【作者】 刘璐；

【导师】 樊大勇；

【作者基本信息】 北京林业大学 ， 林业硕士（专业学位）， 2024， 硕士

【摘要】 在新时代城市园林绿化的规划与设计过程中,彩叶树种由于其独特的叶片色彩得到了广泛的应用。彩叶植物叶片富含花色苷、类黄酮等非光合作用色素,其生理生态功能目前还没有明确结论。本研究选择了北京常见园林绿化树种,李属红叶的紫叶李（Prunus cerasifera）和美人梅（Prunus×blireana）,绿叶的榆叶梅（Prunus triloba）、樱桃（Prunus pseudocerasus）、杏梅（Prunus mume）,女贞属黄叶的金叶女贞（Ligustrum×vicaryi）和绿叶的小叶女贞（Ligustrum quihoui）作为研究材料。这些植物均生长在国家植物园,全光照自然生长条件下。连续两年于生长季（6-8月）,采用自研发的无损快速检测技术（P700⁺氧化还原动力学面积法）测定强光下这些植物的功能性光系统II（PSⅡ）相对含量和光系统I（PSⅠ）相对含量的变化（在没有修复的情况下）,获得紫叶李、榆叶梅、金叶女贞、小叶女贞在蓝光和红光下的抗光抑制能力,同时测定了其光合参数和气孔导度,采用荧光影像技术测定了光化学量子效率等指标;在以上研究基础上,进一步研究了太阳光照条件下紫叶李、美人梅、榆叶梅、樱桃和杏梅的抗光抑制能力及其温度响应曲线（在没有修复的情况下）。对于7种彩叶树种及其同属绿叶植物使用积分球测定了叶片的光吸收光谱,使用分光光度计测定了光合及非光合色素含量。还测量了叶片的解剖结构和叶片横截面的叶绿素荧光分布。主要研究结果如下:（1）红叶（紫叶李）的花色苷含量是绿叶（榆叶梅）的13倍以上。红叶（紫叶李）与绿叶（榆叶梅）在红光下的PSⅡ光化学最大量子效率（F_v/F_m）和表观二氧化碳量子产率（AQY）没有差异,但红叶（紫叶李）表现出一些阴生适应性特征,包括较低的Chl a/b比值、较低的光合速率、较低的气孔导度和较低的PSⅡ/PSⅠ比值（相对值）。（2）在没有修复的情况下,红叶（紫叶李）在红光下的PSⅡ光失活速率系数（k_i）是绿叶（榆叶梅）的1.8倍,但在蓝光下则明显较低（-18%）。简化的色素双层模型分析结果表明,花色苷主要起到了消减光的作用从而提高了在蓝光下的光保护能力。（3）与红叶不同,相比于同属绿色叶片,生长季的金叶女贞黄叶的类黄酮含量无显著差异而光合色素含量及花色苷含量极低且光合速率极低。其生理生态功能可能是树冠外层叶片对于光的过滤从而保护内层绿色叶片使其光合功能完整。（4）太阳光照下25℃时,对于五种李属树种,红叶（紫叶李、美人梅）的强光敏感性(m_pi)（没有修复的情况下）低于绿叶（榆叶梅、樱桃、杏梅）,说明红叶太阳光下抵抗光抑制能力更强。但含花色苷量较高的红叶（紫叶李和美人梅）温度敏感性低,抵抗高温（>37.5℃）光抑制的能力不如绿叶树种（榆叶梅、樱桃、杏梅）。显然,太阳光下花色苷含量对植物抵抗光抑制能力有着积极影响,但仍需综合考虑其它环境因素的联合作用。（5）彩叶树种和绿叶树种的叶片结构及色素分布存在差异,红叶树种（紫叶李、美人梅）叶片下表皮厚度厚于绿叶树种（榆叶梅、樱桃、杏梅）。红叶树种的花色苷主要分布在上表皮和栅栏组织中。叶片内叶绿素荧光强度分布分析结果表明红叶和黄叶（金叶女贞）树种的叶绿素主要分布在栅栏组织中,而绿叶树种的叶绿素分布更为均匀。综上所述,本研究结果明确了花色苷对红色叶片的光保护机制,部分解决了长期以来关于花色苷光保护机制的争议。研究表明花色苷主要通过光衰减方式保护光系统II,而不是通过活性氧清除等其他方式。进一步的研究发现,在同属的5种李属树种之间,太阳光下红叶树种抵抗光抑制能力更强（25℃）。但是光敏感性的温度响应曲线表明红叶树种在高温下抵抗光抑制能力弱于绿叶树种。生长季黄叶生理生态功能并不是主要进行光合作用,而是通过过滤光的形式保护冠层内部叶片的光合功能。彩叶植物叶片内部叶绿素含量分布与绿叶植物不同,可能在抵抗光抑制能力和碳同化能力等方面起到了独特作用。本研究为进一步探讨生长季红叶中的花色苷和黄叶中类黄酮的生理生态功能提供了研究方向。同时,也为城市景观中彩叶植物的培育、配置及养护管理提供理论上的指导和参考。更多还原

