贵州小檗属植物(小檗科)叶脉序研究

采用制作叶脉标本和透明叶标本的方法,对贵州产28种2变种小檗属植物叶脉特征进行比较研究。结果表明:贵州小檗属植物的脉序类型有5种:半达缘羽状脉、花环状半达缘羽状脉、简单弓形羽状脉、花环状弓形羽状脉和混合型。叶脉分支一般有五级:1一级脉构架均为羽状脉,粗度有很粗、粗、中等粗细和纤细四种类型,分支方式包括单轴分支和合轴分支;2粗二级脉构架中有分支达缘或分支均不达缘,与中脉夹角变化各异,内二级脉存在或缺失,细二级脉半达缘、真曲行或简单弓形,间二级脉类型复杂多变但频度种间有差异;3三级脉贯串型、结网型或分支型;4四、五级脉网状或自由分支且常混合在一起。脉间区从发育差到良好,小脉从不分支到不均等分支等各种类型均有,叶缘末级脉缺失、不完整、钉状和环状。大部分种类叶缘具齿,每1cm齿数目和齿内腺点的特性等特征在不同种类间有区别,具有鉴定价值,但齿其它特征复杂多变或种间区别较小,同时齿内脉性状也不稳定。此外,齿的有无会对脉序类型产生影响。小檗属植物叶脉类型存在种间差异,具有重要的分类学价值,叶脉类型的变化和复杂程度显示了该属植物的进化特点;叶齿的有无和齿特征具有分类学和系统学意义。基于叶脉特征的研究结果并结合重要的外部形态学特征编制了贵州小檗属植物的分种检索表。研究结果可为小檗属植物分类寻找新的依据并探讨其系统学意义。     

Foliar architecture of vanilloid orchids: insights into the evolution of reticulate leaf venation in monocotyledons

Leaves of representative taxa within the vanilloid clade of Orchidaceae were cleared and their venation patterns studied. Within subtribe Pogoniinae, Isotria and Pogonia exhibit a prominent reticulate venation pattern, although only Pogonia ophioglossoides is characterized by free vein endings. Within subtribe Vanillinae, all species of Epistephium , as well as the New Caledonian endemics, Eriaxis rigida and Clematepistephium smilacifolium , have reticulate-veined leaves that are characterized by numerous free vein endings. Leaves of most species of Vanilla exhibit a parallel-veined pattern stereotypical of monocots, although branched secondaries with free endings were observed in V. africana. Most members of subtribe Galeolinae are 'saprophytes' with reduced bract-like leaves. Vascular bundles enter these leaf-homologues in a parallel manner, but quickly ram+ throughout the tissue in an irregular manner. Leaf venation is used to hypothesize patterns of generic relationships within the vanilloid clade. Molecular evidence for phylogenetic relationships among angiosperms indicates that reticulate leaf venation has arisen independently in several unrelated monocot families, including the vanilloid Orchidaceae, perhaps by a similar evolutionary scenario.     

Leaf architecture of South American Nothofagus (Nothofagaceae) using traditional and new methods in morphometrics

Leaf morphology has been the subject of several studies in NoNothofagur especially in the context of the taxonomy and evolutionary relationships of taxa within the genus, which are still controversial. The leaf architecture of 8 dombgi , N. betuloides and N. nitida , dominant trees of temperate forest in southern South America, is compared using venation patterns, landmarks, and entire outlines. In terms of venation patterns N. dombgi and N. betuloides were more similar to each other than to N. nitida. Similar results were found when differences in shape were analysed by discriminant analyses of shape coordinates (landmarks) and Fourier coefficients (outlines). For both analyses, the fwst discriminant function separated N. nitida from the other two species; these were also distinguished but showed greater overlap with each other. This study, in concert with information from allozyme data confirms the hypothesis of a more ancestral position for N. nitida with N. dombgi and N. betuloides being more recently derived. In addition to differences in shape, the size component of leaf morphology indicated that whereas N. betuloides had the smallest leaves, N. dombgi spanned the greatest range and has the biggest leaves. Given that the data shown here were obtained from seedlings grown under common-garden conditions, differences in both shape and size, seem to be important components of leaf morphology that may warrant consideration in characterizing these and other species of Nothofagus.     

