Electron Microscopic Studies of Spruce Needles in Connection with the Occurrence of Novel Forest Decline

Needles of four spruce trees showing different degrees of novel kinds of forest decline were investigated by electron microscopy. Green needles appearing at least superficially still intact were selected for the present investigation. Most of the mesophyll appeared to be undamaged. However, groups of atypical mesophyll cells were found close to the endodermis or the hypodermis. The chloroplasts of the apparently damaged cells were particularly affected. Changes in the matrix of the chloroplasts, i.e,. increased affinity to osmium, occurrence of extensive nests of plastoglobuli, as well as damage to the membranes, i.e. lesions in the envelope and abnormal thylakoid membranes, were observed. Signs of decomposition of other cellular structures including mitochondria were also detectable. There appeared to be a close correlation between the degree of damage at the whole tree level and the degree of damage occurring at the cellular level. It is concluded that particularly the lipids and the proteinsof, the membranes are affected by anthropogenic air pollutants and natural stressors. The altered membrane structure may for instance cause abnormal osmotic conditions for the cellular compartments and may impair transport processes and thus lead to lossof function not only of the cells but also of the whole needle.     

Changes in the Constitution of Thylakoid Membranes in Spruce Needles During an Open-top Chamber Experiment

The goal of the presented paper was to study the emission effects of natural air pollutants on the protein complexes of the thylakoid membrane. The tests were carried out in the frame of a long-term experiment in which spruce trees kept in open-top chambers with unfiltered ambient-air were compared to spruce trees in chambers with purified-air. The reaction centres of photosystem I (P-700), cytochrome f, cytochrome b-563, cytochrome b-559, as well as the oxidation speed of the antennae chlorophylls were quantified. The concentrations of the cytochromes f and b-563 indicate a marked annual rhythm with decreased concentrations during the summer months. The spruce trees in chambers with ambient-air showed a smaller amount of the studied redox components in relation to 1000 molecules of chlorophyll than did the spruce trees in chambers exposed to purified-air. In addition, increased oxidation speed of antennae chlorophylls could be observed on the isolated thylakoid membranes of the spruce trees in chambers with ambient-air conditions. A relationship between the oxidation speed and the ozone concentration of the ambient air could be observed, i.e. with increasing ozone levels the oxidation of the antennae chlorophylls accelerated. However, the damage occurred only with a temporary delay (the so-called memory effect). In case of the cytochromes f and b-563 (components of the cytochrome b₆f-complex), a chamber effect related to changed light conditions became obvious when comparing spruce trees kept in chambers to trees left in their natural surrounding. The reduced photosynthetically active radiation — it is reduced in the chambers by 10 ? 30% — led to a decrease of both cytochromes. In spite of the effects due to the chambers, the results indicate that ozone could be an effective damage factor and this will be of importance with regard to the situation in the low mountain range of Germany.     

Responses of Photosynthesis,Carbohydrates and Antioxidants in Needles of Norway Spruce to Slow and Rapid Changes in Ozone

The goal of the present study was to examine the effects of slow and rapid changes of ozone (O₃) concentrations on the physiological behaviour of current-year needles of Norway spruce (Picea abies (L.) Karst.). For this purpose five-year-old spruce seedlings were exposed in growth chambers for 49 days to either charcoal-filtered air, slowly increasing O₃ concentrations from zero up to 100 nl I^?1 in weekly steps of 25 nl I^?1, or immediately to 100 nl I^?1 of O₃. During the investigation period gas exchange, carbohydrate and antioxidant contents of the current flush were measured. In needles which experienced slowly increasing O₃ concentrations, cumulative O₃ uptake was approximately 30 % lower than in needles continuously fumigated with 100 nl I^?1 of O₃. The higher 0₃ uptake in the permanent 100 nl I^?1 O₃ treatment caused a pronounced decline in net photosynthesis, in the efficiency of CO₂ uptake and in the starch content of the seedlings. Initially the ascorbate pool increased, but after 5 weeks of exposure ascorbate concentrations declined and were comparable to values obtained in charcoal-filtered controls, while the thiol contents were enhanced during fumigation with permanent 100 nl I-^?1 O₃. On the contrary, slowly increasing O₃ caused a significant increase in total needle ascorbate throughout the fumigation period, which probably prevented an O₃-induced decline in the photosynthetic machinery as photosynthesis was not affected although the thiol contents were not enhanced. Furthermore, starch content was slightly higher than in O₃-free controls. These results suggest that seedlings of Norway spruce have the possibility to acclimate to O₃ stress, as slowly increasing O₃ concentrations seemed to increase resistance and the seedlings were able to compensate.     

