植物如何应对高山胁迫?

Encyclopédie environnement - stress plantes alpines - alpine plants

  在高海拔地区,植物可能会受到强烈的胁迫:光照和紫外线辐射强度高,二氧化碳浓度低,昼夜温差大……这些参数随季节变化,但在几天之内或者同一天内也会发生显著变化。生活在高山环境中的植物利用光提供的能量进行光合作用得以生长发育,而光照、二氧化碳等限制性因子会调节或干扰植物的光合作用。尤其是,过量的光能会导致有毒化合物的合成,如活性氧(ROS)。为了适应这些困境,高山植物进化出了各种策略:非常小的体形、抵御紫外线辐射的保护屏障、保护性的解剖结构、耗散多余光能的机制、对活性氧的毒性消解等。

1.高山植被

环境百科全是-生命-不同高山层的植被
图1. 不同高山层的植被。这些照片展示了北阿尔卑斯山(the Northern Alps))的高山和亚高山地区的植被,区域边界(或称群落交错区)随着光照度的不同而变化,光照最强的面通常是山的南面,光照最少的面是北面。A1,高山景观;A2,在加利比尔附近拍摄的宿萼毛莨(Ranunculus glacialis)。B,贝尔多恩地块的亚高山地面景观。C,不同植被层的理论示意图。[资料来源:A1,©阿兰·赫罗(Alain Herrault);A2,©谢尔盖·奥伯特(Serge Aubert),阿尔卑斯山约瑟夫傅里叶站(Station alpine Joseph Fourier);B,©雅克·乔亚德(Jacques Joyard);C,皮瑟斯(CCBY-SA3.0)通过维基共享的图表(diagram by Pethrus via Wikimedia Commons)](图1 Shady side 阴面;Sunny side阳面;Nival stage积雪层;Alpine stage高山层;Subalpine stage亚高山层;Mountain stage山地层;Hill stage山坡层)

  在山区,从山谷到山顶,植被具有独特的地带性。在高山地区,低处是落叶林,到1800—2300米时,落叶林逐渐被针叶林所取代,具体取决于针叶林在何处出现取决于该地光照度(即阳面还是阴面):覆盖有一片疏林、其上为孤立树木的是亚高山层。再高一些,大约3000米处,是被草坪覆盖的斜坡,此处为高山层。高山层之上,破碎化植被以被岩石、碎石等分隔的植被区域为特征。、苔藓、地衣、裸岩和终年积雪替代了高山草坪,此处为积雪层[1][2](图1)。在高海拔地段,植物多样性急剧下降[3],这时,气候因素似乎是大多数植物生长的限制性因素。

2.气候条件和生长季

环境百科全是-生命-积雪下的植物
图2 积雪下的植物。左图为春天高山雪铃花(Soldanella)穿破雪层。右图为7月份一场降雪后所拍摄的毛茛宿萼(Ranunculus glacialis)。[资料来源:照片©彼得·斯特雷布(PeterStreb)]
  每上升100米平均气温降低约0.65摄氏度(参见“地球大气层和气体包络层”)[1]。随着海拔升高,降水量以降雪的形式增加,雪覆盖时间较长,从而限制了植被生长阶段植物生长、发育和繁殖的时期。 这一时期与种子、孢子、地下器官或落叶树形式的较慢生命阶段形成鲜明对比[2]。在高海拔地区,植物通常是“多年生的”,即可以存活几年[3]。一年生植物每年发芽、生根、抽枝、长叶和开花,并在较短的生长季节产生新的种子(参见“高山植物的繁殖策略”)。然而,多年生植物可通过冬眠,在其根、鳞茎、块茎和根状茎(携带叶芽和根芽的地下茎。根茎可以是水平的,或多或少靠近地表,如鸢尾,也可以更深,如田旋花。)中储备能量。一些植物种还会保持其根和叶的存活状态,待春季地面雪融化后立即快速复苏。

  因此,多年生植物的优势是在生长季节只形成少数器官,而一年生植物必须形成它们所有的器官,这会使得植物在有限的时间内消耗大量的能量。

环境百科全是-生命-无茎蝇子草(Silene acaulis)
图3 无茎蝇子草(Silene acaulis)。一种高山草垫植被,能够抵御极低温度。[资料来源:照片©彼得·斯特雷布(PeterStreb)]
  此外,多年生植物的存活器官必须要忍受冬季低温,我们测量到高山植物的冰点在一年内有所差异,其在冬天时降到最低值[3],[4]。例如,在此期间,高山雪铃花(Soldanella alpina)的绿叶能够抵抗零下20摄氏度的低温,而苔草(Carex firma)和无茎蝇子草(Silene acaulis)能够忍受更极端的低温,分别为零下70摄氏度和零下196摄氏度[4]。也许,这些低冰点能够帮助在积雪之外的高山植物度过特殊的艰难时期。而事实上,积雪下温度总是高于积雪外面的温度[4],因此,植物是否具有承受极端低温的能力,大概率不会影响其在高海拔地区的分布。

3.光合作用

  在生长季,植物通过光合作用来保障自身的生长发育,在这个过程中,太阳辐射提供必需的能量,才使得植物能够利用大气中吸收到的二氧化碳、水和土壤中的矿物质,合成有机物质。由于光合作用被这些高海拔地区存在的多种限制因子所影响[5],也许,能否在胁迫条件下保持光合作用,决定了植物能否在高海拔地区存活。光合作用的主要反应过程如图4所示,详细情况见[6]。图4还描述了高山植物为维持这一光合过程而具有的特性。

