Leaf anatomical studies of Chamaecrista subsect. Baseophyllum (Leguminosae, Caesalpinioideae): new evidence for the up-ranking of the varieties to the species level

This study aims to determine whether morphoanatomical characters of the leaves of the species of Chamaecrista sect. Absus subsection Baseophyllum could be used to support an up-ranking of C. cytisoides varieties to the species level as previously defined by molecular studies. The significance of anatomical adaptive strategies to arid environments is also discussed. Standard light microscopy techniques and histochemical tests were used for both morphoanatomical and histochemical characterization of the leaves. All the species studied share a single-layered epidermis, actinodromous–camptodromous–brochidodromous type of venation, vascular bundles surrounded by layers of fibers bounded externally by a sheath of cells containing solitary crystals, enlarged tracheids at the vein endings, vascular petiole/rachis tissue with a parenchymatous pith, accessory vascular bundles, mucilage idioblasts and hypodermis in the mesophyll, colleters, and non-secretory trichomes. The position and type of stomata, type of mesophyll, number of palisade and spongy parenchyma layers, position of mucilage idioblasts in the mesophyll, and the number of accessory vascular bundles of petiole/rachis provided useful characters for discriminating the eight species of the subsect. Baseophyllum. Histochemical tests reveal the presence of total polysaccharides, pectins, mucilage and phenolic compounds in the idioblasts. Other xeromorphic characters such as thickened outer periclinal cell walls, compact mesophyll, mucilage idioblasts and hypodermis in the mesophyll may help enable the studied species to survive in exposed sunny areas.     

A novel insight into the structure of amphivasal secondary bundles on the example of Dracaena draco L. stem

Key message

Pattern of tracheids found along the bundles extends understanding of their cross - sectional anatomy and sheds a new light on the issue of radial transport in monocotyledons with secondary growth.

Abstract

Secondary growth of Dracaena draco L. stem is connected with the formation of amphivasal vascular bundles in which a centrally located phloem is surrounded by a ring of xylem cells (tracheids). However, as visible in a single transverse section, there is a tendency towards variation among the secondary bundles from such with a xylem ring to ones in which the tracheids do not completely surround the phloem, i.e., are separated by vascular parenchyma cells. We aimed to elucidate the cross-sectional anatomy of amphivasal secondary bundles using the method of serial sectioning (with sections 3 μm thick), which allowed us to follow very precisely the bundle structure along its length. The analysis revealed that the xylem arrangement in these bundles depends on the position of a section in the bundle path. Each amphivasal bundle is composed of sectors where tracheids form a ring, as well as of such where tracheids are separated by vascular parenchyma cells. We hypothesize that this structure of amphivasal vascular bundles facilitates radial transport of assimilates to the sink tissues. The result of the anatomical analysis is discussed in a physiological context.     

The Vascular System in the Rachis of a Wheat Ear

The vascular system in the rachis of ears of wheat (Triticumaestivum L. cvs Gamenya, Olympic and Bungulla) was examinedon material grown in the field and in a growth cabinet. In theinternodes, central and peripheral bundles were observed andtheir mean number and size were determined. A significant 1:1 relationship between the number of spikelets on the ear andthe number of central bundles at the base of the rachis wasestablished. The number of both central and peripheral bundlesdeclined acropetally along thé length of the rachis.The decline in peripheral bundles occurred mainly between internodes1 and 6, numbered from the base. The decline in central bundlesoccurred at a rate of less than one bundle per internode betweeninternodes 1 and 4, though in some ears, there was no decline;in larger ears, central bundles declined at a rate of one totwo bundles per internode between internodes 5 and 11. Aboveinternode 11, the rate of decline varied with ear size. Threecentral bundles consistently reached the terminal spikelet.The number and cross-sectional surface area of xylem vesselsand sieve tubes and the total vascular size also declined acropetallyalong the rachis. The decline in total vascular size was dueto (a) some bundles branching and to reductions in size, (b)the diversion or dropping of bundles into spikelets, or (c)a combination of (a) and (b). These observations are discussedin relation to the distribution of grain number and weight onthe ear. Triticum aestivum L., wheat, rachis, spikelets, vascular anatomy, xylem, sieve tubes     

