矢母根的组织发育及其与生长环境的关系

观察知母根的组织发育,发现具有典型的单子叶植物根的组织特征,特别是在同一条根中初生木质部脊数可以随机的发育而增加,同一株知母不同根之间初生木质部脊数也不尽相同;内皮层细胞壁增厚由凯氏带发育淡马蹄形,内皮层外侧１－３层皮层细胞内侧壁可以木栓化或强烈木化增厚。     

知母根的组织发育及其与生长环境的关系

观察知母根的组织发育,发现具有典型的单子叶植物根的组织特征,特别是在同一条根中初生木质部脊数可以随根的发育而增加,同一株知母不同根之间初生木质部脊数也不尽相同;内皮层细胞壁增厚由凯氏带发育为马蹄形,内皮层外侧1－3层皮层细胞内侧壁可以木栓化或强烈木化增厚,这种变化与其生长环境具有密切关系,当其移植于湿润环境中后,内皮层马蹄形增厚减弱,其外侧皮层细胞内侧壁仅发生木柱化增厚,且减弱。     

三角梅扦插育苗技术研究

以三角梅越冬枝条及当年嫩枝作试材,分别对不同植物生长调节剂种类、不同浓度处理、不同直径插条及不同扦插时期的生根效应进行研究。结果表明,NAA、IAA和ABT(生根粉)对插条具有良好的促根作用,其中以NAA 100mg/L浸泡插条基部3h效果最佳,生根率达91.7%。健壮之越冬枝条是三角梅理想的扦插材料,初夏扦插育苗效果较好。     

单子叶植物根的内皮层及其观察方法

裸子植物和具有少量次生长的双子叶植物根的内皮层细胞通常都具有径向壁和横壁加厚而成的凯氏带结构。但多数单子叶植物和少数双子叶植物(没有次生生长的种类)根的内皮层细胞只有在发育的早期(幼根)具有凯氏带,发育的后期(较老的根)内皮层细胞壁内敷贴了一整层栓质层,随后细胞壁又经过了五面加厚(只有邻接皮层一面的壁没有加厚)或六面加厚(即全部细胞壁都加厚),加厚部分都经过了木质化,因此这时就看不到凯氏带了。由于内皮层细胞内敷贴了一整层栓质层,这类植物根的维管柱似乎被一层不透水的套子所隔开了。实际不然,因为并不是全部内皮层细胞都具有五面或六面加厚的壁,通常有一部分内皮层细胞,就是在根的横切面上靠近木质部角端的那一部分内皮层细胞,仍有未栓质化、未加厚、只有凯氏带的纤维素薄壁,这一部分内皮层细胞     

黄波罗不同根序的解剖结构及其功能异质性

 细根是树木吸收水分养分的主要器官, 其生长与周转对森林生产力及生态系统物质循环具有重要的影响。为了更好地认识细根的结构特征与功能及其在根序中的分布, 采用石蜡切片方法对黄波罗(Phellodendron amurense) 1～5级根解剖结构(直径、皮层组织、通道细胞数目、维管束发育和菌根侵染等)进行了观察统计。研究表明: 细根直径、维管束直径以及维管束在根中所占的比例随根序增加而增加。1~3级根皮层层数、皮层薄壁细胞直径相近, 但总体呈减少趋势, 部分4级根有少量残留的皮层, 而成熟的5级根已经没有表皮及皮层组织。1~3级根具有通道细胞, 菌丝侵染率均较高; 4、5级根无通道细胞, 也无菌丝侵染。1、2级根是初生根, 无木栓层; 4、5级根是次生根, 具有完整的木栓层; 3级根中既有初生根, 也有次生根, 并逐渐形成木栓层。说明随根序升高, 细根吸收能力减弱, 输导能力增加, 抵御环境胁迫的能力增加, 有利于延长寿命。根据解剖结构、直径和根序的关系, 将黄波罗前3级根中直径小于0.8 mm、未形成连续木栓形成层、具有通道细胞的根定义为细根。     