环境百科全是-生命-一个含叶绿素的细胞的示意图
图4 一个含叶绿素的细胞的示意图。图片显示了叶绿体、细胞质(含有线粒体和过氧化物酶)以及参与光合作用的主要蛋白质复合物之间的关系。黄色部分表示的是,与类囊体膜相关的光合作用初级反应中的光吸收和电子传递作用。详细信息请参见文本。该反应包括蛋白复合物PSII、Cytb6f、PSI和atp酶。黑色箭头表示二次反应中二氧化碳同化和糖合成所利用的能量以及它们在细胞中如何被利用的过程。还有其他方法利用所吸收的能量(如红色所示),这个过程可以保护光合作用,以热量的形式散发过多的能量,通过PTOX蛋白质减少水中氧气的形成,PSI中形成ROS以及抗氧化剂对ROS进行解毒,最后是Rubisco吸收氧气引发光吸收途径。有关详细信息,请参见文本。[图 ©彼得·斯特雷布(Peter Streb);缩写;AT(D)P:腺苷三(二)磷酸;Cytb6/f:细胞色素b6/f;e:电子-PSII和NADP+之间的电子传递;Fe:铁;FNR:铁氧嘧啶-NADP-还原酶;NADP(+H:烟酰胺腺苷二核苷酸(+氧化型,H还原型);PSI&PSII:光系统I和光系统II;PTOX:替代氧化酶;Rubisco:核糖双磷酸羧化酶加氧酶(催化二氧化碳固定的酶复合物);SDP:蔗糖-二磷酸(Rubisco的底物);TP:磷酸丙糖(二氧化碳同化后首次出现的磷酸化糖)。](图4 STARCH淀粉;TP磷酸丙糖;SUCROSE蔗糖;export输出;CO2二氧化碳;O2氧气;Secondary reactions第二反应阶段;Antioxydant抗氧化;Chloroplast叶绿素;Primary reactions原初反应阶段;Chaleur热能;PSII光系统II;PSI光系统I;PTOX质体末端氧化酶;ATPase ATP酶;NADPH 烟酰胺腺嘌呤二核苷酸磷酸;Fe铁;NADPh还原型辅酶II;NAD+烟酰胺腺嘌呤二核苷酸;NADH还原性辅酶I;Peroxysome过氧化物酶体;Mitochondria线粒体;respiration呼吸作用;Metabolism新陈代谢;Cytoplasm细胞质;ADP二磷酸腺苷;P磷;ATP三磷酸腺苷;photorespiration光呼吸;Benson Calvin Cycle卡尔文循环)
  光合作用发生在叶绿体中,叶绿体是进行光合作用的真核细胞(植物、藻类)胞质中的细胞器。作为光合作用的场所,叶绿体产生氧气,并在碳循环中发挥重要作用。它们利用光能固定二氧化碳并合成有机物。因此,它们负责植物的自养。叶绿体是约15亿年前真核细胞内一种光合原核生物(蓝藻型)内共生的结果。光合作用可分为两个阶段。

  • 原初反应阶段发生在类囊体薄膜上:光能被光合色素(聚光叶绿素)吸收,随后转移到两个反应中心(光系统I和光系统II:PSI 和PSII),其协同活性通过一系列氧化还原反应,在PSI中将NADP+还原为NADPH(是辅酶烟酰胺腺嘌呤二核苷酸磷酸(NADP)的还原型。NADP 由烟酰胺腺嘌呤二核苷酸(或 NAD)通过与腺嘌呤相关核糖的 2羟基结合形成。它以氧化态(NADP+)和还原态(NADPH)存在。据说,NADPH 具有还原能力:在氧化还原酶进行的催化反应中,它能够在氢原子转移过程中提供能量,从而进行细胞功能所需的还原反应。),还原所需要的电子来自于PSII中水的氧化反应(2H2O → O2+ 4H+ + 4e)。原初反应阶段也诱导在类囊体膜上建立质子梯度,为ATP(三磷酸腺苷的缩写。一种三磷酸核苷,由腺嘌呤(氮基)、核糖(含5个碳原子的糖)和三个磷酸基团组成一个三磷酸基团。所有生物体中都存在的一种既能提供能量又能储存能量的化合物。也可用作核酸合成的原料。)的合成提供必要的能量(图4)。
  • 光合作用的第二阶段发生在叶绿体基质中。它通过消耗ATP和NADPH来固定大气中的二氧化碳到由5个碳原子(二磷酸核酮糖,RuBP)作为骨架形成的二磷酸糖中(RuBisCO活性(1,5-二磷酸核酮糖羧化酶/加氧酶的缩写。 它是利用光合作用过程中叶绿素捕获的太阳能启动本森和卡尔文循环来固定植物生物质中二氧化碳的关键酶。)),从而产生含有三个碳原子的磷酸糖(磷酸三糖,简称TP)(图4)。这种迅速形成三碳化合物的光合作用过程,是C3植物(实行C3途径的植物)的特征。高山植物绝大多数为此类植物。

  吸收了二氧化碳而形成的磷酸三糖(TP),在叶绿素细胞内有多种用途:(1)重新形成二氧化碳受体;(2)用于叶绿体中葡萄糖淀粉的合成;(3)被输送到细胞的其他细胞器中,为它们的运作提供能量和碳链;(4)用于合成蔗糖,并输送到植物的其他部分,提供能量和碳骨架,以合成大量化合物[6]。还需要注意的是,氧气可以与二磷酸核酮糖结合:这种氧化过程是代谢途径和光呼吸的起始,光呼吸也同样消耗ATP和NADPH(图4)。

4.环境因素在光合作用中的重要性

4.1.温度

  在光合作用过程中,温度主要影响二氧化碳和氧气固定,以及糖合成的反应,但也影响细胞间分子的交换。光合作用的两个主要阶段以及所涉及到的运输过程受温度的影响不同:

  • 叶绿素色素吸收光、NADPH和ATP形成等生物物理过程,并不依赖或者是仅轻微依赖于温度。
  • 二氧化碳和氧气吸收、糖合成这类生化反应,以及细胞间的分子交换,都高度依赖温度[7]。一般而言,增温10摄氏度会使得生化反应速率加倍。

环境百科全是-生命-测量高山植物温度与光照强度
图5 测量高山植物温度与光照强度。左图:在劳塔雷特·帕斯的2400米高处,所测得的高山雪铃花(Soldanella)叶表面的温度和光照强度(以光子通量密度表示),图上显示了最大值和最小值。昼夜热变化最大的幅度为32°C,同一小时内热变化最大为15°C。在一小时内,光子通量密度可在2000µmol m-2s-1之间变化。右图:安装在高山雪铃花(Soldanella)上的温度和光传感器。[来源:图表©彼得·斯特雷布(Peter Streb)和康斯坦斯·劳罗(Constance Laureau),未发表;图片©康斯坦斯·劳罗(Constance Laureau)](图5 Temperature温度;Photon flux densite光通量;Maximum最高点;Minimum最低点;heure du jour一天中的时间)
  在生长季,高山植物叶片生活的温度在昼夜之间可以变化30°C ,白天的同一时间温度可以变化15°C (图5)。因此,生化反应的速率在晚上和白天之间可能相差8倍,在叶片的同一小时内可以变化3倍。综上所述:在一定的温度下,叶片所捕获的光能并不完全被生化反应所消耗。

  例如,冰山金凤花(glacier buttercup),在23°C时、2000µmol photons m-2 s-1的光照下可以固定大概15µmolCO2 m-2 s-1(光通量数量级见图5),而其在10°C时只固定一半的二氧化碳。第一种情况下,光照不足,二氧化碳的固定足以抵消光照带来的能量,然而,在第二种情况下,二氧化碳的固定在500µmolphotons m-2 s-1下已经饱和,因此光基本上是过量的[8]

4.2.光照

  和温度一样,在高山环境下,光照可以在同一天突然变化几个数量级(图5)。在多云的天气下,山谷和高海拔地区[3]的平均光强差异不是很大。另一方面,在晴朗天气下,高海拔地区的最大光强度要大得多,超过了大多数植物的光合能力。就像温度骤降一样,极强光照会导致叶子中的能量过剩,从而损害光系统[7]

