Anatomical characteristics of fusoid cells and vascular bundles in <Emphasis Type="Italic">Fargesia yunnanensis</Emphasis> leaves

As of today, the functions of fusoid cell, and the transport and loading pathways of photoassimilate in bamboo leaves are still not clear. In this paper, the leaves of Fargesia yunnanensis from a greenhouse and the wild were respectively used as samples to analyze the anatomical characteristics of fusoid cells and vascular bundles. The results showed that the bamboo leaves from greenhouse got shorter and thinner with fewer layers of palisade parenchyma cells than those from the wild. The volumes of fusoid cells were also increased. Fusoid cells originated from a huge parenchyma cell as testified by the observed nuclei. Several fusoid cells usually formed one cell complex close to the midrib. Crystals were detected in fusoid cells but no pits or plasmodesmata on their walls, suggesting that fusoid cells had the function of regulating water. The presence of fusoid cells determined the major difference between a leaf blade and sheath. There were prominent chloroplasts with simple stroma lamellae in the parenchymatous bundle sheath cells and starch grains were also observed in these chloroplast. Photoassimilates could be transported across vascular bundle sheath via symplasmic pathways for an abundant of plasmodesmata in sheath cell walls, and transported into phloem tube by apoplastic pathway as there were no pits in the walls of companion cells and phloem tubes.     

树脂铸型法研究毛竹材细胞壁的纹孔特征

【目的】研究毛竹材细胞壁纹孔的形态、结构和分布排列等特征,揭示维管束组织细胞间的纹孔通道,为竹子生长发育机制的深入研究和竹材高效利用提供理论依据。【方法】毛竹竹条经树脂渗透、树脂固化、组织消化和清洗干燥等处理后,获得单个细胞铸型和空间范围内多个细胞连接的立体铸型网络。结合毛竹切片扫描电镜图像,研究导管、薄壁细胞和纤维细胞的纹孔特征以及细胞间纹孔对的连接和分布特点。【结果】毛竹后生木质导管纹孔具明显的纹孔缘结构,并呈较高的选择性分布,即靠近维管束几何中心位置一侧的导管壁上往往密集分布大量纹孔,而另一侧纹孔则十分稀少或基本没有。导管铸型上,纹孔口和纹孔膜分别为0. 9～2. 7μm和1. 1～3. 8μm;维管束内存在小导管且相互间以具缘纹孔对连接;维管束内薄壁细胞纹孔比基本组织中的数量多、孔径大,紧邻木质部导管的薄壁细胞,其纹孔分布尤为密集;纤维细胞上纹孔稀疏分布,纹孔小、纹孔道狭长,纤维状管胞上分布有具缘纹孔;维管束内细胞间由纹孔对进行横向和纵向连接,并进一步形成流体移动的空间网络。【结论】树脂铸型法可直接展现纹孔立体结构,客观反映特定流体在竹材内部的扩散或渗透路径,适用于毛竹材细胞壁纹孔特征的研究。     

蓝果树和喜树的茎、叶解剖特征分析

对蓝果树和喜树的茎、叶解剖结构进行研究的结果表明,蓝果树和喜树叶的解剖结构为典型的异面叶,叶表皮外具角质层,栅栏组织1层,排列紧密,海绵组织细胞间隙大;茎中维管束的大小及排列相似,茎中含有晶体,具有裂生型分泌道。蓝果树与喜树营养器官结构参数具有种间差异,蓝果树叶的栅栏组织发达,叶片较厚,主脉韧皮纤维发达;喜树茎的皮层存在环状厚壁组织,叶肉中存在晶体。     

Structure-function relationships during secondary phloem development in an angiosperm tree,Aesculus hippocastanum: microtubules and cell walls

We studied the dynamics of the cortical microtubule (CMT) cytoskeleton during differentiation of axial secondary phloem elements in taproots and epicotyls of Aesculus hippocastanum L. (horse-chestnut) saplings. Indirect immunofluorescence microscopy of alpha-tubulin and transmission electron microscopy revealed that fusiform cambial cells possessed a reticulum of CMTs in which individual microtubules were randomly arranged. During differentiation of these cambial cell derivatives into secondary phloem cells, the CMTs were rearranged to become helically oriented, regardless of phloem cell type. Although helical CMTs were a persistent feature of all axial elements of the secondary phloem (sieve elements, companion cells, phloem parenchyma, and fiber-sclereids), some modifications of this arrangement occurred as cells differentiated. Thus, at late stages of cell differentiation, sieve elements possessed nearly transverse CMTs, pronounced bundling of CMTs was seen in phloem parenchyma, and the density of CMTs in the helical arrays of fibers increased markedly. Additionally, phloem parenchyma possessed rings of CMTs in association with developing pit areas. Aspects of the development and chemistry of cell walls were also examined during phloem cytodifferentiation.     