The development of the tuber in seedlings of five species of Dioscorea from Nigeria

Tubers in all five species develop from the hypocotyl region of the seedlingS. A perivascular cambium arises cutting off mainly starch-storing parenchyma and collateral vascular bundles to the inside. A phellogen gives rise to cork on the outside. Between the two cambial layers there may or may not be layers of parenchyma, not storing starch but containing raphides. The vascular bundles consist of xylem with vessels, scalariform tracheids and parenchyma; and phloem, with sieve tubes and parenchyma.     

山茱萸果皮的解剖学研究

本文报导了山茱萸果皮的解剖学研究结果.外果皮由一层表皮细胞构成.中果皮外方为3-4(5)层厚角组织细胞,这些细胞通常含有单宁;其内方包含薄壁细胞、单宁细胞和8束维管束.单宁细胞成团或零星分布于薄璧细胞中,前者的体积明显大于后者.单宁细胞的单宁与多糖结合在一起.维管束含有环纹、螺纹、梯纹、网纹及孔纹管胞,还有少数散生的纤维.内果皮高度木质化,主要由多种形状的石细胞组成,其间分布了肉眼可见、排列成环状的异细胞,偶见少数生活石细胞及薄壁细胞.内果皮有3束维管束.     

用RFLP标记剖析水稻穗颈维管束及穗部性状的遗传基础

采用籼、粳亚种间杂种F1(圭630×02428)花药培养获得的DH群体,对水稻穗颈大、小维管束数和倒数第2节间大、小维管束数等4个维管束性状,以及一、二次枝梗数,每穗颖花数3个穗部性状进行QTL分析,共检测到16个QTLs,其中有7个QTLs的加性效应较大,单个QTL的贡献率在20%以上。发现有4个QTLs成簇分布于第1染色体从RZ776到C11的大约35cM的区段上,来源于亲本"圭630"的这一染色体区段对穗颈大维管束、第2节间大维管束、第2节间小维管束和二次枝梗数4个性状的表达均具有增效作用。还讨论了利用分子标记辅助选择聚合增效QTLs、实现穗颈维管束性状遗传改良的策略。     

<Emphasis Type="Italic">Istchenkophyton filiciforme</Emphasis> gen. et sp. nov., a new small vascular plant with thick cuticle from the Devonian of Voronezh Region (European Russia)

Remains of a new small vascular plant, Istchenkophyton filiciforme gen. et sp. nov., are described from the Upper Givetian strata of Pavlovsk vicinity (Voronezh Region). The plant is characterized by a very thick cuticle (up to 300 μm), complex branching pattern, similar to that of a frond rachis, anomocytic stomata, and a well-developed vascular bundle with a central elongated in transversal section protoxylem strand and massive metaxylem composed chiefly of scalariform bordered-pitted tracheids. A reconstruction of the new plant is proposed; its ecology and systematic position are considered. In the light of new data relationships of problematic Devonian plants with thick cuticle are discussed.     

Further Observations on Zosterophllum yunnanicum Hsü

Zosterophyllum yunnanicum, an important and widely distributedspecies in the Lower Devonian of southern China, was first described by Hsü in 1966.Later then, Li and Cai (1977), Cai and Schweitzer (1983) described the details of itsmorpholegy, and compered it with other members of the genus Zosterophyllum. In thispaper, the materials of its tracheids, epidermal ceils, stomata and its spores have beenstudied. The tracheids of Z. Yunnanicum are annular, and 9–30 gm across. Epidermal cellsof the axes are elongate, polygonaI, ranging from 70–280 μm by 12–60 μm. The stomata are mainly fusiform, 65–80 μm in length and 40–70 μm in width, probably consisting of a pair of guard-cells enclosing a pore, 8–20μm long and about 1.5μm wide. The density of stomata evidently varied in different parts of the plant. The portion of the sporangium near the rim is composed of rectangle and elongate cells. Theremainder wall of the valve consists of elongate cells, folding often. Spores from the sporangia are 20–55 gm (average 37.1μm) in diameter, smooth with thickened in area of trilete mark, which are 1/4–2/3 of the radius of spore. Some spores look similar to the dispersed spore Retusotriles (Naum.) Streel 1964. Apparently this Plant is homosporous.     