  此外,较高海拔地区的紫外线辐射(UVA和UVB)更强[9],这直接影响细胞结构:光系统,以及叶绿体、线粒体和细胞核中的DNA(参见“太阳紫外线对细胞的影响”)。在PSII中,参与产氧的锰(图4)和在PSII和细胞色素b6f(cytb6f)之间运输电子的质体醌,会直接吸收紫外线辐射,当紫外线辐射过高时,这些功能可能会受到抑制[10]

  阴生植物利用高山带常有的中强光,但如果光照强度过高,就会受到胁迫。另一方面,阳生植物对高强光更耐受,但对弱光的利用率很低[11]。此外,艳丽的高山植物,如高山雪铃花(Soldanella alpina)、山雏菊(Homogyne alpina )或毛茛宿萼(Ranunculus glacialis)等(图2),对弱光或强光没有表现出任何典型的特异性适应[12]

4.3.其他影响因子

  影响光合活性的其他高山环境因子:

  • 例如,高海拔地区,二氧化碳的量随气压的降低而减少[7]
  • 会增加植物干枯的风险,而风的强度取决于地形。
  • 斜坡会使得水分流动,降低土壤持水性[3]

  然而,为应对水分胁迫,植物会关闭其气孔(控制叶片气体交换的特殊细胞):这限制了二氧化碳的供应,并减缓了光合作用。同样,光合作用的生化反应也不能消耗植物接收到的多余光能。

  综上所述,山区的气候因子(如光照、温度、湿度)变化强烈、迅速,变化幅度较大。大多数平原植物在这种变化中是无法存活的,因为光合作用无法利用过剩的能量[7]。这些过剩的能量可以通过形成活性氧(ROS)转移到氧气中(图4,[12])。活性氧(ROS)是具有极强潜在破坏性的分子,它们不仅会损害光合作用装置,特别是光系统II(光抑制系统),还会损害到整个细胞(参见“植物的生长年限及其限制因子”)。最终,植物的光合能力可能会受到活性氧(ROS)的抑制,其修复损伤的能力也会大大降低[11]

4.4. 高山植物光合作用的限制条件是什么?

  高山环境所施加的胁迫可以用以下两种极端情况进行说明。一些高山植物,如高山雪铃花、水杨梅和高山良姜等,在冬季保留会一些绿叶。在高光强度和高热梯度相结合的条件下,这些叶片在雪融后立即开始进行光合作用[7]。这些高山植物会在融雪后的短时间内进行光合作用,因为几周后它们就会被其他植物遮蔽。在极端气候下,光合作用失活对这些植物可能是致命的。然而,大多数高山植物在冬天不保留叶子,必须快速利用所储存的能量去形成它的第一片叶子,确保它们在短周期内的发育。以毛茛宿萼(Ranunculus glacialis)(见图2)为例,我们仅在2200米以上发现毛茛宿萼(Ranunculus glacialis),这表明它的生存过程可能更加复杂。事实上,在这种植物中,据计算,形成叶片所调动的储备大约相当于30天的光合作用,这在生长季节很难实现(见图2)。由于毛茛宿萼(Ranunculus glacialis)需要两年的时间才能成熟[12],这表明在一个生长季节获得的能量不足以支撑其在一年内完成发育周期。因此,毛茛宿萼(Ranunculus glacialis)不存在光合作用失活的风险。一些高山物种的矮化现象也可以被认为是限制光合作用组织形成能量投资的一种策略。

5.高山植物的适应性

  植物的适应性使其对环境的影响作出反应,在细胞和分子被影响到之前,减少环境引起的生理指标变化的幅度。当这些反应不足以缓解这些消极影响时,植物的适应性就通过其他保护措施表现出来,以防止细胞或其细胞器被破坏。

  高山植物通常表现为垫状(参见图3)、莲座状或簇状特殊结构(参见“遗传或趋同作用”),这种形态使得植物生活在一个有利的小气候[3]中,如:(1)叶片组织所吸收的光强和紫外辐射减少;(2)叶片湿度增加,防风,避免干燥;(3)比起周边空气,植物温度变化更小。这种形态的形成代表了其具有抗逆性。当然,这些植物比不形成这些结构植物的生长速度更慢,这是高山植物为此需要付出的代价。

