Knowledge Resource Center for Ecological Environment in Arid Area
| 短命植物团扇荠和柱毛独行菜在高光环境下的高效光合作用机理研究 | |
| 其他题名 | Study on mechanisms of high efficient photosynthesis of spring ephemeral Berteroa incana and Lepidium rederale under high light conditions |
| 涂文凤 | |
| 出版年 | 2012 |
| 学位类型 | 博士 |
| 导师 | 杨春虹 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 短命植物(Ephemerals)是一类生长在荒漠地带或中生落叶林下的生活周期或年生长期很短的特殊植物类群的总称，在生态系统中具有重要作用。为了适应严酷的生长环境，短命植物具有诸多特殊生理特性，高光合效率是其中之一。虽然已有研究报道多种短命植物在高光强条件下具有高光饱和点和高光合效率，但是短命植物光合作用适应高光强条件的内在机制还不清楚，而研究短命植物在高光条件下保持高光合效率的机制有利于阐明植物在极端生境下的生存策略。为了研究短命植物的光合作用适应高光强条件并保持高光合效率的机理，本文选取两种分布于准噶尔荒漠的十字花科早春短命植物(团扇荠和柱毛独行菜)为材料，并用模式植物拟南芥作为对照，研究了这两种短命植物在低光(LL)和高光(HL)条件下的光合特性以及相关的生理生化指标。选取拟南芥作为对照的原因有：(1)拟南芥也是十字花科植物，并且生活周期较短(7-8周)；(2)拟南芥是一种模式植物，关于拟南芥在高光下的适应机制已有广泛的研究，利于我们将其作为对照植物研究短命植物适应高光条件的机理。此外，为了研究团扇荠和柱毛独行菜在野外条件下的光合特性，本文还测定了野外更高光强下(生长期内白天光照变化范围为200-1500 µmol photons m-2 s-1)两种短命植物的光合参数。研究结果如下：\n(1) 在类囊体膜蛋白复合体的组成方面，与LL条件相比，HL条件下拟南芥的光系统II(PSII)超级复合体明显减少，而单体的PSII复合体和解离的PSII捕光色素蛋白复合体(LHCII)明显增多；与此相反，两种短命植物的类囊体膜结构在HL条件下依旧存在明显的PSII超级复合体成分，说明短命植物的类囊体膜超分子体系的组装在HL条件下没有受到明显的影响。\n(2) 在光合作用的光化学效率方面，LL条件下生长的团扇荠、柱毛独行菜光合作用的光响应曲线表现出这两种短命植物比拟南芥具有更高的光合潜力。拟南芥在HL条件下明显受到胁迫，PSII最大光化学效率(Fv/Fm)降低到0.69，而团扇荠和柱毛独行菜在同样HL条件下生长正常，Fv/Fm没有降低(0.83)，与LL条件相比，其相对电子传递速率(rETR)、PSII量子产量(ΦPSⅡ)等参数明显升高；野外条件下，团扇荠和柱毛独行菜PSII的光化学效率进一步升高。这表明两种短命植物具有在高光强条件下保持并提高其光合电子传递速率和PSII活性的能力。\n(3) 通过分析快速叶绿素荧光诱导动力学参数比较了两种短命植物和拟南芥的能量传递和电子传递过程。高光下两种短命植物具有较高的Sm值(Sm反映了使QA完全还原所需要的能量，即PSII反应中心受体侧PQ库的大小)，即其具有大的PQ库。高光下拟南芥具有较高的F0值，说明其LHCII向PSII反应中心的能量传递受到影响，而HL和野外条件下生长的短命植物中LHCII向PSII反应中心的能量传递都没有受到影响。\n(4) 在非光化学淬灭(NPQ)方面，HL条件下拟南芥的NPQ相对于LL下明显增强，其中qI提高了1.7倍，说明拟南芥中产生了明显的光抑制。而两种短命植物的NPQ在HL条件下只有少量增加，主要源于qE，qI则没有变化，说明其没有受到光抑制。野外条件下两种短命植物的qI进一步降低，说明一些光保护和修复机制被上调，防止了高光强对光合器官的破坏作用。\n(5) 林肯霉素抑制实验结合免疫印迹的结果证明团扇荠的D1蛋白在高光强条件下具有较高的稳定性，这是依靠D1蛋白的抗降解机制机制实现的。\n综上所述，我们认为短命植物团扇荠和柱毛独行菜在高光下具有较高的D1蛋白周转速率、稳定的PSII超分子复合体结构、极低的qI和较大的PQ库，这些因素都有利于短命植物在诸如高光强等严酷条件下保持高光合效率，从而为其在短时间内迅速生长发育并繁衍后代提供充足的物质和能量。 |
| 英文摘要 | Ephemeral plants (Ephemerals or short-lived plants), special groups living in desert or the floor of temperate deciduous forests, are characterized by very short-term growth rhythm and play very important roles in improving ecological environment. Ephemerals possess a variety of special physiological characteristics, one of which is the high photosynthetic efficiency, so as to acclimate to the harsh growing environments. Although studies on photosynthetic physiological parameters of various ephemerals, such as high light saturation point and high photosynthetic efficiency, have been reported, mechanisms of photosynthetic acclimation of spring ephemerals to high light conditions still remain unknown. Exploring mechanisms of the high light use efficiency of ephemerals under strong light conditions may lead to illumination of the survival strategies of the plants living in harsh envirenments. In this study we used two cruciferous spring ephemeral plants (Berteroa incana (B. incana) and Lepidium rederale (L. rederale)) in desert ecosystem of Junggar Basin, China, as materials, to investigate the photosynthetic characteristics and the related physiological and biochemical parameters of the two ephemerals growing in low light (LL) and high light (HL) conditions. Meanwhile we used mode plant Arabidopsis thaliana (A. thaliana) growing in the same conditions as reference. A. thaliana was chosen as reference plant because of the following grounds: 1) A. thaliana is also one of the species in the family Brassicaceae with short life cycle; 2) it is one of the model organisms whose mechanisms of photosynthetic acclimation to high irradiances have been extensively studied, which benefits researches on adaptation mechanisms of ephemerals. In order to study the photosynthetic characteristics of B. incana and L. rederale in their growing environments, we also studied the photosynthetic parameters of the two ephemerals in the field, where diurnal light irradiance ranged from 200 to 1500 μmol photons m-2 s-1. The main results are as follows:\nCompared with thylakoid complexes of LL-grown A. thaliana, formation of photosystem II (PSII) supercomplexes was compromised greatly and accordingly more monomeric PSII and light-harvesting complex of PSII (LHCII) were found on the thylakoid membrane of HL-grown A. thaliana. On the contrary, distinct PSII supercomplexes existed in the ephemerals under HL condition, demonstrating that the assembly of thylakoid supercomplexes of ephemerals had been only slightly affected even under HL condition.