Absorption of Atmospheric NO2 by Spruce (Picea abies) Trees. III. Interaction with Nitrate Reductase Activity in the Needles and Phloem Transport

In order to compare the effects of excess pedospheric and atmospheric nitrogen supply on nitrate reductase activity (NR. EC 1.6.6.1) excised spruce branches were exposed to nitrate solutions or were fumigated with NO₂. Immersion of spruce branches in 6 mM nitrate caused an increase in NR activity by a factor of 14 or 19 in current-year and in one-year-old needles, respectively, as compared to controls incubated in tap water. Exposure to 65 nl I^?1 NO₂ increased NR activity by a factor of 1.5 in current-year needles and by a factor of 2.5 in one-year-old needles as compared to non-fumigated controls. Addition of cycloheximide (0.17 μM) or puromycin (200 μM) to the incubation solution prevented the induction of NR activity from both nitrate and NO₂ exposure. This finding indicates that induction of NR activity by both atmospheric NO₂ or increased nitrate supply of the needles is both caused by de-novo synthesis of NR protein. The increase in NR activity in needles of branches still attached to the tree as a consequence of exposure to 65 nl I^?1 NO₂ was found to be a transient phenomenon. The increase persisted for several days only and was no longer observed after one week of sustained NO₂ exposure. An interruption of phloem transport by girdling, applied subsequent to the induction of NR activity by atmospheric NO₂, prevented the decrease in NR activity. Apparently, export out of the exposed needles and phloem transport within the stem are involved in the regulation of NR activity upon NO₂ exposure.     

3个香蕉品种的果实淀粉形状与含量及风味物质比较

采用扫描电子显微镜对巴西蕉、宝岛蕉、红香蕉3个品种(AAA基因型)的淀粉颗粒形状及大小进行观察,并测定果实中总淀粉、直链淀粉、支链淀粉及风味物质的含量,以揭示不同品种间香蕉果实品质差异的内在机理。结果显示:(1)巴西蕉、宝岛蕉、红香蕉淀粉颗粒的形状分别为不规则三角形、圆形、棒形,大小分别为8.20~35.70μm、6.90~29.80μm、5.47~23.80μm。(2)巴西蕉、宝岛蕉、红香蕉总淀粉含量分别为(66.93±2.48)%、(90.38±2.46)%、(48.91±2.49)%;直链淀粉含量分别为(20.48±1.09)%、(21.48±1.08)%、(14.67±1.10)%;支链淀粉含量分别为(46.45±1.85)%、(68.90±1.25)%、(34.24±1.45)%;且3个品种总淀粉、支链淀粉及直链淀粉含量差异均达到显著水平。(3)巴西蕉、宝岛蕉、红香蕉Vc含量分别为(15.54±1.10)、(17.63±1.14)、(16.76±1.03)mg/100g FM;可溶性固形物含量分别为(15.50±0.22)%、(15.67±0.30)%和(16.17±0.30)%;糖/酸比分别为2.75∶1、2.74∶1、3.15∶1;差异显著性分析发现,3个品种Vc及可溶性固形物含量差异分别达到极显著、显著水平;巴西蕉和宝岛蕉糖/酸比差异不显著。研究认为,同一基因型(AAA)不同品种香蕉果实的淀粉形状、大小、总淀粉、直链淀粉、支链淀粉以及Vc和可溶性固形物含量均存在明显差异,为解释不同品种间香蕉果实品质差异提供了理论依据。     

