兜兰属与杓兰属植物的生理生态适应性
常玮
学位类型博士
导师胡虹 ; 张石宝
2010-05
学位授予单位中国科学院研究生院
学位专业植物学
摘要兜兰属(Paphiopedilum)与杓兰属(Cypripedium)同属杓兰亚科(Cypripedioideae),是世界著名的观赏兰花,也是受威胁最为严重的濒危保护物种之一。这两类植物亲缘关系较近,但地理分布、叶片性状、生长发育特性迥异,引种驯化存在较大差异。为了探讨这两类植物的生理生态适应性及其相关关系,本论文从三个方面进行研究:(1) 通过对几种兜兰属和杓兰属植物的光合生理和叶片特性方面的比较研究试图阐明由此引发的生态学和进化意义;(2) 杏黄兜兰对光照、水分及低温的生理响应及相关的适应性研究为兜兰属植物的保护和引种驯化提供理论依据;(3) 对三种杓兰繁殖生态学及不同光环境下黄花杓兰可塑性特性及保留的研究为杓兰属植物的保护和引种驯化提供理论依据。论文主要研究结果如下:1、与兜兰属植物相比,黄花杓兰与西藏杓兰为了适应高海拔地区短暂的生长季以及富养分土壤具有以下叶片特性:短叶寿命,较高的饱和光合速率(Pmax)、叶片氮含量(Na)、光合氮利用效率(PNUE)、比叶面积(SLA)、叶绿素a,b的比值(Chla/b),以及较低的叶片构建成本(CC)和叶片碳氮比(C/N)。而兜兰属植物则具有长叶寿命,低Pmax、叶肉导度(gm)但较高SLA,CC以及C/N,这些叶片特性则是为了适应石灰岩地区的低土壤养分以及低光照条件。作为与兜兰具有重叠分布区域的长瓣杓兰(C. lentiginosum)则不仅保留了杓兰属植物的遗传学特性,如较高的气孔导度(gs)、以质量为单位的饱和光合速率(Pmax-M)、PNUE 和冬季休眠;而且也发展出类似于兜兰属植物的特性,如较高的气孔相对限制值(RSL),gm,Chl a/b,较高的叶氮在捕光组分中的分配比例(PL)以及具有斑点的叶片。这些结果表明兜兰属与杓兰属植物间的趋同及趋异进化,也反应出环境对杓兰亚科植物自然选择的压力。2、随着生长时间的延长,杏黄兜兰在不同光强处理下的光合特性变化趋势有所不同。首先,在50%遮光(HL)条件下六个月时,杏黄兜兰的Pmax显著低于75%遮光(ML)和95%遮光条件(LL),这是由于杏黄兜兰长期适应于林下较弱的光环境中,对较高光强(50%)的初始反应是负面的—导致光合速率的降低。而对于低光强的初始适应性较强,表现出最高的Pmax。其次,更长一段时间(十二个月)以后,杏黄兜兰在HL下植株的Pmax、光饱和点(LSP)和光补偿点(LCP)都有了显著的提高,反而在ML和LL中下出现了显著的降低。而且,光照条件也影响着叶片的比叶重(LMA)、gm、氮含量(N)、叶氮分别在羧化作用、电子传递和捕光系统中的分配比例(PC, PB, PL)。杏黄兜兰的Pmax与gs、gm呈显著正相关,且HL下植株的gs、gm都有增加的趋势;HL下植株提高了氮对生物能学组分的分配(PB,PC),而降低了PL来提高了氮利用效率(PNUE)从而提高了Pmax。此外,HL中的类胡萝卜素与总叶绿素比值(Car/Chl)含量局于最高,而LL中的Chla/b最低。这些结果表明杏黄兜兰能够通过调整叶片结构、叶氮分配对不同光照强度展现出了较高的光合作用响应的可塑性;它不仅能够对较高光强采用提高Pmax的方式利用光能、耗散过多光能,而且也能忍耐非常荫蔽的环境。三种光照条件下,ML中植株开花及结实个体数最高。3、在不同供水制度下生长六个月后,杏黄兜兰的光合能力没有表现出显著性差异,但是间隔4天(HW)供水的植株Pmax低于间隔8天(MW)和间隔20天(LW)。另一方面,PSⅡ的最大光化学效率(Fv/Fm)在HW和LW中显著降低,而MW则维持在正常水平。在HW条件下,植株将更多的光能用于光合作用中的氧化循环中以及显著较高的呼吸速率(Rd)可能是导致光合速率较低的原因。MW和LW下植株能够维持较高的光合能力也得益于较多的叶氮对光合机构羧化组分和生物能学组分的分配以及杏黄兜兰叶片良好的保水性能。4、杏黄兜兰对低温是非常敏感,在4℃下生长3天时光合能力大幅度降低, 15天后几乎不能进行光合作用,而10℃和15℃的生长温度对杏黄兜兰光合能力的影响不明显。5、香格里拉四个不同生境的黄花杓兰休眠根茎移栽至昆明温室同一生境中萌发生长后表现出与原生境光环境趋势一致光合特性:道班(DB)植株的的Pmax最高,仙人洞(XRD)植株最低,天生桥(TSQ)与小中甸(XZD)居于中间且两者间差异不显著。导致DB移栽的植株Pmax显著较高的因素主要是较高LSP和PNUE。但是在比叶重(LMA)、叶氮含量及叶绿素含量等方面并没有出现显著差异。这说明在光环境变化的情况下,黄花杓兰能够从叶片结构方面表现出较为迅速的可塑性反应,但在光合特征方面则一定程度上保留了原生境的可塑性特征。也就是说黄花杓兰在较高光照条件生境下具有的可塑性在光环境发生变化后的一个生长季中仍发挥着作用,且这种作用主要是通过电子传递功能组分来实现的。6、三种杓兰在有性繁殖阶段间的光合特征有所不同。相比营养生长阶段和结实阶段,黄花杓兰和西藏杓兰在开花阶段具有更高的Pmax、最大羧化速率(Vcmax)、光饱和电子传递速率(Jmax)、磷酸丙糖利用效率(TPU)及光系统II的实际化学效率;但是紫点杓兰的光合作用在开花阶段几乎没有变化。三种杓兰的光合速率在结实阶段均有所下降。三种杓兰中紫点杓兰植株体积、总叶面积、花体积与果实体积都是最小的,而单位叶面积所承载的果实体积最大。结果表明:虽然黄花杓兰和西藏杓兰对开花的生理消耗建立了一种补偿机制来增加资源的获取,但是这种对当前繁殖器官的资源追加投入势必会减少地下根茎的贮存养分。紫点杓兰能够在整个生长期都保持一个平稳的光合能力,且具有最高的果实承载力。紫点杓兰的广泛分布可能与它的更为经济有效的有性繁殖方式有关系。综上所述,杓兰属植物与兜兰属植物光合特性及相关叶片性状反应了两者对不同生境的适应性。兜兰属植物及与其具有共同分布区域的杓兰属植物的共同的叶片特性具有应对石灰岩地区低养分和低光照环境;而位于高海拔的杓兰属植物的叶片特性则具有应对短生长季和土壤养分充足的环境。而且两者间的光合特性变化及相关叶性状的变化也表明两者间存在趋同和趋异的演化关系。杏黄兜兰对光照的适应范围较为宽泛且75%的光照有利于其开花结果;对基质的水分需求程度较低,过于频繁的供水使其表现出胁迫响应,但对低温的胁迫响应非常明显。黄花杓兰在光照环境突变的情况下表现出较好的可塑性,且原生境条件下所具有的可塑性特征仍在未来的一个生长季所保留。紫点杓兰较黄花杓兰与西藏杓兰表现出了更为经济有效的繁殖方式,这对其广泛的分布范围是有利的。我们的研究有助于深入理解杓兰亚科植物适应性进化的演化关系同时也为杓兰亚科的保护和引种驯化提供了理论依据。
资助项目Paphiopedilum and Cypripedium,known as slipper orchids in horticulture, belong to the subfamily Cypripedioideae of the Orchidaceae. Although they are closely related phylogenetically, there are significant differences in leaf traits and geographical distributions between two genera. This dissertation includes the following sections: (1) the leaf functional traits were compared in six species of the two genera; (2) the physiological responses of P. armeniacum to different water regimes, light regimes and low temperature; (3) the leaf phenotypic plastics of C. flavum in response to the different light condition and the photosynthetic characteristics of three Cypripedium species during sexual reproduction. The aims are to understand the convergent and divergent evolution between the two genera