  如上所述,极大热变化与高光照度能诱导光系统II的光抑制和活性氧(ROS)的形成。

环境百科全是-生命-高山植物在胁迫和光照条件下叶片的能量流动及保护机制
图6 高山植物在胁迫和光照条件下叶片的能量流动及保护机制。(1)一些辐射被表皮的黄酮吸收,特别是紫外线辐射。(2)光系统吸收的一些能量可以热量的形式散发。(3)一些多余的电子可能通过PTOX或活性氧(ROS)转移到氧气中形成水,或被光呼吸消耗。活性氧(ROS)可以通过抗氧化系统解毒。(4)高山植物部分糖和代谢物的合成。详情请参见图4。[资料来源:图表由彼得·斯特雷布(Peter Streb)提供]
(图6 STRESS CONDITIONS胁迫条件;Ex: high light+UV, and extreme temperature例:强光+紫外线,极端温度;1.Absorption of UV by flavonoids通过类黄酮吸收紫外线;Absorption light by photosystems通过光合系统吸收光;Energy emission as heat以热能的形式释放能量;2.ectron transport电子传递;Detoxication of ROS活性氧的解毒;3.Alternative pathways for consumption of excess electrons: PTOX, ROS formation, photorespiration 多种消耗过剩电子的途径:质体末端氧化酶,活性氧,光呼吸;CO2 assimilation吸收二氧化碳;4.Synthesis of alternative metabolites: Ascorbate, ranunculin, malate, methylglucose 合成多种代谢产物:抗坏血酸,毛茛甙,苹果酸,甲基葡萄糖)
与低地植物相比,我们研究的高山植物[7]对光抑制具有更强的抗性。为此,高山植物采用了不同的保护机制,这些机制大多数也存在于低地植物中。这些是发生在多个组织层级的回避机制(多种保护机制的详细信息见图4)。它们可以分为两类:“上游”机制,避免能量到达反应中心的速度过快;“下游”机制,即使在不利条件下,也要保持光合反应中所分离出电子的利用(即充分使用聚光色素所捕获的光能)(见图6)。
  • 防止紫外线辐射。在植物的表皮层,一些物种能够合成植物的此生代谢产物——黄酮类物质,这类物质都有相同的基本结构。黄酮类化合物是多酚类化合物中最重要的一类,是一个庞大的抗氧化剂家族。黄酮类化合物是植物花、果产生棕色、红色和蓝色色素的原因,这些色素可以吸收高能的紫外辐射因此,紫外线不会刺激到下层细胞。因此,这种类黄酮屏障可以保护光系统,防止含叶绿素的薄壁细胞的DNA遭到破坏。叶绿体作为光合作用的场所,它们参与植物的营养功能。它们也是叶片内部的重要组成部分。以高山雪玲花为例,高强度光照会诱导其类黄酮含量上升,从而保护植物,且这种保护的力度随着海拔的升高而增加[13]
  • 所吸收的过剩能量的再发射。光照植物聚光色素构象变化;与此同时,一些被激活的叶绿素将其能量传递给类胡萝卜素(例如玉米黄素)。这使得一些光能以热量的形式耗散(图4)。这样,到达反应中心的能量就被控制了。在过量的光照下,热耗散的光能量高于直接传到反应中心的光能量,热耗散是一种去除叶绿素激发态的快速方法。在一些像高山雪铃花和水杨梅花这类高山植物中,这种回避机制非常有效,而在其他像毛莨宿萼(Ranunculus glacialis)这类物种中,这种机制就不是那么有效了,而是激活其他机制(见下文)[7]
  • 能量通过电子流转移到替代受体。在叶绿体中,连接两个光系统的替代氧化酶(称为PTOX)(叶绿体类囊体膜的酶,催化质体醌库的氧化,因此得名替代氧化酶(PTOX)。)(图4),接受PSII提供的电子,并将其转移到氧分子中,从而形成水。因此,这种酶可以降低电子压力,减少因过量光照而形成的活性氧(ROS)。与低地植物相比,高山植物内替代氧化酶含量高,且其浓度随着海拔的升高而增加。
  • 在低温下维持光合代谢。如果二氧化碳的供应限制了光合作用第二阶段糖的合成,Rubisco酶会催化分子氧与二磷酸核酮糖的结合。这是光呼吸系统的第一步(图4)。光呼吸作用消耗能量,其形式包括(a)碳(二磷酸核酮糖)、(b)光合作用第一阶段产生的电子和(c)ATP。在低温下,光呼吸作用通常可以忽略不计,但当温度超过20摄氏度时,光呼吸作用就会很重要。对于不耐热的毛茛宿萼(Ranunculus glacialis)来说,温度很低时,其光呼吸作用就已经很活跃了。
  • 特定代谢产物的合成。一些高山植物合成的代谢物在低地植物中通常不存在或少量存在。这些代谢物的功能往往尚不清楚。但这些代谢物的合成会消耗光合作用装置所捕获的部分能量,从而可以帮助保护光合作用装置。因此,毛莨会积累大量的毛莨苷和苹果酸[14]苹果酸盐是一种广泛应用于植物界的二羧酸,天然存在于水果中,使水果味道宜人。苹果酸是克雷布斯循环的中间体,克雷布斯循环是几乎所有生物细胞呼吸的主要代谢途径之一,苹果酸还参与光合作用中的本森和卡尔文循环。用作食品添加剂,编号为 E296[14]。水杨梅含有高浓度的甲基葡萄糖,而高山雪铃花的叶片[15]中含有创纪录数量的抗坏血酸(维生素C)。抗坏血酸是抗氧化系统的一部分,可以保护植物免受活性氧(ROS)的侵害。
  • 高活性氧(ROS)的解毒。环境胁迫增加了活性氧(ROS)的形成,特别是在光合作用的原初反应阶段。如图4所示,活性氧(ROS)的形成显示在PSI水平上:它是在光照下活性氧(ROS)形成的主要途径。为了将活性氧(ROS)降解为氧气,植物会进行一系列与代谢产物相关的酶反应。在高山雪铃花的叶片中,维生素C、维生素E和参与氧化还原过程的酶是抗氧化系统所必需的。在委陵莱中,叶片抗氧化系统的重要性随着海拔的升高而增加[16]

  简而言之,正是这样一套保护机制,不仅可以让高山植物存活下来,而且可以使其在随着海拔升高、限制作用日益增强的栖息地生活。这些保护机制相互补充,帮助植物在高山环境中生存下来(图6)。

 


参考资料和说明

封面照片: 加利西亚岩层上的高山柳穿鱼(Linaria alpina)(2600m处)。 [来自: 照片©谢尔盖·奥伯特(Serge Aubert)/阿尔卑斯山约瑟夫傅里叶站(SAJF)]

[1] Ozenda P., La végétation de la chaîne alpine dans l’espace montagnard européen, Masson, 1985

[2] Fischesser B., La vie de la montagne, Éditions de La Martinière, Paris, 1998

[3] Körner C., Alpine plant life, Springer Verlag, Berlin Heidelberg, 1999

[4] Larcher W., Kainmüller C., Wagner J., Survival types of high mountain plants under extreme temperatures, Flora, 205:3-18, 2010

[5] Lütz C., Plants in Alpine Regions, Cell Physiology of Adaptation and Survival Strategies, Springer, Wien New York, 75-97, 2012

[6] Raven P., Evert R., Eichhorn S., Biology of Plants, Sixth Edition, W.H. Freemann and Company/Worth Publishers, 1986

[7] Streb P., Cornic G., Photosynthesis and Antioxidative Protection in Alpine Herbs, In Lütz C. (Ed) Plants in Alpine Regions: Cell Physiology of Adaptation and Survival Strategies, Springer Wien New York, pp 75-97, 2012

[8] Streb P., Josse E.-M., Gallouët E., Baptist F., Kuntz M., Cornic G. (2005) Evidence for alternative electron sinks to photosynthetic carbon assimilation in the high mountain plant species Ranunculus glacialis. Plant, Cell Environment 28:1123-1135

[9] Barry R., Mountain weather and climate, Cambridge University Press, Third Edition, 2008

[10] Teramura A., Ziska L., Ultraviolet-B radiation and photosynthesis, In “Advances in Photosynthesis Vol. 5: Photosynthesis and the Environment“. Ed. N.R. Baker, pp 435-450, Kluwer Academic Publishers, Dordrecht, 1996

[11] Walters R., Towards an understanding of photosynthetic acclimation, Journal of Experimental Botany 56:435-447, 2005

[12] Ort D., Baker N., A photoprotective role of O2 as an alternative electron sink in photosynthesis? Current Opinion in Plant Biology 5:193-198, 2002

[13] Laureau C., Meyer S., Baudin X., Huignard C., Streb P. (2015) In vivo epidermal UV-A absorbance is induced by sunlight and protects Soldanella alpina leaves from photoinhibition. Functional Plant Biology, 42:599-608

[14] Streb P., Aubert S., Gout E., Bligny R. (2003) Reversibility of cold- and light-stress tolerance and accompanying changes of metabolite and antioxidant levels in the two high mountain plant species Soldanella alpina and Ranunculus glacialis. J. Exp. Bot. 54:405-418