竹材梯度结构对弯曲力学性能的影响

竹材梯度结构对力学性能影响显著，尤其是在弯曲应力下，更呈现明显的非对称行为。文章对竹材梯度结构进行详细解析，提取了维管束形状、纤维鞘面积、维管束梯度变化规律等多个梯度因子，然后对其弯曲力学性能进行测试，解析竹材梯度结构因子与弯曲力学性能之间的关系，阐明梯度结构对弯曲力学的影响机制。结果发现，毛竹维管束沿径向梯度分布的曲线属于下凹型曲线，梯度分布指数n=2.28；从竹青到竹黄，维管束长径比呈现明显下降的趋势，靠近竹青侧的维管束长径比较大，靠近竹黄侧的维管束长径比较小，形状更趋近于圆形；对比了竹黄侧加载和竹青侧加载2种模式下的竹材弯曲力学性能，当竹青侧受压、竹黄侧受拉的情况下，竹材的弯曲韧性最好；当竹青侧受拉、竹黄侧受压的情况下，竹材的弯曲模量最大。     

Early stages of bordered pit formation in radiata pine

Summary The development of bordered pit sites in the cambium of Pinus radiata D. Don was studied using light and electron microscopy. No primary pit fields occur in the fusiform initials and no plasmodesmatal connections were seen in radial walls of undifferentiated cambial cells or differentiating tracheids. Thin areas bounded by a thick rim appear in the radial walls of these cells once enlargement is under way. They appear to result from a redistribution of wall material which, it is suggested, is brought about by some agent which penetrates the primary wall. The thin areas, which are the sites of bordered pits, are common to the cells joined by the affected wall, and the rim which protrudes symmetrically into each cell provides a template on which the border is subsequently formed. This mechanism would explain how symmetrical pit pairs can be formed in the absence of plasmodesmata.     

竹材结构的防腐

由于在露天环境中遭遇生物腐蚀,竹秆的持久性差,所以需要采取化学手段增强其耐力.但是它的解剖构造使化学物质难以像木材那样容易进入竹材.竹秆的外部由其表皮保护防水,不像木材那样有径向渗透的途径.而其内部腔隙也有保护性纤维.化学物质的主要渗透途径位于竹秆根部微管束的后生木质部.这些渗透途径分布于横剖面,很不均匀,且少,只占总面积的8～10%,而且在通过竹节时改变方向.由于在采伐时砍伤竹秆,通向导管的细胞腔被堵塞,渗透途径也受影响.周围的薄壁细胞是竹秆组织的主要部分,它们通过微小的纹孔互相连接,只能通过弥散进入.它们所含的淀粉是昆虫和某些真菌的食品.对纤维的保护也有赖于弥散.用化学物质进行保护,对于新鲜的含水量高的竹秆效果最好.就像简单的根部处理,或技术性较强的细胞液改善.新鲜竹秆的薄壁组织和纤维也能通过垂直弥散的方法得到保护.如进行滴渍和浸渍工作,最好在竹材含水分时劈开,因为薄壁组织容易接受弥散.技术措施如竹秆的水分储存和熏蒸的过程,与竹秆的自然结构,尤其是薄壁组织有关.     