与水稻籼粳分化有关的穗颈维管束性状基因的分子标记定位

水稻穗颈维管束数及其与穗一次枝梗数之比（V／R）是与籼粳分化有关的重要性状,采用籼粳交（圭630／02428）杂种F1花药培养获得的DH群体,对水稻穗颈维管束数,穗一次枝梗数及V／R比进行了QTL分析,检测到3个控制穗颈维管束数的QTL;其中,效应最大的qVB-8的贡献率为31．1％,加性效应值为1．96％,增效等位基因来自灿稻亲本圭630,2个控制一次枝梗数的QTL效应较小,但分别与控制穗颈维管束数的2个QTL同位,检测到影响V／R比的3个QTL,其中,效应最大的qV/R-1的贡献率为25．3％,被定位于第1染色体上,与落粒性基因sh-2紧密连锁（亦或为一因多效）。此外,还检测到4对和2对分别控制穗颈维管束数和V／R比的互作QTL。结果分析表明,水稻穗颈维管束数与穗一次枝梗数受不同的多基因系统控制,但这2个多基因系统的某些位点在基因组中具有同位性;在第1染色体上,控制V／R比,且效应最大的qV/R-1所在的染色体区段在水稻籼粳分化过程中可能具有重要作用。     

薯蓣属根状茎的组织结构和萆薢类药材鉴别

应用显微镜观察了中国薯蓣属根状茎组17种1亚种1变种根状茎组织结构。结果显示,(1)根状茎均由周皮、内外侧基本组织和散生维管束组成;(2)木栓层外方常见被挤压或残留的基本组织薄壁细胞,并有木化厚壁细胞及石细胞;外侧基本组织含有散生或稀疏排列成环的粘液细胞(含草酸钙针晶束);内侧基本组织占广大部位,薄壁细胞愈近中央部位的愈大,维管束绝大部分外韧型,无形成层;(3)木质部有大型管胞或导管,管壁孔纹或网纹增厚,大形筛管易见,导管多短节状,显示了演化上的原始性;淀粉粒形态结构多样。结果表明,薯蓣属根状茎组织结构特点可作为分类依据,并显示了该组为一个自然类群。其中,药材粉萆薢(粉背薯蓣、叉蕊薯蓣)、绵萆薢(绵萆薢、福州薯蓣)的原植物根茎组织结构具有明显的鉴别意义。     

云南元江普通野生稻穗颈维管束和穗部性状的QTL分析

以云南元江普通野生稻为供体亲本,籼稻品种特青为轮回亲本构建高代回交群体,用SSR标记构建连锁图谱,在第1、2、3、4、7和10染色体上定位到7个控制穗颈大维管束数的QTL,在第1、2、3、4和8染色体上定位到5个控制穗颈小维管束数的QTL,在第11和12以外的10条染色体上,共定位到15个控制穗一、二次枝梗数和穗颖花数QTL。来自野生稻的等位基因大多表现负效,能显著减少群体的穗颈维管束数、枝梗数和颖花数,说明从野生稻演化成栽培稻的过程中,可能淘汰了一些对产量不利的QTL,保留了有利的QTL。相当一部分控制穗颈维管束数、枝梗数及颖花数的QTL在染色体上成簇分布或紧密连锁,且加性效应的方向一致,从理论上解释了这些性状表型显著相关的遗传基础,同时也说明在人工选择或自然选择下,这些性状可能存在平行进化或协同进化的关系。     