[15] Bligny R., Aubert S., Specifities of metabolite profiles in alpine plants. In Lütz C. (Ed) Plants in Alpine Regions: Cell Physiology of Adaptation and Survival Strategies, Springer, Wien & New York, pp 99-120, 2012

[16] Lan Ma, Xudong Sun, Xiangxiang Kong, Jose Valero Galvan, Xiong Li, Shihai Yang, Yunqiang Yang, Yongping Yang, Xiangyang Hu, Physiological, biochemical and proteomics analysis reveals the adaptation strategies of the alpine plant Potentilla saundersiana at altitude gradient of the Northwestern Tibetan Plateau, Journal of Proteomics, 112:63-82, 2015


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引用这篇文章: STREB Peter, CORNIC Gabriel, BLIGNY† Richard (2024年3月12日), 植物如何应对高山胁迫?, 环境百科全书,咨询于 2024年10月8日 [在线ISSN 2555-0950]网址: https://www.encyclopedie-environnement.org/zh/vivant-zh/how-do-plants-cope-with-alpine-stress/.

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How do plants cope with alpine stress?

Encyclopédie environnement - stress plantes alpines - alpine plants

At high altitudes, plants can be subjected to strong constraints: high light and UV radiation, low CO2 concentration, large temperature variations… These parameters vary over the seasons but can also change significantly from one day to another as well as during the same day. These constraints modulate and sometimes disturb photosynthesis, which uses the energy provided by light and allows the growth and development of plants living in the alpine environment. In particular, excess light energy leads to the formation of toxic compounds, such as reactive oxygen species (ROS). To adapt to these difficult conditions, alpine plants developed various strategies: very small size, protective screen against UV radiation, protective anatomical structures, mechanisms to dissipate excess light energy, detoxification of reactive oxygen species, etc.

1. Vegetation in the alpine stages

Figure 1. The various levels of vegetation in the mountains. The photographs represent the vegetation in the alpine and subalpine zones of the Northern Alps. The boundaries of the zones (or ecotone) vary with exposure: the sunniest face is generally the south face of a mountain, the least sunny face is the shady face, facing north. A1, alpine landscape; A2, Ranunculus glacialis, photo taken near the Galibier. B, landscape of the subalpine floor in the Belledonne massif. C, Theoretical representation of the various vegetation levels [Sources: A1, © Alain Herrault ; A2, © Serge Aubert, Station alpine Joseph Fourier; B, © Jacques Joyard; C, diagram by Pethrus (CC BY-SA 3.0) via Wikimedia Commons]
In mountains, the vegetation has characteristic zonations from valleys to peaks. In the Alps, deciduous forests are found in the lower parts, gradually replaced by conifers up to 1800-2300 m, depending on the exposure (sunny or shady side): it is the subalpine stage with an open forest and isolated trees in the upper part. Higher up, up to about 3000 m, the slopes are covered with lawns: this is the alpine stage. Beyond that, the alpine lawn gives way to a disjoint vegetation coverCharacterizes an area of vegetation divided by rocks, screes, etc., mosses and lichens, bare rocks and eternal snow: this is the nival stage [1],[2] (Figure 1). Plant biodiversity then declines sharply at high altitudes [3], with climatic factors seeming to be a barrier to the development of most plants.

2. Climatic conditions and the growing season

Encyclopédie environnement - stress plantes alpines - Des plantes sous la neige - plants under snow
Figure 2. Plants under the snow. On the left, Soldanella alpina piercing the snow in spring. On the right, Ranunculus glacialis photographed after a snowfall in July. [Source: Photos © Peter Streb]
The average air temperature decreases by about 0.65°C every 100 m [1] (see The Earth’s atmosphere and gaseous envelope). With increasing altitude, the precipitation is in the form of snow increases, which remained for a longer period, thus limiting the vegetation periodThe period when a plant grows, develops and reproduces. This period is in contrast to the slower life phases in the form of seed, spore, underground organ, or defoliated tree [2]. At high altitudes, plants are most often “perennial”: they survive for several years [3]. Annual plants germinate, form roots, stems, leaves and flowers, every year and produces new seeds during a short growing season (see Reproductive strategies of alpine plants). On the other hand, perennial plants enter dormancy in winter and keep reserves in the roots, bulbs, tubers and rhizomesUnderground stem that carries leaf and root buds. A rhizome can be horizontal and more or less close to the surface, such as the iris, or much deeper, such as the bindweed.. In some species, the stems and leaves remain alive, which allows them to restart quickly in spring, as soon as the ground is free of snow.

Thus, perennial plants have the advantage of neo-forming only a few organs during the growing season whereas annual plants must form all their organs, which consumes a lot of energy for a limited time.

Encyclopédie environnement - stress plantes alpines - Silene acaulis - plants moutains
Figure 3. Silene acaulis, an example of an alpine cushion plant that resists very low temperatures. [Source: Photo © Peter Streb]
On the other hand, the survival organs of perennial plants must tolerate low winter temperatures. Freezing temperature has often been measured in alpine plants. They change during the year, falling to its lowest level during winter [3],[4]. For example, during this period, the green leaves of Soldanella alpina (Figure 2) resist -20°C, while those of Carex firma and Silene acaulis (Figure 3) withstand more extreme temperatures: -70°C and -196°C respectively [4]. It is likely that these low freezing temperatures can help alpine plants in the event of particularly severe episodes, outside the snow cover. Indeed, the temperature under the snow is always higher than in the open air [4]. Thus, it is likely that the ability to withstand very low temperatures is not likely to limit the distribution of plants at high altitudes.

3. Photosynthesis

During the growing season, plants ensure their growth and development through photosynthesis. In this process, the necessary energy is provided by solar radiation, which allows the synthesis of organic matter from carbon dioxide taken from the atmosphere, and water and minerals taken from the soil. Because photosynthesis is affected by multiple environmental constraints such as those present at high altitude [5], it is likely that the maintenance of photosynthesis under stress conditions determines the survival of plants at high altitude. The main reactions of photosynthesis are summarized in Figure 4 and detailed in [6]. Figure 4 also describes the particularities implemented by alpine plants to protect this process.