勃氏甜龙竹水对高血脂大鼠降血脂作用及脂代谢相关基因表达的影响北大核心CSCD

为了开发利用资源丰富的勃氏甜龙竹水,对勃氏甜龙竹水的常规成分进行分析,并探讨其对高血脂症大鼠降血脂作用及其可能的分子机制。经对勃氏甜龙竹水进行总黄酮含量、总酚含量、总糖含量、总蛋白质含量及氨基酸含量测定,确定其总糖量为25.3%,蛋白质含量为11.4%,总酚含量为0.35%,总黄酮含量为0.085%,总氨基酸含量为8.114%,其中含有7种必需氨基酸。采用高脂饲料饲喂法建立高血脂大鼠模型,从勃氏甜龙竹下部采取竹水饲喂高血脂大鼠,在不同时间进行大鼠尾静脉采血,测定各组实验动物的血清血脂水平,并测定大鼠肝脏中与血脂代谢相关的基因mRNA相对表达量。结果发现,勃氏甜龙竹水能有效降低高血脂症大鼠的血清总胆固醇(TC)、低密度脂蛋白(LDL-C)的含量,同时能提高大鼠血清高密度脂蛋白(HDL-C)含量和肝脏LXRα、ABCA1基因mRNA的表达量。勃氏甜龙竹水能够在一定程度上降低血脂水平,预防高脂血症的发生,该作用可能与上调LXRα、ABCA1基因表达,进而促进胆固醇逆转运有关。     

勃氏甜龙竹水对高血脂大鼠降血脂作用及脂代谢相关基因表达的影响

为了开发利用资源丰富的勃氏甜龙竹水,对勃氏甜龙竹水的常规成分进行分析,并探讨其对高血脂症大鼠降血脂作用及其可能的分子机制。经对勃氏甜龙竹水进行总黄酮含量、总酚含量、总糖含量、总蛋白质含量及氨基酸含量测定,确定其总糖量为25.3%,蛋白质含量为11.4%,总酚含量为0.35%,总黄酮含量为0.085%,总氨基酸含量为8.114%,其中含有7种必需氨基酸。采用高脂饲料饲喂法建立高血脂大鼠模型,从勃氏甜龙竹下部采取竹水饲喂高血脂大鼠,在不同时间进行大鼠尾静脉采血,测定各组实验动物的血清血脂水平,并测定大鼠肝脏中与血脂代谢相关的基因mRNA相对表达量。结果发现,勃氏甜龙竹水能有效降低高血脂症大鼠的血清总胆固醇(TC)、低密度脂蛋白(LDL-C)的含量,同时能提高大鼠血清高密度脂蛋白(HDL-C)含量和肝脏LXRα、ABCA1基因mRNA的表达量。勃氏甜龙竹水能够在一定程度上降低血脂水平,预防高脂血症的发生,该作用可能与上调LXRα、ABCA1基因表达,进而促进胆固醇逆转运有关。     

菰适应湿地环境的解剖和屏障结构特征研究

菰(Zizania latifolia)是一种多年生挺水植物,为了探讨该植物根、茎和叶的解剖结构、组织化学及其质外体屏障的通透性生理。该文利用光学显微镜和荧光显微镜,对菰的根、茎、叶进行了解剖学和组织化学研究。结果表明:(1)菰不定根解剖结构由外而内分别为表皮、外皮层、单层细胞的厚壁机械组织层、皮层、内皮层和维管柱;茎结构由外而内分别为角质层、表皮、周缘厚壁机械组织层、皮层、具维管束的厚壁组织层和髓腔。叶鞘具有表皮和具维管束皮层,叶片具有表皮,叶肉和维管束。(2)不定根具有位于内侧的内皮层及其邻近栓质化细胞和外侧的外皮层组成的屏障结构;茎具内侧厚壁机械组织层,外侧的角质层和周缘厚壁机械组织层组成的屏障结构,屏障结构的细胞壁具凯氏带、木栓质和木质素沉积的组织化学特点,叶表面具有角质层。(3)菰通气组织包括根中通气组织,茎、叶皮层的通气组织和髓腔。(4)菰的屏障结构和解剖结构是其适应湿地环境的重要特征,但其茎周缘厚壁层和厚壁组织层较薄。由此推测,菰适应湿地环境,但在旱生环境中分布有一定的局限性。     