中国木犀属植物叶脉形态及其分类学意义

观察了中国木犀属植物4组19种叶脉形态。主要分析木犀属植物叶片脉序走向,脉序为环结曲行或半直行羽状脉。二级脉急转曲行或半直行,叶脉分支一般为4级,少数5级。盲脉1～2次分支,少数3次或不分支。仅柊树叶缘末级脉汇合成边脉.部分叶缘具齿,叶缘齿性状不稳定,因其内主脉不同而在本属种间表现出一个连续的变异过程。圆锥花序组与李榄属和木犀榄属从叶片脉序特征方面表现出较近的亲缘关系。四个组的叶脉形态在演化上关系上与花粉形态表现相一致。编写了叶片脉序特征分种检索表。     

grasviq: an image analysis framework for automatically quantifying vein number and morphology in grass leaves

Beyond facilitating transport and providing mechanical support to the leaf, veins have important roles in the performance and productivity of plants and the ecosystem. In recent decades, computational image analysis has accelerated the extraction and quantification of vein traits, benefiting fields of research from agriculture to climatology. However, most of the existing leaf vein image analysis programs have been developed for the reticulate venation found in dicots. Despite the agroeconomic importance of cereal grass crops, like Oryza sativa (rice) and Zea mays (maize), a dedicated image analysis program for the parallel venation found in monocots has yet to be developed. To address the need for an image-based vein phenotyping tool for model and agronomic grass species, we developed the grass vein image quantification (grasviq ) framework. Designed specifically for parallel venation, this framework automatically segments and quantifies vein patterns from images of cleared leaf pieces using classical computer vision techniques. Using image data sets from maize inbred lines and auxin biosynthesis and transport mutants in maize, we demonstrate the utility of grasviq for quantifying important vein traits, including vein density, vein width and interveinal distance. Furthermore, we show that the framework can resolve quantitative differences and identify vein patterning defects, which is advantageous for genetic experiments and mutant screens. We report that grasviq can perform high-throughput vein quantification, with precision on a par with that of manual quantification. Therefore, we envision that grasviq will be adopted for vein phenomics in maize and other grass species.     

Quantitative analysis of venation patterns of Arabidopsis leaves by supervised image analysis

The study of transgenic Arabidopsis lines with altered vascular patterns has revealed key players in the venation process, but details of the vascularization process are still unclear, partly because most lines have only been assessed qualitatively. Therefore, quantitative analyses are required to identify subtle perturbations in the pattern and to test dynamic modeling hypotheses using biological measurements. We developed an online framework, designated Leaf Image Analysis Interface (LIMANI), in which venation patterns are automatically segmented and measured on dark-field images. Image segmentation may be manually corrected through use of an interactive interface, allowing supervision and rectification steps in the automated image analysis pipeline and ensuring high-fidelity analysis. This online approach is advantageous for the user in terms of installation, software updates, computer load and data storage. The framework was used to study vascular differentiation during leaf development and to analyze the venation pattern in transgenic lines with contrasting cellular and leaf size traits. The results show the evolution of vascular traits during leaf development, suggest a self-organizing mechanism for leaf venation patterning, and reveal a tight balance between the number of end-points and branching points within the leaf vascular network that does not depend on the leaf developmental stage and cellular content, but on the leaf position on the rosette. These findings indicate that development of LIMANI improves understanding of the interaction between vascular patterning and leaf growth.     

Studies on the leaf anatomy of Euphorbia: II. Venation patterns*

Leaf venation patterns of 150 species of Euphorbia are presented and their value as a diagnostic feature in the genus assessed. Based on the gross venation patterns, the species have been grouped into uni-, bi-, tri-veined and special categories. The majority of the species studied belonged to the tri-veined category, in which ornamentation of the veins and the course of traces in the lamina proved useful additional characters. Features such as the size of the areoles, the number of vein endings, and their further ramifications and composition in each areole varied in the same leaf or in different leaves of a given species. Furthermore, no direct correlation could be established between the areole size and the numbers of vein endings and tips per areole. Forty species possess a parenchymatous vein sheath. Globular chloroplasts showed up conspicuously in the sheath cells of a few species. Dilated tracheidal elements, localized on the venules or at the tips of vein endings, are characteristic of the xerophytic species. In some instances, correlation was apparent between plants grouped according to their venation patterns and their habit.     