XYLEM ANATOMY,WATER FLOW,AND HYDRAULIC CONDUCTANCE IN THE FERN CYRTOMIUM FALCATUM

Xylem anatomy and water relations were studied in holly fern (Cyrtomium falcatum, Aspidiaceae) to determine the details of the pathway for water flow through an entire plant and the influence of tracheid number and lumen diameter on water flow. Each leaf has two adaxial traces and an abaxial trace, which are supplied by diarch adventitious roots attached to the dictyostele of the rhizome near the leaf base. Anatomical observations and dye experiments showed that each adaxial bundle vascularizes the approximately seven pinnae on its side of a leaf. An abaxial bundle is intermittently connected to an adaxial bundle as well as other abaxial bundles, forming a minor vascular pathway between the bundles of the leaf axis. Changes in both number and diameter of tracheids result in an acropetal decrease in hydraulic conductance per unit length along the rachis, although tracheid number locally increases when the trace for a pinna is produced in an adaxial bundle. Water flow was determined from the transpiration distal to the point in question or by forcing a solution through an axis with applied pressure. The water potential gradient along the plant axis was quite constant, indicating that hydraulic conductance per unit length varied with leaf area to be supplied. About 40% of the overall water potential drop occurred from the rachis into the pinnae, which reflected factors controlling water potential gradients in the lamina and not a very low conductance in the petiolule xylem. Hydraulic conductances calculated using the Hagen-Poiseuille equation and tracheid diameters were generally double those of measured conductances. Since the values tended to vary by a constant factor, tracheid number and diameter may largely control water flow in the xylem.     

STRUCTURALLY PRESERVED FOSSIL PLANTS FROM ANTARCTICA. I. ANTARCTICYCAS,GEN. NOV., A TRIASSIC CYCAD STEM FROM THE BEARDMORE GLACIER AREA

Silicified stems with typical cycadalean anatomy are described from specimens collected from the Fremouw Formation (Triassic) in the Transantarctic Mountains of Antarctica. Axes are slender with a large parenchymatous pith and cortex separated by a narrow ring of vascular tissue. Mucilage canals are present in both pith and cortex. Vascular tissue consists of endarch primary xylem, a narrow band of secondary xylem tracheids, cambial zone, and region of secondary phloem. Vascular bundles contain uni- to triseriate rays with larger rays up to 2 mm wide separating the individual bundles. Pitting on primary xylem elements ranges from helical to scalariform; secondary xylem tracheids exhibit alternate circular bordered pits. Traces, often accompanied by a mucilage canal, extend out through the large rays into the cortex where some assume a girdling configuration. A zone of periderm is present at the periphery of the stem. Large and small roots are attached to the stem and are conspicuous in the surrounding matrix. The anatomy of the Antarctic cycad is compared with that of other fossil and extant cycadalean stems.     

Comparative leaf' anatomical studies of some Mallotus Lour. (Euphorbiaceae) species

A comparative study was undertaken on the leaves and petioles of 16 species of Mallotus in order to investigate anatomical variations of potential in species identification. There is a range of characters which varies between species. These include the outline of the midrib and petiole in transverse sections, the shape of the vascular tissue in midribs, the presence of central bundles in the petiole, the presence of terminal sclereids, enlarged tracheids, presence or absence of non-glandular trichomes, and parenchymatous sheaths in vascular bundles. A combination of these characters may be used to identify species. Anatomical data support the placing of only a few species into the respective sections.     

Development of the Vascular System in the Ear of Barley

In the mature rachis internodes of a two-row barley ear therewere two large lateral vascular bundles and a number of smallermedian and outer lateral vascular bundles. These bundles rannearly the full length of the rachis with no cross connectionsbetween them. The lateral and the outer lateral bundles branchedat every node while the median bundles branched at every othernode. The vascular bundles to each spikelet passed through acomplex region in which transfer cells occurred. Development of the vascular system of the young main shoot earstarted at the triple mound stage when the procambium of lateralbundles was initiated. Initiation of the median bundles andthe outer lateral bundles followed in sequence with some differentiationof protophloem and protoxylem. At awn initial stage of the earthe vascular connections to the spikelets were established withdifferentiation of the almost complete procambium proceedingthroughout the ear elongation phase. The progress of vascularisation in the young ear is discussedwith reference to spikelet initiation, ear relative growth rateand death of terminal spikelets. It is proposed that the changesin the relative growth rate of the ear and death of the terminalspikelets may be related to vascular differentiation     