\nWhen grown in LL condition, B. incana and L. rederale had higher photosynthetic potential than A. thaliana. A. thaliana suffered from severe stress in HL condition and the maximal quantum efficiencies of PSII (Fv/Fm) decreased to 0.69, while B. incana and L. rederale grew healthily with unchanged Fv/Fm (0.83), and rETR and ΦPSII of the two ephemerals increased distinctly in HL condition compared with those of LL-grown ones. The photochemical efficiency of B. incana and L. rederale further increased when grown in the field. These data demonstrated that the two ephemerals were able to increase their electron transport rate and PSII activity in high irradiances.\nWe measured the energy transfer and electron transport in the two ephemerals by means of the rapid Chl a fluorescence kinetics. Sm represents the PQ pool in the acceptor of PSII RC because it reflects the energy needed to reduce QA completely. The two ephemerals had higher Sm when grown in HL condition, indicating that larger PQ pool existed in both ephemerals. Higher F0 in HL-grown A. thaliana suggested a reduced energy interaction between the antenna and the PSII reaction center in A. thaliana, while energy transfer from the antenna to the PSII reaction center in B. incana and L. rederale grown in HL and field condition hadn’t been affected.\nCompared with LL, non-photochemical quenching (NPQ) in HL-grown A. thaliana increased greatly, qI of which was 1.7 times higher, indicating that photoinhibition occurred in A. thaliana when grown in HL conditions. Compared with NPQ of LL-grown ephemerals, NPQ of those grown in HL conditions increased only slightly, which mainly resulted from the increase of qE and without changes in qI, indicating that they didn’t suffer from photoinhibition. The diminished qI in the field-grown ephemerals implied that some photoprotective and repairing mechanisms maybe upregulated to protect photosynthetic apparatus from harmful effects caused by extremely high irradiances.\nWe compared turnover rates of D1 protein in the lincomycin treated leaves of B. incana and A. thaliana subjecting to high irradiance by western blotting. Our results demonstrated that D1 protein was more stable in B. incana compared with that in A. thaliana and the stability of D1 protein was maintained by resistance to degradation by high irradiance and rapid repair of D1 protein.\nIn summary, we suggest that when grown in high light conditions, ephemerals B. incana and L. rederala have more stable D1 protein and PSII supercomplex structures, thus low photoinhibition occurrs. On the other hand, large PQ pools decrease the excitation pressure and facilitate the linear electron transfer through PSII. All these factors are responsible for the high photosynthetic efficiency of ephemerals in harsh environments including extremely high irradiances, to provide energy and materials for ephemerals to complete their life cycle quickly. |
| 中文关键词 | 短命植物 ; 高光 ; 非光化学淬灭 ; 光系统 ; 光抑制 |
| 英文关键词 | Ephemeral High light Non-photochemical quenching (NPQ) Photosystem Photoinhibition |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 发育生物学 |
| 来源机构 | 中国科学院植物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287158 |
| 推荐引用方式 GB/T 7714 | 涂文凤. 短命植物团扇荠和柱毛独行菜在高光环境下的高效光合作用机理研究[D]. 中国科学院大学,2012. |
| 条目包含的文件 | 条目无相关文件。 | |||||
| 个性服务 |
| 推荐该条目 |
| 保存到收藏夹 |
| 导出为Endnote文件 |
| 谷歌学术 |
| 谷歌学术中相似的文章 |
| [涂文凤]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [涂文凤]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [涂文凤]的文章 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