竹子节部“韧皮部结”的发育与超微结构

研究了中国最为重要的经济竹种毛竹（Ｐｈｙｌｌｏｓｔａｃｈｙｓ ｅｄｕｌｉｓ （Ｃａｒｒ．）Ｈ．ｄｅ Ｌｅｈａｉｅ）节部“韧皮部结”的个体发育、构成该结构细胞的形态学特征及其超微结构,探讨了该结构可能的生理功能。“韧皮部结”的发育直接来源于原形成层,发生在维管束分叉处,一般成对出现。“韧皮部结”外形呈纺锤体状,一般由４～６层细胞形成叠生构造。构成“韧皮部结”的细胞可以区分为两类,一类是位于纺锤体中部     

苹果果实韧皮部及其周围薄壁细胞的超微结构观察和功能分析

利用透射电镜技术,对发育过程中的苹果（Ｍａｌｕｓ ｄｏｍｅｓｔｉｃａ Ｂｏｒｋｈ）果实韧皮部及其周围薄壁细胞的超微结构进行了观察研究。结果表明,在主脉和细脉的筛分子（ＳＥ）和伴胞（ＣＣ）之间存在胞间连丝,胞间连丝在筛分子一侧是单通道,在伴胞一侧呈多分枝通道。在细脉中筛分子小,伴胞大,在主脉中则是筛分子大,伴胞小。伴胞内胞质和核质稠密,富含线粒体、内质网和高尔基体,液泡内往往呈现多膜包被的囊泡结构,     

竹子节部“韧皮部结”的发育与超微结构

The development, cytological characters and ultrastructure of phloem ganglion in the nodal region of Phyllostachys edulis (Carr.) H. de Lehaie, a most economically important bamboo, were investigated and the possible physiological function of this special structure was proposed. The phloem ganglion derived directly from procambium is situated at the sites where the vascular bundle forks and is present in pairs. The phloem ganglion is spindle-like in appearance and usually consists of 4 to 6 layers. Two kinds of cells in the ganglion could be distinguished. In the middle, there are two layers of filiform cells with pointed ends so that there are no normal sieve plates. Nevertheless, there are many pits on the lateral wall of the filiform cells. The other type of cells located at both ends of the spindle which possess an intermediate form between the filiform cell and the normal sieve tube. The walls of these cells towards the filiform cells are strongly convex forming a special sieve plate. Ultrastructure study showed that cells in the ganglion are connected by enriched plasmodesma. During early differentiation, the paramural body and the ingrowth of cell wall could be observed. It indicates that the cells of phloem ganglion have the character of transfer cells. The organelles in the mature cells are mainly plastids with abundant accumulation of proteins of crystalline structure. The above-mentioned results suggest that the physiological function of the phloem ganglion is closely related with substance transport.      

Experiments on the control capacity of stomata of Picea abies (L.) Karst. after fumigation with ozone and in environmentally damaged material

Abstract. With the aid of specifically designed potometer experiments, it is shown that, after ozone fumigation, twigs transpiring in gas exchange chambers show poor water balance in decreasing humidity. The quotient of water uptake to water loss never falls below 0.9 in healthy material because of the control capacity of the stomata. In twigs from a tree fumigated with ozone irregular and delayed stomatal closure results in values of < 0.5 or even lower, depending on the degree of damage. As a result, in dry air, the transpiration rates of fumigated twigs often fall far below those of the control material, even if they were higher than the latter in humid air. In analogous experiments, the difference in behaviour between twigs of densely ('healthy') and sparsely needled ('damaged') trees from the natural stand is comparable to the difference between controls and ozone-fumigated trees in most respects. In soil that is more or less dried out and after the best possible saturation of the twigs during the night, the transpiration rates of fumigated trees increase fairly strongly in the humid chamber air at dawn, but finally decrease more or less suddenly to lower values than in the controls. The results are placed in the context of the basic research on plant water relations and compared with histological changes in the stomatal apparatus after a period of fumigation as described earlier. Therefore, long-term effects of pollution can be explained as a specific distrubance of hydroregulation.     

