to the increase of the thickness of the upper epidermis and the palisade tissue), the trichomes increased. In addition, the anthocyanin content in the epidermal cells and phenylalanine ammonia-lyase (PAL) activity increased, and the leaf colour became redder, also, the photosynthetic pigment content in mesophyll cells and the biomass per unit volume increased significantly under daylight + UV-B. Thus, when UV-B radiation was enhanced, Z. pendula leaves reduced the exposure to UV-B radiation by reducing the area, and reflect some UV-B radiation by growing trichomes. The UV-B transmittance was effectively reduced by increasing the single leaf thickness and anthocyanin content to block or absorb partial UV-B. Through the above comprehensive defence strategies, Z. pendula effectively avoided the damage of UV-B radiation to mesophyll tissue.
植物在接受太阳能时不可避免地会受到有害的 UV-B 辐射，因此它们在长期进化过程中发展了多种策略来保护免受 UV-B 辐射的伤害。在这项研究中，由于其对阳光变化的强适应性以及在不同阳光强度下叶片颜色变化显著，因此使用了 Zebrina pendula Schnizl. 来研究植物对 UV-B 辐射的防御机制。实验是在三种光照条件下进行的，以研究 Z. pendula 叶片的变化：人工日光（对照检查）；遮荫 50%；和人工日光+UV-B，旨在通过观察叶片形态结构、花青素含量和分布的变化来探索防御 UV-B 辐射的机制。结果表明，在 50%遮荫下，单叶面积增加但叶片变薄，表皮细胞中的花青素含量减少。相比之下，在日光+UV-B 下，单叶面积减小但厚度增加（主要是由于上表皮和栅栏组织厚度增加），毛状体增加。此外，表皮细胞中的花青素含量和苯丙氨酸解氨酶（PAL）活性增加，叶片颜色变红，并且在日光+UV-B 下，叶肉细胞中的光合色素含量和单位体积的生物量显著增加。因此，当 UV-B 辐射增强时，Z. pendula 叶片通过减少面积来减少暴露于 UV-B 辐射的程度，并通过生长毛状体来反射一些 UV-B 辐射。通过增加单叶厚度和花青素含量来有效降低 UV-B 透过率，从而阻挡或吸收部分 UV-B。通过上述综合防御策略，Z. pendula 有效地避免了 UV-B 辐射对叶肉组织的伤害。