Figure 4. Schematic representation of a chlorophyll-containing cell showing some aspects of the cooperation between chloroplast, cytoplasm (with mitochondria and peroxysomes), and the main protein complexes involved in photosynthesis. Light absorption and electron transport in the primary reaction of photosynthesis, related to the thylakoid membrane, are shown in yellow. This reaction includes the protein complexes PSII, Cytb6f, PSI and ATPase. The black arrows show the use of energy for CO2 assimilation in the secondary reaction and for sugar synthesis as well as their use in the cell. There are also alternative ways of using absorbed energy (shown in red), whose functioning can protect photosynthesis: the emission of excess energy in the form of heat, the reduction of oxygen in water by the PTOX protein, the formation of ROS by the PSI and their detoxification by antioxidants, finally the photorespiration path initiated by the absorption of oxygen by Rubisco. For details see the text. Diagram © Peter Streb. Abbreviations ; AT(D)P: Adenosine tri(di)phosphate; Cytb6/f: cytochrome b6/f; e: electron – electron transport between PSII and NADP+ is indicated; Fe: Ferredoxine; FNR: Ferredoxine-NADP-Reductase; NADP(+H : Nicotinamide adenosine di-nucléotide phosphate (+ oxidized form, H reduced form); PSI & PSII: photosystem I and II; PTOX: plastic terminal oxidase; Rubisco: ribulose-bis-phosphate carboxylase oxygenase (enzyme complex that catalyzes CO2 fixation); SDP: sucrose-di-phosphate (substrate for Rubisco); TP: triose phosphate (first phosphorylated sugar appearing after CO2 assimilation).

Photosynthesis takes place in the chloroplastsOrganites of the cytoplasm of photosynthetic eukaryotic cells (plants, algae). As a site of photosynthesis, chloroplasts produce O2 oxygen and play an essential role in the carbon cycle. They use light energy to fix CO2 and synthesize organic matter. They are thus responsible for the autotrophy of plants. Chloroplasts are the result of the endosymbiosis of a photosynthetic prokaryote (cyanobacterium type) within a eukaryotic cell, about 1.5 billion years ago. and can be divided into two phases.

  • A primary phase takes place in the membrane of the thylakoids: the solar energy is absorbed by photosynthetic pigments (chlorophylls forming collecting antennas), then transferred to two reaction centres (photosystem I and II: PSI and PSII) whose coordinated activity results, via a succession of redox reactions, in the reduction of NADP+ to NADPHSigle for the reduced form of the coenzyme Nicotinamide Adenine Dinucleotide Phosphate (NADP). NADP is formed from Nicotinamide Adenine Dinucleotide (or NAD) by binding a phosphate to the 2′ hydroxyl group of the ribose associated with adenine. It exists in an oxidized form, called NADP+, and a reduced form, called NADPH. The NADPH is said to carry reductive power: used in catalyses carried out by oxidoreductases, it is capable of supplying energy during the transfer of their hydrogen atom, allowing the reduction reactions necessary for cellular functioning. by the PSI. The electrons involved come from the oxidation of water (2H2O → O2 + 4H+ + 4e) at the PSII level. This primary phase also induces the establishment of a proton gradient on the thylakoid membrane which provides the energy necessary for the synthesis of ATPAbbreviation of adenosine triphosphate. A triphosphate nucleoside composed of adenine (nitrogen base), ribose (sugar with 5 carbon atoms) and three phosphate groups forming a triphosphate group. A compound that both donates and stores energy present in all living organisms. Also used as building materials for nucleic acid synthesis. (Figure 4).
  • The second phase of photosynthesis takes place in the chloroplast stroma. It consumes the ATP and NADPH formed to fix atmospheric CO2 on a sugar di-phosphate (activity of RuBisCOAbbreviation for ribulose-1,5-bisphosphate carboxylase/oxygenase. It is the key enzyme for fixing CO2 carbon dioxide in plant biomass by initiating the Benson & Calvin cycle, using solar energy captured by chlorophyll during the photosynthesis process.), whose skeleton is formed by 5 carbon atoms (Ribulose bisphosphate or RuBP) and give sugar-phosphates with three carbon atoms (Triose-phosphate, in short TP) (Figure 4). This type of photosynthesis, which quickly leads to the formation of compounds with 3 carbons, is characteristic of C3 plants (C3 for 3 three carbons). The latter constitute the vast majority of alpine plants.

Trioses phosphate (TP), which contain assimilated CO2, can be used in chlorophyll-containg cells in several ways: (1) to regenerate the CO2 acceptor; (2) for the synthesis of glucose and starch in the chloroplast; (3) to be exported to other compartments of the cell where they provide energy and carbon chains for its maintenance; (4) for the synthesis of sucrose which is exported to other parts of the plant as an energy source and supplier of carbon skeletons feeding numerous biosyntheses [6]. Note also that oxygen can bind to RuBP: this oxygenation is at the origin of a metabolic pathway, photorespiration, which also consumes ATP and NADPH (Figure 4).

4. Importance of environmental factors in photosynthesis

4.1. Temperature

During photosynthesis, temperature mainly affects reactions allowing the binding of CO2 and O2 and the synthesis of sugars, but also the exchange of molecules between cellular compartments. The two main phases of photosynthesis and the transport processes involved are affected differently by temperature:

  • Biophysical processes such as light absorption by chlorophyll pigments and the formation of NADPH and ATP are not or only slightly temperature dependent.
  • The biochemical reactions of CO2 and O2 assimilation and sugar synthesis, as well as the exchange of molecules between cell compartments, are highly temperature dependent [7]. On average, a 10°C increase doubles the rate of biochemical reactions [6].

Encyclopédie environnement - stress plantes alpines - Mesure de la température et de l’intensité lumineuse au niveau des plantes alpines - temperature and light intensity in alpine plants
Figure 5. Measurement of temperature and light intensity in alpine plants. Graphs on the left: Temperature & light intensity (expressed as photon flux density) measured at 2400 m in the Lautaret Pass area on the surface of a Soldanella alpina leaf. Maximum and minimum values are shown on the graph. The amplitude of the greatest thermal variation is 32°C between night and day and 15°C during the same hour. The photon flux density can vary from 2000 µmol m-2s-1 over the course of an hour. Right: photos of Soldanella alpina showing the installation of temperature and light sensors [Source: Diagram © Peter Streb and Constance Laureau, unpublished; Photos © Constance Laureau]
During the growing season, the temperature of the leaves of alpine plants can vary by 30°C between night and day, and by 15°C during the same time of day (Figure 5). Thus, the rate of biochemical reactions can vary by a factor of 8 between night and day and 3 during the same hour in a leaf. In summary: at certain temperatures, the light energy captured by the leaf is not entirely consumed by biochemical reactions.

For example, the glacier buttercup, under light providing 2000 µmol photons m-2s-1, fixes about 15 µmol CO2 m-2s-1 at 23°C (see Figure 5 for the order of magnitude of the luminous flux), and only fixes half of it when it is at 10°C. In the first case the light is not saturated and the fixation of CO2 can eliminate the energy it provides, in the second case, however, the fixation of CO2 is already saturated under 500 µmol photons m-2 s-1 and therefore the light is largely excess [8].