甘薯薯干高淀粉资源的鉴定及综合评价

通过对332份新征集甘薯品种资源薯干粗淀粉含量的分析测定,鉴定得到58份高淀粉种质资源。通过烘干率测定,得到36份兼具高干的高淀粉种质资源。通过抗病性、时逆性鉴定,得到5份兼抗多病的优异高淀粉品性种质资源,5份兼具耐旱性的高淀粉种质资源,29份兼具耐贮性的高淀粉种质资源。     

Chlorophyll a Fluorescence Response of Norway Spruce Needles to the Long-Term Effect of Elevated CO2 in Relation to Their Position Within the Canopy

The long-term impact of elevated CO₂ concentration on photosynthetic activity of sun-exposed (E) versus shaded (S) foliage was investigated in a Picea abies stand (age 12 years) after three years of cultivation in adjustable-lamella-domes (ALD). One ALD is supplied with either ambient air [ca. 350 µmol(CO₂) mol^–1; AC-variant) and the second with elevated CO₂ concentration [ambient plus 350 µmol(CO₂) mol^–1; EC-variant). The pronounced vertical profile of the photosynthetically active radiation (PAR) led to the typical differentiation of the photosynthetic apparatus between the S- and E-needles in the AC-variant estimated from the irradiance-responses of various parameters of the room temperature chlorophyll (Chl) a fluorescence parameters. Namely, electron transport rate (ETR), photochemical efficiency of photosystem 2, PS2 (_PS2), irradiance-saturated values of non-photochemical quenching of minimum (SV₀) and maximum (NPQ) fluorescence levels, and photochemical fluorescence quenching (q_p) at higher irradiances were all significantly higher for E-needles as compared with the S-ones. The prolonged exposure to EC did not cause any stimulation of ETR for the E-needles but a strongly positive effect of EC on ETR was observed for the S-needles resulting in more than doubled ETR capacity in comparison with S-needles from the AC-variant. For the E-needles in EC-variant a slightly steeper reduction of the _PS2 and q_p occurred with the increasing irradiance as compared to the E-needles of AC-variant. On the contrary, the S-needles in EC variant revealed a significantly greater capacity to maintain a high _PS2 at irradiances lower than 200 µmol m^–2 s^–1 and to prevent the over-reduction of the PS2 reaction centres. Moreover, compared to the AC-variant the relation between SV₀ and NPQ exhibited a strong decrease (up to 72 %) of the SV₀-NPQ slope for the E-needles and an increase (up to 76 %) of this value for the S-needles. Hence the E- and S-foliage responded differently to the long-term impact of EC. Moreover, this exposure was responsible for the smoothing of the PAR utilisation vertical gradient in PS2 photochemical and non-photochemical reactions within the canopy.     

Effect of Seed Freezing and Storage Conditions on Plasma Membrane Properties of Norway Spruce (Piceo abies Karst.) Seedlings

Norway spruce (Picea abies Karst.) seeds were frozen and stored for 15 months at + 3, ? 25, ? 75 or ? 196°C. After storage, seeds were germinated for 9?14 days to determine viability and plasma membrane protein composition, H⁺-ATPase activity and fluidity. The results indicate no significant differences in viability of seed 14 days after germination. Biochemical analyses revealed increased plasma membrane fluidity in 9-day-old Norway spruce seedlings raised from seeds pretreated at ? 75 °C. and changes in the temperature profile of membrane fluidity in seedlings after pre-treatment of seeds at ? 25 °C. On the other hand, the same treatments did not result in changes in plasma membrane protein content, protein composition or ATPase activity. There was also no difference in plasma membrane H⁺-ATPase activity assayed in the presence of different ATP hydrolysis inhibitors. Based on the presented results, and other experimental data, we suggest that during early seedling growth, adaptation of seeds to ? 25 and ? 75°C freezing and/or storage temperature results in stability of the plasma membrane protein function and composition and increased fluidity or changes in the temperature-dependent fluidity profile of these membranes.     