Evolutionary relationships of wing venation and wing size and shape in Aphidiinae (Hymenoptera: Braconidae)

We explored evolutionary changes in wing venation and wing size and shape in Aphidiinae, one of the well-known groups of parasitic wasps from the family Braconidae. Forewings of 53 species from 12 genera were examined, for which a molecular phylogeny was constructed on the basis of the mitochondrial barcoding gene COI. By covering all types of wing venation within the subfamily Aphidiinae and by using landmark-based geometric morphometrics and phylogenetic comparative methods, we tested whether evolutionary changes in wing shape correlate to the changes in wing venation and if both changes relate to wing size. The relationship between wing morphology and host specificity has been also investigated. We found that six types of wing venation, with different degree of vein reduction, could be recognized. Wing venation type is largely genus specific, except in the case of maximal reduction of wing venation which could be found across examined Aphidiinae taxa. The reconstruction of evolutionary changes in wing venation indicates that evolutionary changes in wing shape are related to the changes in wing size, indicating that miniaturization play a role in evolution of wing morphology while host specialization does not affect the wing shape within the subfamily Aphidiinae.     

Cotyledon venation patterns in the Leguminosae: Mimosoideae

Cotyledon venation patterns are described for 131 species representing the four main tribes of the Mimosoideae. The range of variation in venation pattern falls within that described previously for the Caesalpinioideae and is consistent with the proposal that all patterns in the Leguminosae have been derived from a prototype with four vascular strands and a protoxylem trace in the petiole and seven primary veins in the lamina. Each tribe is characterized by a particular set of patterns, pattern frequencies and evolutionary trends. In the Mimoseae, correlations between venation pattern and cotyledon size and anatomy match those found in the Caesalpinioideae, but different correlations unique to these tribes occur in the Acacieae and Ingeae.     

叶脉网络功能性状及其生态学意义

叶脉网络结构是叶脉系统在叶片里的分布和排列样式。早期叶脉网络结构研究主要集中在其分类学意义上; 近年来叶脉网络功能性状及其在植物水分利用上的意义已成为植物生态学研究的热点。该文介绍了叶脉网络功能性状的指标体系(包括叶脉密度、叶脉直径、叶脉之间的距离、叶脉闭合度等), 综述了叶脉网络功能性状与叶脉系统功能(包括水分、养分和光合产物等物质运输、机械支撑和虫害防御等)的关系, 叶脉网络功能性状与叶片其他功能性状(包括比叶重、叶寿命、光合速率、叶片大小、气孔密度等)的协同变异和权衡关系, 以及叶脉网络功能性状随环境因子(包括水分、温度、光照等)的变化规律等方面的最新研究进展。此外, 叶脉网络功能性状的研究成果也被应用于古环境重建、城市交通规划、流域规划及全球变化研究中。由于叶脉网络功能性状是环境因子与系统发育共同作用的结果, 未来开展分子—叶片—植物—生态系统等多尺度的叶脉网络功能性状研究, 理清叶脉网络功能性状与气孔失水—茎干导水—根系吸水等植物水分利用的关系, 将为预测植物及生态系统对全球变化的响应提供新的启示。     

CLASSIFICATION OF THE ARCHITECTURE OF DICOTYLEDONOUS LEAVES

A classification of the architectural features of dicot leaves—i.e., the placement and form of those elements constituting the outward expression of leaf structure, including shape, marginal configuration, venation, and gland position—has been developed as the result of an extensive survey of both living and fossil leaves. This system partially incorporates modifications of two earlier classifications: that of Turrill for leaf shape and that of Von Ettingshausen for venation pattern. After categorization of such features as shape of the whole leaf and of the apex and base, leaves are separated into a number of classes depending on the course of their principal venation. Identification of order of venation, which is fundamental to the application of the classification, is determined by size of a vein at its point of origin and to a lesser extent by its behavior in relation to that of other orders. The classification concludes by describing features of the areoles, i.e., the smallest areas of leaf tissue surrounded by veins which form a contiguous field over most of the leaf. Because most taxa of dicots possess consistent patterns of leaf architecture, this rigorous method of describing the features of leaves is of immediate usefulness in both modern and fossil taxonomic studies. In addition, as a result of this method, it is anticipated that leaves will play an increasingly important part in phylogenetic and ecological studies.     