牡竹属三竹种的秆形质量与材性比较

通过牡竹属(Dendrocalamus) 3个竹笋品质佳的竹种（勃氏甜龙竹(D.brandisii)、马来麻竹(D. asper)、花吊丝竹(D. minor var. amoenus)）竹材形态质量及材性比较的研究,结果表明：种间立竹枝下高、相对全高差异显著或极显著,勃氏甜龙竹相对枝下高最小,立竹胸径、全高、枝下高、尖削度值、壁厚率均为最大;竹秆含水率随立竹年龄增大而下降,3年立竹竹秆含水率花吊丝竹>勃氏甜龙竹>马来麻竹,种间差异极显著;相对材积勃氏甜龙竹（1771.35cm 3 cm-1）>马来麻竹（1166.66 cm3 cm-1）>花吊丝竹（659.78 cm3 cm-1）,种间差异极显著;竹材密度随立竹年龄增大而提高,3a立竹竹材密度花吊丝竹（0.914 g.cm-3）>勃氏甜龙竹(0.812 g.cm-3)>马来麻竹（0.749 g.cm-3）,种间差异显著。综合分析勃氏甜龙竹、马来麻竹可作为优良的笋材兼用竹种,花吊丝竹宜作为笋用、观赏竹种推广应用。     

白鲜根的发育解剖学研究

应用半薄切片、常规石蜡切片并结合离析法,对药用植物白鲜(Dictamnus dasycarpus Turcz.)根的发生发育过程进行了研究。结果表明:白鲜根的发生发育过程包括4个阶段,即原分生组织阶段、初生分生组织阶段、初生结构阶段以及次生结构阶段。原分生组织位于根冠内侧及初生分生组织之间,衍生细胞分化为初生分生组织。初生分生组织由原表皮、基本分生组织以及中柱原组成。原表皮分化为表皮,基本分生组织分化为皮层,中柱原分化为维管柱,共同组成根的初生结构;在初生结构中,部分表皮细胞外壁向外延伸形成根毛,皮层中分布有油细胞,内皮层有凯氏带,初生木质部为二原型或偶见三原型,外始式;根初生结构有髓或无。次生结构来源于原形成层起源的维管形成层的活动以及中柱鞘起源的木栓形成层的活动;白鲜次生韧皮部宽广,其中多年生根中可占根横切面积的85%,另外除基本组成分子外,还分布有油细胞;周皮发达,木栓层厚;初生皮层、次生木质部和次生韧皮部薄壁细胞中常充满丰富的淀粉粒。     

ONTOGENETIC ANALYSIS OF TREE ROOTS IN ACER RUBRUM AND BETULA PAPYRIFERA

The development of long (6-20 m) tree roots was reconstructed from serial transverse sections taken 10-20 cm apart. Measurements of primary xylem diameter showed that the tips of long roots of red maple (Acer rubrum L.) and paper birch (Betula papyrifera Marsh.) are initially small, but they increase in diameter with increasing distance from the stem. A repeating pattern of the width of the first annual ring marks length increments of long roots. The pattern of ring width is paralleled by a pattern of primary xylem diameter. Our interpretation is that primary xylem diameter increases during spring and early summer, stays constant during late summer and decreases in autumn. After injuries to large root tips, new large lateral tips are formed that replace the parent tip. Thus, a single long root is actually formed by a succession of these replacement roots. In a series of sections there may be sudden changes in primary xylem diameter as the successive sections pass from parent root to replacement root at points of injury. These changes in birch are associated with changes in a number of protoxylem poles.     