宁夏枸杞果实发育过程中淀粉代谢和质体超微结构研究h

该研究以宁夏枸杞为材料,对其果实发育过程中果实淀粉含量、淀粉代谢相关酶活性进行测定,并对果实发育过程中果皮细胞内质体超微结构和淀粉组织化学定位进行了系统观察。结果表明:(1)枸杞果实内淀粉含量随果实的发育呈现先增加后降低的变化趋势,在果实花后14d其含量达到最高(13.85mg·g-1)。(2)果实内α淀粉酶活性和β淀粉酶活性随果实发育成熟呈现逐渐增加的趋势,且α淀粉酶活性始终明显高于β淀粉酶活性。(3)组织化学和超微结构研究表明,在果实转色(花后24d)以前果实的造粉体内有大量淀粉粒的存在,但在果实第二次快速生长期,果实内的淀粉粒分解、消失,而叶绿体内没有观察到淀粉粒。研究认为,淀粉是宁夏枸杞果实发育过程中碳水化合物的一种暂时贮存形式,对维持果实早期的库强起到了重要作用,但随着第二次快速生长期果实库强的增加,淀粉体内的淀粉被淀粉酶分解转化为还原糖贮藏在果肉细胞中。     

利用三倍体胚乳遗传模型定位玉米籽粒淀粉含量QTL

在两种环境条件下种植以普通玉米自交系丹232和爆裂玉米自交系N04为亲本构建的259个F2:3家系群体, 采用SSR标记构建了包含183个标记的玉米遗传连锁图谱, 覆盖玉米基因组1 762.2 cM, 标记间平均距离为9.6 cM。利用三倍体胚乳遗传模型和区间作图方法对籽粒淀粉含量进行了QTL定位和遗传效应分析, 春、夏播条件下共检测到10个QTL, 春播条件下检测到的QTL在夏播均被检测到, 分别位于第1、3、4、5、7染色体上,可解释淀粉的表型总变异分别为36.84%和72.65%, 单个QTL解释表型变异介于4.74%~11.26%。在检测到的 QTL中, 有2个QTL的遗传作用方式在春播均表现为超显性, 而夏播分别为加性和部分显性; 其他2个为加性, 1个为部分显性, 5个为超显性。3个QTL的增效基因来自丹232, 其余QTL的增效基因均来自N04。     

Inhibition of photosynthesis and transpiration in relation to mercury-induced root damage in spruce seedlings

Spruce seedlings [ Picea abies (L.) Karst.] were exposed in nutrient solutions to a range of concentrations of HgCl₂ and CH₃HgCl for 7 weeks. The mineral, chlorophyll and water contents of the needles, and dry weights of root and needles were then estimated. The rates of photosynthesis, transpiration and dark respiration of the intact plants were determined using a Li-cor portable photosynthesis-measuring system. CO₂ uptake decreased as the supply of both forms of Hg increased. Rates of transpiration were significantly reduced only after exposure to CH₃HgCl. Similar concentrations of Hg were found in needles independent of the form of Hg supplied. Decreased rates of CO₂ uptake at 100 n M HgCl₂ and 1 n M CH₃HgCl could be explained by lower levels of chlorophyll, and by lower levels of chlorophyll and closed stomata at all other CH₃HgCl concentrations. Only at 1000 n M HgCl₂ were other photosynthetic parameters affected.
Decreased rates of transpiration and the lower chlorophyll levels in the needles did not appear to be due to the direct action of Hg, but rather to root damage that leads to a decrease in water supply and nutrient levels in the needles.