4.2. Light

Like temperature, light can change suddenly by several orders of magnitude during the same day in alpine conditions (Figure 5). Under cloudy sky, the average light intensity is not very different between valleys and high altitude [3]. On the other hand, the maximum light intensity in clear weather is much higher at high altitude, exceeding the photosynthetic capacity of most plants.
Just like a drop in temperature, very strong light causes an excess of energy in the leaves that can damage photosystems [7]. In addition, there is more ultraviolet radiation (UVA and UVB) at higher altitudes [9], which can directly impact cellular structures: photosystems, but also DNA in the chloroplast, mitochondria and nucleus (see Cellular impact of solar UV). At the PSII level, manganese, which is involved in oxygen production (Figure 4), and plastoquinone, which transports electrons between the PSII and cytochrome b6/f (cytb6f), directly absorb UV radiations and in this way their function can be blocked [10].

A shade plant takes advantage of the moderate light intensities, which are common in the Alps, but is stressed if the light intensity is too high. On the other hand, a sun plant is more tolerant to high light intensities, but does not use weak light as well [11]. Finally, bright alpine plants such as Soldanella alpina, Homogyne alpina or Ranunculus glacialis (Figure 2) do not show any typical specific adaptation to low or high light [11].

4.3. Other factors

Other alpine environmental factors affect photosynthetic activity:

  • The decrease in air pressure at high altitudes, for example, reduces the availability of CO2 [7].
  • The wind – whose strength depends on the topography – increases the risk of plants drying out.
  • By promoting rustle, the slope also reduces water retention by the soil [3].

However, in case of water stress, a plant reacts by closing its stomata (specialized cells controlling the gas exchange of the leaf): this limits the supply of CO2 and slows down photosynthesis. Here again, the biochemical reactions of photosynthesis cannot consume the excess light energy received by the plant.

In summary, climatic factors (such as light, temperature, humidity) vary strongly, rapidly and with large amplitudes in the mountains. If the majority of lowland plants are exposed to such variations, they do not survive, because photosynthesis is not able to use the excess energy [7]. This excess energy can be transferred to oxygen by forming reactive molecular oxygen species (ROS) (Figure 4 and [12]). ROS are potentially very destructive molecules; they can damage not only the photosynthetic apparatus and particularly photosystem II (photoinhibitionA process by which excess light decreases the speed of photosynthesis in organisms capable of performing it.), but also the entire cell (seeThe fixed life of plants and its constraints). In the end, the plant’s photosynthetic capacity may be inhibited by ROS, and its ability to repair damage is greatly reduced [11].

4.4. What are the constraints for photosynthesis of alpine plants?

The constraints imposed by the alpine environment can be illustrated, for example, in two extreme cases.

Some alpine plants such as Soldanella alpina, Geum montanum and Homogyne alpina keep some green leaves during the winter. Photosynthesis of these leaves begins immediately after snowmelt, under conditions that combine high light intensities with high thermal gradients [7]. These alpine species must take advantage of the short period after snowmelt for their photosynthesis, because they will be shaded by the other plants a few weeks later. Inactivation of photosynthesis in extreme climates can be lethal to these plants.

However, most alpine plants do not keep their leaves in winter and must quickly mobilize their reserves to form their first leaves and ensure their development cycle for a short favourable period. The case of Ranunculus glacialis (see Figure 2), which is only found above 2200 m, shows that this can be even more complex. Indeed, in this plant, it is calculated that the reserves mobilized for leaf formation represent about 30 days of photosynthesis, which can hardly be achieved during the growing season [3]. As Ranunculus glacialis flowers need two years to mature [12], this suggests that the energy received during a single growing season is not sufficient to complete its development cycle in one year. Ranunculus glacialis cannot therefore risk inactivation of photosynthesis. Dwarfing of several alpine species can also be considered as a strategy limiting the investment of energy in the formation of photosynthetic tissues.

5. Acclimation in alpine plants

Acclimation involves responses to minimize the amplitude of variations in the physical parameters of the environment at the plant level, before they exert their negative effects at the cellular and molecular level. When these responses are insufficient, acclimation is manifested through other protections to prevent the destruction of cells or their organelles.

Alpine plants often have a particular architecture in pillows (see Figure 3), rosettes or tussocks (see Inheritance or convergence). This type of morphology puts the plants in a favourable microclimate [3] with: (1) a decrease in light intensity and UV radiation aborbed by leaf tissue; (2) an increase in moisture at the level of leaves with wind protection, limiting drying out; (3) lower temperature variations than in the surrounding air. The acquisition of this type of morphology represents a first avoidance response. Of course, the growth of these plants is much slower than that of the plants that do not form these structures: this is the price to pay.

As described above, very large thermal variations combined with high luminosity can induce photoinhibition of photosystem II and the formation of ROS.

Figure 6. Energy flow in the leaf under stress and light conditions and protective mechanisms in alpine plants. (1) Some of the radiation is absorbed in the epidermis by flavonoids, particularly UV radiation. (2) Some of the energy absorbed by the photosystems can be emitted as heat. (3) Some excess electrons may be transferred to oxygen to form water by PTOX, or ROS or consumed by photorespiration. ROS can be detoxified by the antioxidant system. (4) Synthesis of some sugars and metabolites characteristic of alpine plants. For details see also Figure 4. [Source: Diagram by Peter Streb]
Compared to lowland plants, the alpine plants we studied [7] are much more resistant to photoinhibition. To achieve this, they use different protection mechanisms, most of which also exist in lowland plants. These are avoidance mechanisms that occur at several organizational levels (for details of several protection mechanisms see Figure 4). They can be divided into two categories. “Upstream” mechanisms that avoid the too rapid arrival of energy on the reaction centres and “downstream” mechanisms that maintain the use of the electrons separated in photosynthetic reactions (i.e. ultimately the use of the light energy captured by the antennas) even under adverse conditions (see Figure 6).