【Abstract】 Because of their special leaf color,colored foliage species have been used more and more comprehensively in the planning and design of urban landscaping in cities.The leaves of colorful foliage plants are rich in non-photosynthetic pigments such as anthocyanins and flavonoids,but their physiological and ecological functions have not yet been clearly revealled.We gathered common gardening tree species belonging to the same genus Prunus in Beijing for this paper,including red-leaved Prunus cerasifera and Prunus×blireana,green-leaved Prunus triloba,Prunus pseudocerasus and Prunus mume.Yellow-leafed Ligustrum×vicaryi and green-leaf Ligustrum quihoui,both of which belong to the genus Ligustrum,were employed as study materials.These plants were grown under natural full sunlight conditions at the National Botanical Garden.In two consecutive years during the growing season（June-August）,a self-developed nondestructive rapid detection technique（P700⁺redox kinetic area method）was used to determine the changes in the relative content of functional photosystem II（PSⅡ）and the relative content of photosystem I（PSⅠ）in these plants under strong light（without repair）,and to obtain the relative content of Prunus cerasifera,Prunus triloba,Ligustrum×vicaryi and Ligustrum quihoui in the presence of blue and red light,Additionally,photosynthetic parameters and stomatal conductance were measured.The photochemical quantum efficiency and other indexes were determined by fluorescence imaging technique.Based on the above research,further studies were conducted to investigate the resistance to photoinhibition and its temperature response curves（without repair）of Prunus cerasifera,Prunus×blireana,Prunus triloba,Prunus pseudocerasus and Prunus mume under solar radiation.For seven colourful tree species and their congeneric greens the light absorption spectra of the leaves were determined using an integrating sphere,the photosynthetic and non-photosynthetic pigment contents were determined using a spectrophotometer.The measurement of leaf anatomy and chlorophyll fluorescence distribution curves in leaf cross sections was done as well.The main findings are summarized below:（1）The content of anthocyanins in red leaves（Prunus cerasifera）was>13 times greater than that in green leaves（Prunus triloba）.With no difference in maximum quantum efficiency of PSⅡ photochemistry（F_v/F_m）and apparent CO₂ quantum yield（AQY）in red light,red leaves（Prunus cerasifera）showed some shade-acclimated suites,including lower Chl a/b ratio,lower photosynthesis rate,lower stomatal conductance and lower PSⅡ/PSⅠ ratio（on an arbitrary scale）,compared with green leaves（Prunus triloba）.（2）In the absence of repair of PSⅡ,red leaves（Prunus cerasifera）showed a rate coefficient of PSⅡ photoinactivation（k_i）that was 1.8 times higher than that of green leaves（Prunus triloba）under red light,but significantly lower（-18%）under blue light.Analysis using a simplified pigment bilayer model indicated that anthocyanins primarily function to attenuate light,thereby enhancing photoprotection under blue light.（3）Unlike red leaves,the yellow leaves of Ligustrum×vicaryi during the growing season exhibited no significant differences in flavonoid content compared to their green counterparts,but had extremely low photosynthetic pigment and anthocyanin contents,resulting in extremely low photosynthetic rates.The physiological and ecological aim of their leaves is to protect the photosynthetic function of the inner green leaves by filtering light from the outer canopy leaves.（4）Under solar radiation,the sensitivity to strong light(m_pi)at 25°C（without repair）was lower in red-leaved species（Prunus cerasifera and Prunus×blireana）compared to green-leaved species（Prunus triloba,Prunus pseudocerasus and Prunus mume）among the five Prunus species.This suggests that red leaves are more resistant to photoinhibition under solar radiation in the field.However,red-leaved species with higher anthocyanin content（Prunus cerasifera and Prunus×blireana）exhibited a lower temperature sensitivity and weaker resistance to photoinhibition at high temperatures（>37.5°C）compared to green-leaved species.Evidently,anthocyanin content positively affects the plant’s resistance to photoinhibition under solar radiation,but its effects must be considered in conjunction with other co-occurring environmental factors.（5）Leaf structure and pigment distribution are different between colored-leaf species and green-leaf species.The lower epidermal thickness of the red-leaved species（Prunus cerasifera and Prunus×blireana）is thicker than that of the green-leaved species.Anthocyanins in red-leaved species are mainly distributed in the upper epidermis and palisade tissue.Analysis of chlorophyll fluorescence intensity distribution within the leaves revealed that chlorophyll in red-leaved and yellow-leaved（Ligustrum×vicaryi）species is primarily located in the palisade tissue,while chlorophyll distribution is more uniform in green-leaved species.In conclusion,this study’s results provide clarity into the photoprotective mechanism of anthocyanins in red leaves,partially resolving the longstanding controversy regarding their photoprotection.The study suggests that anthocyanins primarily safeguard photosystem II by attenuating light,not by scavenging ROS or other methods.Upon further examination,it has been discovered that red-leaf species are more resistant to photoinhibition when exposed to solar radiation at 25°C than any of the five Prunus species studied.The temperature response curve of photosensitivity suggests that red-leaved species are less resistant to photoinhibition at high temperatures than green-leaved species.The physiological and ecological functions of yellow leaves during the growing season are not primarily photosynthetic,but rather involve protecting the photosynthetic function of internal leaves by filtering light.The distribution of chlorophyll content within the leaves of colored-leaf plants differs from that of green-leaf plants,potentially playing a unique role in resistance to photoinhibition and carbon assimilation.This study suggests ways to further investigate the physiological and ecological functions of anthocyanins in red leaves and flavonoids in yellow leaves during the growing season by providing research directions.At the same time,it provides theoretical guidance and reference for cultivating,allocating,and maintaining colored-leaf plants in urban landscapes.更多还原