Comparative root anatomy of papilionoid Legumes

The aims of the present study were (i) to compare the anatomical structures of roots from legume species belonging to the tribes Aeschynomeneae, Fabeae (syn. Vicieae), and Trifolieae (Papilionoideae); (ii) to characterize those developmental stages of roots that are most useful for comparative studies; (iii) to characterize root developmental patterns during their growth from primary to adult structures; and (iv) to identify developmental patterns that are typical for particular tribes within this plant group. To this end, serial transverse cuts of the main roots of 20 species belonging to the above-mentioned tribes were made from the root tip to the root collar. Vessel density, vessel diameter, secondary cortex area, and xylem area were quantified using appropriate software. Based on root ontogeny, four stages giving evidence for important developmental events were chosen based on which a comparison of the species-specific structures became possible. The first stage corresponds to the primary structure of a root. The second stage corresponds to the onset of cambium and phellogen division, when their first division products become differentiated. The third and fourth stages correspond to adult roots with a well-developed secondary structure. These developmental stages that allowed between-species comparison turned out to be useful characterising those patterns that best typify a particular tribe within the subfamily. Vessel density, vessel diameter, and the xylem transverse area were found to differ significantly between the tribes examined. Some of the analyzed morphological variables had a tribe-specific consistency, so that, together with other characteristics, they should be included in approaches to clarify systematic problems in the legume family.     

CO2浓度倍增对红松幼苗根尖和叶解剖结构及生理功能的影响

大气CO₂浓度升高对植物的影响是目前植物生态学研究中普遍关注的问题。以往的研究主要关注植物地上部分叶解剖结构及生理功能的改变, 而对根解剖结构和生理功能变化以及根与叶变化之间潜在联系的研究较少。该文以三年生红松(Pinus koraiensis)幼苗为研究对象, 通过CO₂浓度倍增(从350 µmol·mol^-1增加到700 µmol·mol^-1)试验, 研究当年生针叶和根尖解剖结构及生理功能的变化。结果表明: (1) CO₂浓度倍增处理的红松幼苗, 气孔密度显著降低, 叶肉组织面积、木质部及韧皮部面积明显增加; (2) CO₂浓度倍增导致红松幼苗根尖直径增粗, 皮层厚度和层数显著增加, 管胞直径变小; (3)高CO₂浓度处理下, 叶气孔导度和蒸腾速率降低, 光合速率和水分利用效率提高, 同时根尖的导水率显著下降, 但管胞的抗栓塞能力显著提高。这些结果显示, 叶和根解剖结构及生理功能在CO₂浓度升高条件下具有一致的响应。未来研究中应该同时关注全球气候变化对植物地上和地下器官结构与功能的影响。     

Linking root morphology, longevity and function to root branch order: a case study in three shrubs

Root branching order supports a powerful approach to understanding complex root systems; however, how the pattern of root morphological characteristics, tissue carbon (C) and nitrogen (N) concentrations, and root lifespan are related to anatomical features of variable root orders for mature shrubs (～19 years old) in sandy habitats is still unclear. In this study, these relationships were investigated for three typical shrubs in Horqin Sand Land, Northeast China. Root diameter, individual root length, tissue carbon concentration, C:N ratio, root lifespan, root cross-sectional area (CSA), stele CSA, proportion of stele in root CSA, mean xylem vessel CSA and the number of xylem vessels all increased with root order for the three shrubs, while specific root length and nitrogen concentration decreased with root order. The combined root biomass of the first two orders accounted for more than 63% of the first–fourth order root biomass for all the three shrubs. Proportion of stele to root CSA and number of xylem vessels of third-order root segments were significantly higher than that of the first two orders, and third-order roots showed secondary development with a continuous cork layer. All first-order and most second-order roots exhibited primary development, had an intact cortex, a lower proportion of stele to root CSA, and a smaller number of vessels. Our research suggests that the first two order roots of shrubs in sandy habitats are responsible mainly for absorption, and that they play a major role in root turnover and C and N flux in the soil organic matter pool due to their high proportion of biomass and N concentration, as well as their short lifespan.     

