Arróniz-Crespo María, Núñez-Olivera Encarnación, Martínez-Abaigar Javier, Becker Hans, Scher Jochen, Zapp Josef, Tomás Rafael, Beaucourt Nathalie
Universidad de La Rioja, Complejo Científico-Tecnológico, Avda. Madre de Dios 51, 26006 Logroño (La Rioja), Spain.
Pharmakognosie und Analytische Phytochemie, Universität des Saarlandes, Gebäude C2.2, D-66041 Saarbrücken, Germany.
Funct Plant Biol. 2006 Nov;33(11):1025-1036. doi: 10.1071/FP06096.
Here we report the effects of a natural altitudinal gradient of UV-B radiation, from 1140 to 1816 m altitude, on the physiology of the aquatic liverwort Jungermannia exsertifolia Steph. subsp. cordifolia (Dumort.) Váña collected in mountain streams. Photosynthetic pigments, net photosynthesis and dark respiration rates, chlorophyll fluorescence, protein concentration, sclerophylly, and UV-absorbing compounds [both global UV absorbance of methanol-extractable UV-absorbing compounds (MEUVAC) and concentrations of five individual compounds] were measured. Two new caffeic acid derivatives were discovered: 5″-(7″,8″-dihydroxycoumaroyl)-2-caffeoylmalic acid and 5″-(7″,8″-dihydroxy-7-O-β-glucosyl-coumaroyl)-2-caffeoylmalic acid, whereas three additional compounds were already known in other species: p-coumaroylmalic acid, phaselic acid (both compounds in their cis- and trans- forms) and feruloylmalic acid. Most physiological variables changed considerably along the altitudinal gradient, but only six showed significant linear relationships with altitude: MEUVAC levels, the concentrations of the two new secondary compounds, the maximal apparent electron transport rate through PSII (ETR) and the maximal non-photochemical quenching (NPQ) increased with altitude, whereas photoinhibition percentage decreased. A principal components analysis (PCA) was conducted to rank the values of the physiological and ecological variables obtained along the altitudinal transect, showing that those variables correlated with altitude were responsible for the ordination of the sampling points. The liverwort was not adversely affected by the changing conditions along the altitudinal gradient and, in particular, by the increasing UV-B irradiance, probably because the characteristics shown by high-altitude populations may confer tolerance to high UV-B levels. The response to UV-B of the two new compounds suggests that they could be used as indicators of the spatial changes in UV-B radiation.
在此，我们报告了海拔1140至1816米处紫外线B辐射的自然海拔梯度对水生叶苔类植物小角齿叶苔（Jungermannia exsertifolia Steph. subsp. cordifolia (Dumort.) Váña）生理学的影响，该植物采自山间溪流。我们测量了光合色素、净光合作用和暗呼吸速率、叶绿素荧光、蛋白质浓度、硬叶性以及紫外线吸收化合物[包括甲醇可提取紫外线吸收化合物（MEUVAC）的总体紫外线吸收率和五种单一化合物的浓度]。发现了两种新的咖啡酸衍生物：5″-(7″,8″-二羟基香豆酰基)-2-咖啡酰苹果酸和5″-(7″,8″-二羟基-7-O-β-葡萄糖基-香豆酰基)-2-咖啡酰苹果酸，而另外三种化合物在其他物种中已为人所知：对香豆酰苹果酸、phaselic酸（两种化合物均有顺式和反式形式）和阿魏酰苹果酸。大多数生理变量沿海拔梯度有显著变化，但只有六个与海拔呈现显著线性关系：MEUVAC水平、两种新次生化合物的浓度、通过PSII的最大表观电子传递速率（ETR）和最大非光化学猝灭（NPQ）随海拔升高而增加，而光抑制百分比则下降。进行了主成分分析（PCA）以对沿海拔样带获得的生理和生态变量值进行排序，结果表明与海拔相关的那些变量决定了采样点的排序。该叶苔类植物并未受到沿海拔梯度变化条件的不利影响，尤其是未受紫外线B辐照度增加的不利影响，这可能是因为高海拔种群所表现出的特征使其能够耐受高紫外线B水平。这两种新化合物对紫外线B的响应表明，它们可作为紫外线B辐射空间变化的指标。