碱液处理对改善竹束液体渗透性能的研究

竹材液体渗透性是影响竹材改性处理效果的重要因素。采用碱液处理(80℃,质量分数1%～4%,处理时间1～4 h)竹束,分析工艺参数对竹束质量损失率、染液质量增加率的影响,解析处理前后竹材微观构造、孔隙结构参数的变化情况,揭示碱液处理改善竹材液体渗透性的机理。结果显示,碱液质量分数及处理时间对竹束质量损失率影响显著。碱液质量分数2%、处理时间1 h条件下,可以在保证竹束液体渗透性改善效果和处理效率的同时,使竹束质量损失率较小。扫描电镜观察发现,碱液处理后竹束导管等细胞产生明显皱缩,导管壁上规则的网状孔隙结构产生破坏,竹材部分闭塞孔隙结构重新打开,竹纤维产生剥离现象。压汞测试分析发现,碱液处理后竹材显微构造变化会导致竹束内部孔体积增大;细胞壁内部孔径40 nm左右的孔隙增多,孔径增大。竹束纤维细胞剥离可增加液体渗透通道,缩短液体渗透路径,降低液体渗透压,提升液体渗透效率。孔体积的增大导致流体在竹束内部的渗透量增大,孔径增大导致流体在竹束内部渗透的效率提高。竹束细胞壁内部小尺寸孔隙的增加,使流体有更多的渗透路径向细胞壁内部渗透,易于实现深度均匀渗透。     

桉树插条生根解剖研究*

对刚果１２号Ｗ５、雷林１号８０５１、尾叶桉插条生根解剖研究证明：桉树插条内未见潜伏根原基，必须用各种技术措施才能诱导生根。从维管形成层、韧皮薄壁组织细胞、韧皮射线、困射线、愈伤组织以及由维管形成层、韧皮射线、韧皮薄壁组织细胞组成的复合组织等部位都可产生诱导根原基；在适宜的环境条件下，诱导根原基可分化成不定根。即皮部生根和愈伤组织生根。     

Surface deterioration of moso bamboo (<Emphasis Type="Italic">Phyllostachys pubescens</Emphasis>) induced by exposure to artificial sunlight

The effect of ultraviolet-visible light irradiation on changes in surface chemistry and morphology of moso bamboo (Phyllostachys pubescens Mazel) was investigated. Fourier transform infrared (FT-IR) and FT-Raman spectroscopy were used in combination to study chemical changes induced by exposure to artificial sunlight (xenon lamp) for up to 160 h, and the resulting physical changes of cell walls of bamboo surfaces were examined by scanning electron microscopy (SEM). FT-IR results showed that significant changes occurred in the lignin component as indicated by considerable decreases in the intensities of the characteristic aromatic lignin peak at 1512 cm⁻¹ and other associated bands. This was accompanied by formation of new carbonyl groups at 1735 cm⁻¹, resulting in photooxidation of bamboo surfaces. The photosensitive nature of bamboo lignin was also demonstrated by FT-Raman analysis, in which obvious decreases in intensities of Raman bands at 1604 and 1630 cm⁻¹ mainly derived from lignin and free and esterified p-coumaric and ferulic acids were observed. SEM micrographs of the irradiated cross sections of bamboo revealed that significant damage occurred to the fiber walls, whereas the parenchyma cells exhibited slight distortion and some cracks occurred in the cell walls. The structures of cell corners and middle lamellae were nearly intact after irradiation.     

Water adsorption properties of bamboo in the longitudinal direction

Differences in the water adsorption properties of moso bamboo (Phyllostachys pubescens) were examined by analyzing the isotherms. Hygroscopicity decreased from the bottom to the top of the culm, and this tendency was marked above about 80% relative humidity. Results of alkali extraction and the analysis of bundle sheath distribution revealed that the distribution of hygroscopic saccharides, for example, hemicelluloses and less-hygroscopic vascular bundles, affects the hygroscopicity, which varies depending on the position of the internode.     

Effects of foliar potassium concentration on morphology, ultrastructure and polyamine concentrations of Scots pine needles

We examined the effects of three foliar potassium concentrations (high, intermediate and low) on the morphology, ultrastructure and polyamine concentrations of current-year and 1- and 2-year-old needles of 30-year-old Scots pine (Pinus sylvestris L.) trees. Foliar K concentration had only a slight effect on needle morphology. The sclerenchyma cell walls were thinner, the xylem area was larger, and the resin ducts were smaller in needles with a low K concentration than in needles with a high or intermediate K concentration. In addition, the bundle sheath cells were collapsed in needles having a low K concentration. The secondary growth of phloem tissue and the mesophyll area were greater in needles with a high or intermediate K concentration than in needles with a low K concentration, possibly indicating greater production of photoassimilates in these trees. At the ultrastructural level, mesophyll cells with enlarged central vacuoles and small vacuoles containing electron-dense material were common in needles having a low K concentration. Enlargement of the central vacuole coincided with an exponential increase in putrescine concentration in needles with a low K concentration, suggesting that the central vacuole may function as a storage site for putrescine.     