栓皮栎根系解剖结构、水力特性及碳、氮含量研究

为阐明栓皮栎根系随径级的变化规律,探究其细根的合理划分标准。以1年生栓皮栎幼苗为研究对象,将其根系分为1、1～2、2～3、3～4 mm四个径级,分别制作石蜡切片观察解剖结构,比较木质部水力特性,测定碳氮含量及其比值,并采用主成分法对根系进行分类。结果表明:(1)随着径级增加,栓皮栎根系周皮、韧皮部和形成层组织厚度增加而占径比降低,木质部直径及其占径比均增加。(2)直径2 mm以上的栓皮栎根系木质部平均最大和最小导管直径、根比导水率和栓塞脆弱性指数增加显著;而导管密度显著下降,导管面积与木质部面积之比变化不显著。(3)直径2 mm以上栓皮栎根系碳含量表现出显著增加,随着径级增加,根系氮含量下降、碳氮比升高。(4)主成分分析表明,13项根系结构和元素含量指标降维后,前2个主分量方差贡献率达62%,PCA双序轴显示栓皮栎根系可划分为2 mm以下的吸收根群和2 mm以上的运输根群。综上认为,以2 mm作为栓皮栎细根划分的标准兼顾了形态和功能的特点,更具有准确性。     

不同品种吊兰根初生木质部原型的观察与比较

以3个品种吊兰(金边吊兰、银心吊兰、银边吊兰)为材料,采用徒手切片的方法研究了吊兰根初生木质部原型与品种、生境及根直径的t关系。结果表明,不同品种的吊兰根初生木质部原型存在着差异;在水培条件下,吊兰根初生木质部原型与土培条件下的不同,水培条件下的根初生木质部束远少于土培条件;在水培条件下,吊兰根初生木质部原型与根的直径存在正相关关系,但是在土培条件下银心吊兰和银边吊兰根初生木质部原型则和根的直径没有关系。     

Vessel-diameter distribution in roots of grapevines (Vitis vinifera L. cv. Shiraz)

The distribution frequency patterns of diameter of xylem vessels and percentage of total predicted axial conductances were studied in 190-day and 212-day-old main roots of grapevine (Vitis vinifera L. cv. Shiraz) grown under well-watered and stressed conditions. The protoxylem were the first to mature and were responsible for most of the theoretical conductance in root segments between the tip and 2.5 cm from the tip. Some large xylem vessels retained cross walls and protoplasm up to 22.5 cm from the tip. Statistical tests using the Kolmogorov-Smirnov two sample test showed that the pattern of distribution frequency of xylem vessels classified in different diameter classes varied with distance from the root tip. The distribution frequency of xylem vessels was similar in both well-watered and stressed plants from the tip up to 15 cm from the tip. At distances further from the tip the distribution frequency of xylem vessels of well-watered plants was significantly different from that of stressed plants, with the former having more larger vessels than the latter. The pattern of vessel distribution frequency was different from that of percent total axial conductance (K_h) predicted with fewer large vessels carrying most of the axial flow.     

Anatomical root variations in response to water deficit: wild and domesticated common bean (Phaseolus vulgaris L)