The ultrastructural organization of the basement membrane of Bowman's capsule in the rat renal corpuscle

Summary The basement membrane of Bowman's capsule (BCBM) of the rat was studied by means of a modified tissue-preservation technique for transmission electron microscopy, which avoids the usual thorough fixation in OsO₄ and applies tannic acid and uranyl acetate for staining (Sakai et al. 1986). At most sites the BCBM is multilayered, consisting of one to seven dense layers separated by electron-lucent layers. The latter, which can be termed laminae rarae, contain fine filaments which connect the dense layers to each other and the innermost dense layer to the basal cell membrane of the parietal epithelium. The laminae densae are basically composed of fine filaments arranged in an anastomosing pattern. Individual filaments ranging from 5 to 15 nm in diameter, combine to form filament bundles up to 100 nm in thickness and 1 to 2 m in length. Within a dense layer, filaments and filamentous bundles are oriented mainly in the same direction. Often the inner dense layers do not form a continuous sheet, and the filamentous bundles are arranged in anastomosing or spiral patterns to form a ribbon-like structure that we call a microligament. These microligaments are often embedded in basal furrows of the parietal epithelium and are best developed around the vascular pole. Intracellular actin bundles of the parietal cells are regularly associated with these extracellular ribbon-like structures of the basement membrane. In conclusion, the BCBM has an unusual structure: the laminae densae are characterized by their filamentous nature and are arranged in different patterns, i.e. as a multilayered mat and as microligaments.Fellow of the Deutscher Akademischer Austauschdienst     

Surface structure and anatomical aspects of Chinese brake fern (Pteris vittata; Pteridaceae)

The objective of this study was to describe a wide spectrum of surface structural and anatomical details of the Chinese brake fern (Pteris vittata) using scanning electron microscopy (SEM). SEM revealed that the epidermal cells of the pinnae were elongated with raised periclinal and sinuous anticlinal walls. The pinnae were hypostomatous with randomly scattered anomocytic stomatal complexes positioned at the same level as the epidermis. Stomates were large and elliptical (27.4 μm × 10.2 μm). Cross sections from the central regions of the rachis and the stipe revealed V- and U-shaped vascular bundles, respectively. In each vascular bundle, the xylem strands were sea-horse shaped (hippocampus). In contrast, the pinnae possessed a triangular vascular bundle with uniform mesophyll organization comprising of homogenous lobed parenchyma cells. The indumentum consisted of trichomes and scales, which formed various types of vestiture. Trichomes were borne only on the pinnae and scales on the rachis and stipe. The roots developed a dense network of long root hairs averaging 244 μm long, and the xylem consisted of tracheids with scalariform pitting. Sori were submarginal; continuous along both margins of the pinna and were covered with a false indusium. The sporangia were oblong with a short thick stalk and the annulus was positioned vertically resulting in transverse dehiscence of the sporangium. The paraphyses were uniseriate, unbranched, septate and found to be intermixed with the sporangia. The exine of the globose spores was adorned with thick reticulum in which the areoles contained round tubercles. This study describes surface features in detail, which is essential to studies examining the issue of whether morphological characteristics are related to arsenic hyperaccumulation inP. vittata.     