毛竹和重组竹腐朽前后的表面颜色及耐腐性能

以毛竹和重组竹为研究对象,用绵腐卧孔菌(PV)、密粘褶菌(GT)两种褐腐菌和彩绒革盖菌(CV)、变色栓菌(TV)两种白腐菌进行腐朽试验,比较分析了毛竹和重组竹腐朽前后表面视觉性质及其质量损失差异。结果发现:毛竹和重组竹颜色均发生了显著变化,主要表现为明度(L~*)降低,色度值(C)、红绿轴色品指数(a~*)和黄蓝轴色品指数(b~*)显著增大,其中绵腐卧孔菌对毛竹及重组竹的色差影响最大。重组竹(耐绵腐卧孔菌)能达到Ⅰ级强耐腐水平;毛竹(耐绵腐卧孔菌)和重组竹(耐密粘褶菌和彩绒革盖菌)达到了Ⅱ级耐腐水平;毛竹(耐密粘褶菌、彩绒革盖菌和变色栓菌)和重组竹(耐彩绒革盖菌)为Ⅲ级稍耐腐水平。整体来看,重组竹对白腐菌和褐腐菌的耐腐效果好于毛竹。绵腐卧孔菌虽然对毛竹和重组竹的降解能力最弱,但对其颜色变化的影响却最大。扫描电镜可观察到彩绒革盖菌通过毛竹导管壁上的纹孔进入薄壁细胞、伴胞等,同时通过分泌木质素酶导致其细胞壁降解。     

云南箭竹3种变型的叶解剖结构与生理特性

为探明云南箭竹不同变异类型的叶解剖结构与生理特性,选择云南箭竹3种变型(云南箭竹原变型、“香笋竹”“脱毛昆明实心竹”)的叶片为实验材料,采用石蜡切片技术观察叶片解剖结构,利用苯酚硫酸比色法测定相关生理指标及其光合参数。结果表明,3种变型的竹叶,在叶长、叶宽、长宽比及叶面积等方面差异显著,“香笋竹”的叶片更宽、更大;在叶片表皮层、角质层厚度、泡状细胞复合体和梭形细胞面积、维管束面积和叶脉间距离、气孔密度等方面,均表现为“香笋竹”>原变型>“脱毛昆明实心竹”;叶净光合速率和蒸腾速率中,“香笋竹”要显著高于原变型和“脱毛昆明实心竹”;在竹叶可溶性糖含量和淀粉含量方面,表现为“香笋竹”>原变型>“脱毛昆明实心竹”。云南箭竹3种变型的竹叶,在叶解剖指标上差异显著,其叶片的形态和解剖结构特征在讨论种下分类阶元水平上具有一定的分类价值。3种云南箭竹变型中,鉴于“香笋竹”的光合能力和抗逆性较强,更适合推广种植。     

Effect of sweetpotato whitefly, <Emphasis Type="Italic">Bemisia tabaci</Emphasis> (Homoptera: Aleyrodidae) infestation on eggplant (<Emphasis Type="Italic">Solanum melongena</Emphasis> L.) leaf

The nature of damage of sweetpotato whitefly, Bemisia tabaci (Gennadius) B biotype was investigated at the vegetative stage on eggplant (Solanum melongena L., family Solanasae, variety Baiyu) under laboratory conditions (temperature 25 ± 1°C, RH 70 ± 10% and photoperiod 12 h L:12 h D). The investigations were carried out after completing one generation of whitefly on the basis of morphology, physiology and anatomy of eggplant leaf. Significant differences were observed on three morphological parameters—leaf area, leaf fresh weight, and leaf dry weight. The reduction percentages of these three parameters were 26.6, 21.8 and 19.27%, respectively. Significant differences were also observed on two physiological parameters—chlorophyll content and rate of photosynthesis. The reduction percentages of these two parameters were 9.7 and 65.9%, respectively. There were no damaged tissue observed in the epidermis and mesophyll, but there were some damage tissue observed in the vascular bundle of infested leaf. There were no damaged vascular bundles observed in the control leaves. The non-damaged vascular bundles contained both xylem and phloem; while some damaged vascular bundles contained either xylem or phloem. Associated with the non-damaged vascular bundles on whitefly infested leaves were two settled whitefly nymphs apparently deriving nutrition from phloem sap. After one generation of whitefly infestation, the number of damaged and non-damaged vascular bundles of eggplant leaf was significantly different.     