Root anatomical responses to water deficit are diverse and regulation of water uptake strongly depends on plant anatomy. The ancestors of common bean (Phaseolus vulgaris L.) cultivars are the wild common beans. Because wild beans adapt and survive well in the natural environment, it is hypothesized that wild common bean roots are less affected than those of domesticated beans at low substrate water potential (ψW). A wild common bean accession from Chihuahua Mexico and cv. Bayomex were studied. Seedlings with a mean root length between 3 and 4 cm were maintained for 24 h in vermiculite at ψW of -0.03 (well hydrated), -0.65, -1.48 and -2.35 MPa (partially dry). Ten anatomical characteristics of differentiation and cell division in root regions were evaluated. Thickness of epidermis and protoderm diminished similarly in wild and domesticated beans growing at low substrate ψW (between -0.65 and -2.35 MPa). At the same time, parenchymatic cell area diminished by 71 % in the domesticated variety, but by only 32 % in the wild bean at -2.35 MPa. The number of cells in the cortex and the thickness of the xylem wall increased in both wild and domesticated beans at low substrate ψW; nevertheless, the effect was significantly lower in the wild bean. The number of xylem vessels increased in the cultivar (up to 40 %) while in the wild bean it decreased (up to 33 %). The diameter of xylem vessels and transverse root area diminished (15 and 57 %, respectively) in the cultivar, but in the wild common bean were not affected. Anatomical root characteristics and their modifications in both differentiation and cell division in root regions demonstrated that the wild bean reacted quite differently to substrate ψW than the domesticated common bean.     

Influence of xylem development on axial hydraulic conductance within Prunus root systems

The effect of secondary growth on the distribution of the axial hydraulic conductance within the Prunus root system was investigated. Secondary growth resulted in a large increase in both the number (from about 10 to several thousand) and diameter of xylem vessels (from a few micrometres to nearly 150 µm). For fine roots (<3 mm), an increase in root diameter was correlated with a slight increase in the number of xylem vessels and a large increase in their diameter. Conversely, for woody roots, an increase in root diameter was associated with a dramatic increase in the number of xylem vessels, but little or no change in vessel diameter. The theoretical axial conductivity (Kh, m⁴.s^-1.MPa^-1) of root segments was calculated with the Poiseuille-Hagen equation from measurements of vessel diameter. Kh measured using the tension-induced technique varies over several orders of magnitude (7.4᎒^-11 to 5.7᎒^-7 m⁴.s^-1.MPa^-1) and shows large discrepancies with theoretical calculated Kh. We concluded that root diameter is a pertinent and useful parameter to predict the axial conductance of a given root, provided the root type is known. Indeed, the relationship between measured Kh and root diameter varies according to the root type (fine or woody), due to differences in the xylem produced by secondary growth. Finally, we show how the combination of branching pattern and axial conductance may limit water flow through root systems. For Prunus, the main roots do not appear to limit water transfer; the axial conductance of the main axes is at least 10% higher than the sum of the axial conductance of the branches.     

毛乌素沙地降水格局变化对油蒿木质部解剖特征的影响

探究不同降水处理对荒漠植物木质部解剖特征的影响,可以为理解未来降水格局变化下荒漠植物适应性和预测荒漠植被演替趋势提供理论依据。以毛乌素油蒿灌丛植被为对象,通过野外人工控制降水的方法,模拟半干旱气候区降水格局变化趋势,设置3个降水量梯度（减水30%、自然降水、增水30%）以及2个降水间隔梯度（降水间隔5d、降水间隔15d）开展双因素完全随机试验,监测油蒿木质部各个解剖特征参数对不同降水处理的响应。结果表明：（1）随着降水量减少,油蒿的导管数量显著增多,导管密度、导管壁厚度显著增大（P<0.05）。降水间隔时间延长将显著增加油蒿的导管数量、导管密度和平均导管直径（P<0.05）。降水量与降水间隔期对油蒿木质部解剖学特征影响的交互效应不显著。（2）降水量减少和降水间隔时间延长弱化了油蒿潜在最大导水率对导管直径的响应敏感度。（3）在降水量减少和延长降水间隔时间的背景下,油蒿可以通过调整木质部导管参数兼顾水分运输的安全与效率。本研究表明,通过改变木质部解剖学特征参数来适应降水格局改变是油蒿的重要耐旱策略,未来气候变化的大背景下,荒漠植物的水力特征变化需要综合考量降水量和降水间隔的双重影响。