Tattini Massimiliano, Galardi Carlotta, Pinelli Patrizia, Massai Rossano, Remorini Damiano, Agati Giovanni
Istituto per la Valorizzazione del Legno e delle Specie Arboree, IVALSA, Consiglio Nazionale delle Ricerche, Via Madonna del Piano, I-50019, Sesto F.no, Firenze, Italy.
Dipartimento di Scienze Farmaceutiche, Università di Firenze, Via Ugo Schiff 6, I-50019, Sesto F.no, Firenze, Italy.
New Phytol. 2004 Sep;163(3):547-561. doi: 10.1111/j.1469-8137.2004.01126.x.
• The differential accumulation of various polyphenols, particularly of flavonoids and hydroxycinnamates, was studied in leaves of Ligustrum vulgare exposed to increasing sunlight under well watered or drought-stress conditions. • Light- and drought-induced changes in leaf polyphenol concentrations were normalized to the CO assimilation rate. The functional roles of flavonoids and hydroxycinnamates were analysed through tissue localization using multispectral fluorescence microimaging, and through efficiencies to scavenge superoxide radicals (O ) and to screen UV wavelengths. • Clear effects of light and water treatments on leaf polyphenol concentrations were not observed, as the CO assimilation rate varied according to sunlight and water availability. However, biosynthesis of quercetin 3-O-rutinoside, luteolin 7-O-glucoside and echinacoside, which were efficient O scavengers, increased sharply in response to solar radiation. By contrast, carbon for the synthesis of p-coumaric acid and monohydroxyflavones, efficient UV screeners but poor O scavengers, did not vary depending on light treatments. Flavonoids accumulated in both the adaxial epidermis and the palisade tissue because of sunlight irradiance, whereas echinacoside occurred largely in abaxial tissues. • We hypothesize that flavonoids may serve antioxidant functions in response to excess light and drought stress, and that a coordinate control system between hydroxycinnamate and flavonoid pathways operated in L. vulgare exposed to excess light.
• 研究了在水分充足或干旱胁迫条件下，随着光照增强，欧洲女贞叶片中各种多酚类物质，特别是黄酮类化合物和羟基肉桂酸酯的差异积累情况。
• 将光照和干旱诱导的叶片多酚浓度变化按照二氧化碳同化率进行归一化处理。通过多光谱荧光显微成像技术进行组织定位，并通过清除超氧阴离子自由基（O ）和筛选紫外线波长的效率，分析黄酮类化合物和羟基肉桂酸酯的功能作用。
• 未观察到光照和水分处理对叶片多酚浓度有明显影响，因为二氧化碳同化率随光照和水分供应情况而变化。然而，作为高效超氧阴离子自由基清除剂的槲皮素3-O-芸香糖苷、木犀草素7-O-葡萄糖苷和紫锥菊苷的生物合成，在太阳辐射下急剧增加。相比之下，用于合成对香豆酸和单羟基黄酮的碳，这两种物质是高效紫外线筛选剂但超氧阴离子自由基清除能力较差，其含量并不因光照处理而变化。由于阳光照射，黄酮类化合物在叶片的上表皮和栅栏组织中均有积累，而紫锥菊苷主要存在于下表皮组织中。
• 我们推测，黄酮类化合物可能在应对过量光照和干旱胁迫时发挥抗氧化功能，并且在暴露于过量光照的欧洲女贞中，羟基肉桂酸酯和黄酮类化合物途径之间存在协同控制系统。