in leaf traits and their adaptive significances, and the leaf plastic responses to different levels of resources. Such information could provide scientific basis for conservation and domestication of Paphiopedilum and Cypripedium. The results are given below:1. Compared with Paphiopedilum, Cypripedium showed significantly higher photosynthetic rate (Pmax), leaf nitrogen content (Na), photosynthetic nitrogen utilization (PNUE), the fractions of leaf nitrogen partitioning in carboxylation (PC) and bioenergetics (PB), specific leaf area (SLA), ratio of leaf chlorophyll a and b (Chla/b), but significantly lower leaf construction cost (CC) and the ratio of leaf carbon content to leaf nitrogen (C/N). These leaf traits of Cypripedium are considered as the adaptation to short growing period and rich soil nutrients in the alpine habitats. Conversely, the long life span, low Pmax and mesophyll conductance (gm) but high SLA, CC and C/N in Paphiopedilum indicated that the adaptation to low-light, limited-nutrient habitat in the limestone area. As a sympatric species of Paphiopedilum, C. lentiginosum not only kept phylogenetically leaf traits of Cypripedium, suchas stomatal conductance (gs), Pmax, PNUE and dormant in winter, but also possessed many leaf traits which is similar to that in Paphiopedilum, such as relative stomatal limitations (RSL), gm, the ratio of leaf chlorophyll a and b (Chl a/b), fraction of leaf nitrogen allocated to light-harvesting components (PL). These results indicated the convergent and divergent evolution of Paphiopedilum and Cypripedium in leaf traits.2. Paphiopedilum. armeniacum exhibited a high plasticity of leaf photosynthetic function in response to different light regimes, but the responses changes with the time. Due to grow under low light habitat, P. armeniacum grown under 50% shade (HL) had the significantly lowest Pmax than the plants grown under 75% shade (ML) and 95% shade (LL) after six months. However, after twelve months, the Pmax of the plants grown under HL increased significantly and then became the highest one among three levels of light. It is also found that leaf dry mass per unit area (LMA), leaf stomatal conductance (gS), internal mesophyll conductance (gm), the fraction of leaf nitrogen partitioning in photosynthetic carboxylation (PC), bioeneretics (PB) were greatly influenced by irradiance. The plants grown under HL increased gS, gm, PC, PB to increase Pmax. In addition, the plants grown under HL had the highest ratio of total chlorophyll content to total Carotenoid content (Car/Chl) while the plants grown under LL had the lowest ratio of leaf chlorophyll a and b (Chl a/b). As a result, plasticity of leaf photosynthetic physiology of P. armeniacum in response to different light regimes depended largely on leaf nitrogen partitioning and leaf structure. As for the numbers of flowering and fruiting, ML was the best light level.3. The responses of P. armeniacum to different water regimes were not significantly different. But the Pmax and the maximum photochemical efficiency of PSⅡ (Fv/Fm) decreased with the increased frequency of watering. The reasons were that the plants have high respiration rate (Rd) and make more use of light energy to oxidation cycle. The plants watered every eight days (MW) and every twenty days (LW) had higher Pmax than the plant watered every four days (HW) mainly because of the higher PC and PB. Besides, the leaves of P. armeniacum had excellent property for holding water also contributed to the high photosynthetic capacity.4. Paphiopedilum. armeniacum was very sensitive to the low temperature. The plants significantly decreased