  • Protection against UV radiation. At the epidermal level, some species synthesize flavonoidsSecondary metabolites of plants, all sharing the same basic structure. With several thousand compounds, flavonoids are the most important category of polyphenols and represent a gigantic family of antioxidants. Flavonoids are responsible for the brown, red and blue tones of flowers and fruits., pigments that absorb high-energy UV radiation. Thus, UV does not excite the underlying cells. This flavonoid screen thus protects the photosystems and prevents the destruction of the DNA of chlorophyll-containing parenchymesTissues composed of chlorophyll cells containing many chloroplasts. As the site of photosynthesis, they participate in nutritional functions. They represent an important part of the inside of the leaves.. In Soldanella alpina, for example, protection by high flavonoid contents is induced by strong light and increases with altitude [13].
  • Re-emission of the excess energy absorbed. Light collecting antennas change conformation in illuminated plants; at the same time, some of the excited chlorophylls pass their energy to carotenoids (zeaxanthin for example). This allows some of the light energy to be dissipated as heat (Figure 4). In this way, the amount of energy arriving at the reaction centres is controlled. Under excess light, the thermally dissipated light fraction is higher than that directed towards the reaction centres. Thermal dissipation is a quick way to remove the excited states of chlorophyll. However, while in some alpine species, such as Soldanella alpina and Geum montanum, this avoidance mechanism is very effective, in others, such as Ranunculus glacialis, it is not very effective and other mechanisms are activated (see below) [7].
  • Energy transfer to alternative acceptors via an electron flow. In chloroplast, the alternative oxidase (called PTOXEnzyme of the membranes of the chloroplast thylacoids, which catalyzes the oxidation of the plastoquinone pool, hence its name alternative oxidase (PTOX).), connected between the two photosystems (Figure 4), accepts electrons provided by the PSII and transfers them to molecular oxygen, thus creating water. This enzyme can thus reduce electronic pressure and thus the formation of ROS under excess light. Compared to lowland plants, the content of PTOX in alpine plants is high and its concentration increases with altitude in Geum montanum [7],[8].
  • Maintaining photosynthetic metabolism at low temperatures. If the CO2 supply limits the synthesis of sugars in the second phase of photosynthesis, Rubisco catalyzes the binding of molecular oxygen to RuBP. This is the first step in photorespiration (Figure 4). Photorespiration consumes energy, in the form of (a) carbon (RuBP), (b) electrons produced during the first phase of photosynthesis and (c) ATP. The activity of photorespiration, usually negligible at low temperatures, becomes important when the latter exceeds 20°C. In Ranunculus glacialis, which does not tolerate heat, photorespiration is already active when the temperature is low [7],[8].
  • Synthesis of specific metabolites. Some alpine plants synthesize metabolites that are generally absent or present in small quantities in lowland plants. The function of these metabolites is often not understood. But their synthesis consumes part of the energy captured by the photosynthetic apparatus and can thus help to protect it. Thus, Ranunculus glacialis accumulates significant amounts of ranunculinGlucoside produced by plants such as ranunculus (Ranunculaceae). A highly unstable molecule, it is hydrolyzed into an irritating lactone: proto-anemonin and malateMalic acid salt, a dicarboxylic acid widely used in the plant kingdom and naturally present in fruit, which contributes to its pleasant taste. Malate is an intermediate of the Krebs cycle, one of the major metabolic pathways of cellular respiration in almost all living beings, and is involved in the Benson & Calvin cycle, which is part of photosynthesis. Used as a food additive, under number E296 [14]. Geum montanum contains high concentrations of methylglucoseMonosaccharide (glucose) with a methyl group (CH3)., while Soldanella alpina contains record amounts of ascorbate (vitamin C) in its leaves [15]. Ascorbate is part of the antioxidant system that protects the plant from ROS.
  • Detoxification of highly reactive forms of oxygen (ROS). Environmental constraints increase the formation of ROS, especially during the early stages of photosynthesis. In Figure 4, ROS formation is indicated at the PSI level: it is the major pathway for the formation of ROS in light. To degrade ROS to oxygen, plants use a set of enzymatic reactions with associated metabolites. In Soldanella alpina leaves, the antioxidant system is based on the presence of vitamin C and vitamin E, as well as enzymes involved in redox processes [7]. In Potentilla saundersiana, the importance of the antioxidant system of the leaves increases with altitude [16].

In short, it is a set of protection mechanisms that allow alpine plants not only to survive, but also to develop in a habitat that becomes more and more restrictive with altitude. These mechanisms complement and add up to facilitate the life of alpine plants (Figure 6).

 


References and notes

Cover image. Alpine linaria (Linaria alpina) in the Galibier schists (2600 m). [Source: Photo © Serge Aubert/SAJF]

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[3] Körner C., Alpine plant life, Springer Verlag, Berlin Heidelberg, 1999

[4] Larcher W., Kainmüller C., Wagner J., Survival types of high mountain plants under extreme temperatures, Flora, 205:3-18, 2010

[5] Lütz C., Plants in Alpine Regions, Cell Physiology of Adaptation and Survival Strategies, Springer, Wien New York, 75-97, 2012

[6] Raven P., Evert R., Eichhorn S., Biology of Plants, Sixth Edition, W.H. Freemann and Company/Worth Publishers, 1986

[7] Streb P., Cornic G., Photosynthesis and Antioxidative Protection in Alpine Herbs, In Lütz C. (Ed) Plants in Alpine Regions: Cell Physiology of Adaptation and Survival Strategies, Springer Wien New York, pp 75-97, 2012

[8] Streb P., Josse E.-M., Gallouët E., Baptist F., Kuntz M., Cornic G. (2005) Evidence for alternative electron sinks to photosynthetic carbon assimilation in the high mountain plant species Ranunculus glacialis. Plant, Cell Environment 28:1123-1135

[9] Barry R., Mountain weather and climate, Cambridge University Press, Third Edition, 2008

[10] Teramura A., Ziska L., Ultraviolet-B radiation and photosynthesis, In “Advances in Photosynthesis Vol. 5: Photosynthesis and the Environment“. Ed. N.R. Baker, pp 435-450, Kluwer Academic Publishers, Dordrecht, 1996

[11] Walters R., Towards an understanding of photosynthetic acclimation, Journal of Experimental Botany 56:435-447, 2005

[12] Ort D., Baker N., A photoprotective role of O2 as an alternative electron sink in photosynthesis? Current Opinion in Plant Biology 5:193-198, 2002

[13] Laureau C., Meyer S., Baudin X., Huignard C., Streb P. (2015) In vivo epidermal UV-A absorbance is induced by sunlight and protects Soldanella alpina leaves from photoinhibition. Functional Plant Biology, 42:599-608

[14] Streb P., Aubert S., Gout E., Bligny R. (2003) Reversibility of cold- and light-stress tolerance and accompanying changes of metabolite and antioxidant levels in the two high mountain plant species Soldanella alpina and Ranunculus glacialis. J. Exp. Bot. 54:405-418

[15] Bligny R., Aubert S., Specifities of metabolite profiles in alpine plants. In Lütz C. (Ed) Plants in Alpine Regions: Cell Physiology of Adaptation and Survival Strategies, Springer, Wien & New York, pp 99-120, 2012

[16] Lan Ma, Xudong Sun, Xiangxiang Kong, Jose Valero Galvan, Xiong Li, Shihai Yang, Yunqiang Yang, Yongping Yang, Xiangyang Hu, Physiological, biochemical and proteomics analysis reveals the adaptation strategies of the alpine plant Potentilla saundersiana at altitude gradient of the Northwestern Tibetan Plateau, Journal of Proteomics, 112:63-82, 2015


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引用这篇文章: STREB Peter, CORNIC Gabriel, BLIGNY† Richard (2019年8月16日), How do plants cope with alpine stress?, 环境百科全书,咨询于 2024年10月8日 [在线ISSN 2555-0950]网址: https://www.encyclopedie-environnement.org/en/life/how-do-plants-cope-with-alpine-stress/.

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