New species of the isolated Psaroniaceous rachis from the Early Permian in China

A new kind of marattialean raches are reported from the coal balls in Coal Seam No.7 in the upper part of the Taiyuan Formation （early Early Permian） from Taiyuan, Shanxi, China and are assigned to the genus Stipitopteris Grand＇Eury （Psaroniaceae）. The present specimens are different from all six reported species of the genus, and are therefore proposed as a new species： Stipitopteris shanxiensis. The raches of the new species are generally dorsi-ventrally flattened. The main raches usually exhibit scales of different forms on their surface. Beneath the epidermis is a zone of parenchymatous cells, some of which contain tannin-like contents. Inside this is a zone of small sclerenchymatous cells. Inward are the ground tissue and vascular bundles. The vascular bundles are continuous and are in two circles： the outer circle assumes a transversely elliptical shape with the gap and pinna trace, and the inner circle assumes a shallow C.shape with inrolled ends. The ground tissue located at the inner side of the vascular bundle is composed of thicker-walled parenchymatous cells. The cells of the ground tissue are vertically elongated in longitudinal sections. Subordered raches are smaller and have simpler structures than the main raches. The parenchyma zone beneath the epidermis is thinner, usually one to two cells wide and the sclerenchyma zone is usually absent. The scales are poorly developed and there is only one C-shaped vascular bundle. The new species is comparable to the crosiers of Psaroniaceae of the Euramerican Flora in some aspects, for example, it has a dorsi-ventrally flattened rachis and scales on the surface of the rachis. However, the other features and the preservative conditions of the present specimens indicate that they are not crosiers, but fully developed or mature raches. The new species is the first well-studied anatomically-preserved rachis of Psaroniaceae from the Cathaysian Flora and bears significance not only in understanding the anatomy and taxonomy of Psaroniaceae in the Cathaysian Flora, but also in the relationship between the Euramerican Flora and the Cathaysian Flora.     

Unusual metaxylem tracheids in petioles of Amorphophallus (Araceae) giant leaves

BACKGROUND AND AIMS: Petioles of huge solitary leaves of mature plants of Amorphophallus resemble tree trunks supporting an umbrella-like crown. Since they may be 4 m tall, adaptations to water transport in the petioles are as important as adaptations to mechanical support of lamina. The petiole is a cylindrical shell composed of compact unlignified tissue with a honeycomb aerenchymatous core. In both parts numerous vascular bundles occur, which are unique because of the scarcity of lignified elements. In the xylemic part of each bundle there is a characteristic canal with unlignified walls. The xylem pecularities are described and interpreted. MATERIAL: Vascular bundles in mature petioles of Amorphophallus titanum and A. gigas plants were studied using light and scanning electron microscopy. KEY RESULTS: The xylemic canal represents a file of huge metaxylem tracheids (diameter 55-200 microm, length >30 mm) with unlignified lateral walls surrounded by turgid parenchyma cells. Only their end walls, orientated steeply, have lignified secondary thickenings. The file is accompanied by a strand of narrow tracheids with lignified bar-type secondary walls, which come into direct contact with the wide tracheid in many places along its length. CONCLUSIONS: The metaxylem tracheids in A. petioles are probably the longest and widest tracheids known. Only their end walls have lignified secondary thickenings. Tracheids are long due to enormous intercalary elongation and wide due to a transverse growth mechanism similar to that underlying formation of aerenchyma cavities. The lack of lignin in lateral walls shifts the function of 'pipe walls' to the turgid parenchyma paving the tracheid. The analogy to carinal canals of Equisetum, as well as other protoxylem lacunas is discussed. The stiff partitions between the long and wide tracheids are interpreted as structures similar to the end walls in vessels.     

PHLOEM STRUCTURE IN THE CARBONIFEROUS FERN PSARONIUS (MARATTIALES)

Phloem anatomy in stems of Psaronius is described from coal ball specimens collected at the Berryville, IL and Lewis Creek, KY localities. Phloem completely surrounds the C-shaped xylem segments, but is more extensively developed on the abaxial side of the trace. The phloem zone consists of a central band of large diameter (approximately 90–120 μm) sieve elements surrounded by a mixed zone of smaller sieve elements and phloem parenchyma. Phloem is separated from the xylem by a parenchymatous xylem sheath. On the abaxial side of the trace, a discontinuous arc of very small diameter cells (7.8 μm) is present between the xylem sheath and the metaxylem. These cells corrrespond in position and size to protophloem cells in living marattialeans. Metaphloem sieve elements exhibit discrete, circular-oval sieve areas on their side and end walls, some of which show evidence of sieve pores. Phloem structure in Psaronius is compared with that known for living members of the Marattiales.