photosynthetic capacity after grown under 4℃ for three days and the photosynthetic machinery was destroyed after fifteen days. The photosynthetic capacity of P. armeniacum exhibited no change at 10℃ and 15℃.5. Cypripedium flavum of four habitats (DB, XRD, XZD and TSQ) with different light intensity exhibited different photosynthetic characteristics after transplanted to the same environment in Kunming. Among the habitats, the light intensity of DB was the highest while XRD was the lowest. The light intensity of XZD and TSQ were not significantly difference. Among all the plants in Kunming, the plants of DB had the significantly highest Pmax but the plants of XRD had the lowest Pmax. The light saturation point (LSP) and photosynthetic nitrogen use efficiency (PNUE) agreed well with the light intensity of four habitats and contributed to the high Pmax of DB. The LMA, Chl and leaf nitrogen content were not different among all the plants. C. flavum exhibited sensitively response to the change of light in leaf construction while kept the plasticity of leaf photosynthetic characteristics which developed from its own habitat.6. The photosynthetic capacity of C. tibeticum and C. flavum were significantly increased at the flowering stage. For these two species, the significantly increased Amax were closely related to the maximum carboxylation rate by ribulose-1, 5-bisphosphate carboxylase/oxygenase (Vcmax), photon saturated rate of electron transport (Jmax), the rate of triose phosphate utilization (TPU) and actual quantum efficiency of the photosystem II photochemistry (ΦPSII) respectively. However, flowering almost did not affect the photosynthetic capacity of C. guttatum. C. guttatum had the smallest plant size, the leaf area, the volume of labellum and the volume of fruit, but the biggest fruit volume per leaf area among three species. These results indicated that for C. flavum and C. tibeticum there were a physiological mechanism in photosynthesis to compensate the cost of flowering as well as increased resource acquisitions, which would be beneficial to the survival or future flowering of the plant. C. gutattum could keep a steady photosynthetic capacity during life history. This kind of pattern could decrease the effect of the reproductive costs as much as possible. In contrast to C. flavum and C. tibeticum, C. gutattum possessed a more economical and effective reproductive pattern which maybe related to its wider distribution.In conclusion, Paphiopedilum and Cypripedium have significantly different leaf traits which agree well with their habitats and there is a divergent and convergent evolution between the two genera. P. armeniacum is much tolerant and responsive to varying water and light availability but very sensitivity to the low temperature. Confronting the suddenly change of light environment, C. flavum can respond sensitively to the change of light in leaf construction but the plasticity of leaf photosynthetic characteristics which developed from its own habitat can hold for the next growing season. In contrast to C. flavum and C. tibeticum, C. gutattum possesses a more economical and effective reproductive pattern which maybe related to its wider distribution. The study of the relationship between the two genera, the response and tolerance to the environmental factors of the two genera are important for understanding the adaptation and evolution of the Cypripedioideae.
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/16098
专题昆明植物所硕博研究生毕业学位论文
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常玮. 兜兰属与杓兰属植物的生理生态适应性[D]. 中国科学院研究生院,2010.
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