软木细胞壁结构及其主要化学成分研究进展

介绍了软木细胞的形态特征,综述了国内外学者在软木细胞壁结构及化学组成方面的研究进展。软木细胞壁具有明显的层次结构,褶皱是软木细胞壁的一个主要特征,胞间连丝是跨越细胞壁之间透镜状通道。软木细胞壁主要化学成分有软木脂、木质素、多糖、抽提物和灰分,归纳总结了不同学者对各成分的测定结果以及各成分中单体的提取制备、分析鉴定结果,并提出软木细胞壁今后的研究方向。     

果树果实细胞超微结构研究进展

从细胞超微结构综述了仁果类、核果类、浆果类果树果实的薄壁细胞、筛管伴胞（SE／CC）复合体、韧皮薄壁细胞及各种细胞器的研究进展,并对果实细胞超微结构的发展方向提出了自己的看法和建议。     

Locating the initial in the vascular cambium of Pinus strobus L. by electron microscopy

Summary The results of this investigation by electron microscopy on the vascular cambium in Pinus strobus L. confirm the results of earlier investigations by light microscopy. First, they showed that differences in the thickness of tangential walls of cambial cells exist and that these differences permit grouping of cells according to the sequence of the previous divisions of the initial. This, in turn, permits the site of the initial cell in the cambial zone to be deducted. The thicker distal tangential wall of the initial in the successive series of tissue production allows for precluding the direction in which the initial function proceeds, toward the xylem or toward the phloem. Second, it was demonstrated that immature xylem cells exist in groups of four, that immature phloem cells exist in pairs, and that at all times more cells are produced toward the xylem than toward the phloem. Third, it was shown that the extra-thick tangential wall in immature xylem serves as a landmark to signal the changeover in the initial function from phloem to xylem production.     

Anatomical observations of Pseudomonas savastanoi on Rhamnus alaternus

Buckthorn (Rhamnus alaternus) was recently reported as a new host of Pseudomonas savastanoi. The main symptom on buckthorn is the formation of knots on stems, branches and occasionally on leaves. Knot formation and anatomical changes in host tissues induced by P. savastanoi were studied macroscopically and by light microscopy. Inoculation of buckthorn shoots with P. savastanoi initiated small green swellings that developed into normal size knots. The pathogen invades intercellular spaces of parenchyma tissues degrading cell walls and resulting in extensive cavities filled with bacterial cells. Many host cells contiguous to such cavities were plasmolysed and necrotic. Depending on the depth of the inoculation wound, parenchyma, cambium, ray parenchyma, and pith cells close to bacterial cavities enlarge and proliferate forming the fully grown knots. At later stages of knot development, the cambium appears dispersed in the knot and forms unoriented vascular tissues. Periderm surrounds bacterial cavities and outer layers of knots. These findings on buckthorn are compared with those reported to be caused by the same pathogen on ash, oleander and olive.     

Study of the transverse liquid flow paths in pine and spruce using scanning electron microscopy

Samples of pine (Pinus sylvestris) and spruce (Picea abies) were impregnated with a low-viscous epoxy resin using a vacuum process. The epoxy was cured in situ and the specimens sectioned. Deposits of the cured epoxy was then observed in the wood cavities using a scanning electron microscope. The investigation concentrated on tracing the transverse movements of a viscous liquid in the wood, and special attention was therefore given to the cross-field area between ray cells and longitudinal tracheids. A damage hypothesis is proposed based on the results obtained in the present investigation in combination with those from earlier studies on linseed oil-impregnated pine: In addition to the morphology of the bordered pits, viscous liquid flow in wood is dependent on damage that occurs during the impregnation procedure. For pine sapwood, liquid flow is enabled through disrupted window pit membranes, which divide the longitudinal tracheids and the ray parenchyma cells. A mechanism accounting for the reduced permeability of pine heartwood is believed to be deposits of higher-molecular-weight substances (extractives) in the ray parenchyma cells and on the cell walls. In spruce the thicker ray cells in combination with the smaller pits, which are connected to the longitudinal tracheids, reduce permeability considerably.