国产五味子科五种植物叶片脉序研究

首次报道了国产五味子科５种植物的叶脉特征,对科、属、种的特征作了描述,编排有分种检索表．通过与八角科叶脉的比较,支持建立五味子科与八角科的观点,认为五味子属的系统位置在南五味子属之后,并讨论了八角目的演化趋势     

Optimization of leaf morphology in relation to leaf water status: A theory

The leaf economic traits such as leaf area, maximum carbon assimilation rate, and venation are all correlated and related to water availability. Furthermore, leaves are often broad and large in humid areas and narrower in arid/semiarid and hot and cold areas. We use optimization theory to explain these patterns. We have created a constrained optimization leaf model linking leaf shape to vein structure that is integrated into coupled transpiration and carbon assimilation processes. The model maximizes net leaf carbon gain (NPP_leaf) over the loss of xylem water potential. Modeled relations between leaf traits are consistent with empirically observed patterns. As the results of the leaf shape–venation relation, our model further predicts that a broadleaf has overall higher NPP_leaf compared to a narrowleaf. In addition, a broadleaf has a lower stomatal resistance compared to a narrowleaf under the same level of constraint. With the same leaf area, a broadleaf will have, on average, larger conduits and lower total leaf xylem resistance and thus be more efficient in water transportation but less resistant to cavitation. By linking venation structure to leaf shape and using water potential as the constraint, our model provides a physical explanation for the general pattern of the covariance of leaf traits through the safety–efficiency trade‐off of leaf hydraulic design.     

Cotyledon venation patterns in the Leguminosae: Gaesalpinioideae

Cotyledon venation patterns are described for 93 species representing all tribes of the Caesalpinioideae. Patterns are grouped into a series of levels of complexity according to the number of primary veins, nine, seven, six, five, three or one, but five- and three-vein patterns predominate. The number of petiolar vascular strands varies from one to eight but most species have two or four strands. It is proposed that all the patterns have been derived from one in which four strands and a protoxylem trace in the petiole branch and anastomose to form seven primary veins in the lamina. Venation patterns show correlations with cotyledon anatomy, size and shape and with taxonomic grouping at tribal, infratribal and generic levels. Each tribe is characterized by a particular set of related patterns, pattern frequencies and evolutionary trends.     

Menispermaceae from the Cerrejon Formation, middle to late Paleocene, Colombia

The origin and processes creating the high diversity of plant species in neotropical rain forests and their floristic composition and multistratitified forest structure are still uncertain. Here, we studied one of the most common leaf morphotypes of the Cerrejón flora (middle-late Paleocene, ca. 60-58 Ma), Guajira, Colombia, that contains one of the oldest records of neotropical rain forest floras. Fifty-seven leaf specimens were carefully examined with a focus on general morphology, venation patterns, and cuticular characteristics. The analysis allowed us to recognize four new species that were assigned to the fossil-leaf genus Menispermites on the basis of an ovate leaf shape with cordate to truncate bases, actinodromous primary venation, brochidodromous secondary venation, percurrent tertiary venation, regular polygonal reticulate fourth and fifth venation, well-developed polygonal?areoles, entire margin, and the presence of a fimbrial vein. This set of characters suggests a possible affinity with the pantropical angiosperm family Menispermaceae. The predominantly climbing habit of this family suggests that the Cerrejón Paleocene tropical rain forest was already multistratified. These findings represent the earliest record for the family in northern South America.     

Leaf architectural studies in the brassicaceae

The leaf architecture has been studied in 19 genera and 35 species of the Brassicaceae. The major venation pattern is pinnate craspedodromous with the exception ofAlyssum maritimum, Iberis amara, I. umbellata andMalcolmia maritima where it is pinnate-festooned brochidodromous. The number of secondary veins and their angle of divergence vary from species to species and even within the same species. Marginal ultimate venation is mostly looped occasionally incomplete. The areole size and shape is variable. The veinlets may be simple or once or twice dichotomously divided. The simple veinlets may be curved or hooked. The tracheids are either uni-, bi-, tri- or multiseriate and extraordinarily variable in size and shape. Isolated vein endings, isolated free vein endings, isolated tracheids and extension cells are observed. Myrosin cells have been observed inEruca vesicaria ssp.sativa andCochlearia cochlearioides.     

Equivalent genetic regulatory networks in different contexts recover contrasting spatial cell patterns that resemble those in Arabidopsis root and leaf epidermis: a dynamic model

In Arabidopsis thaliana, leaf and root epidermis hairs exhibit contrasting spatial arrangements even though the genetic networks regulating their respective cell-fate determination have very similar structures and components. We integrated available experimental data for leaf and root hair patterning in dynamic network models which may be reduced to activator-inhibitor models. This integration yielded expected results for these kinds of dynamic models, including striped and dotted cell patterns which are characteristic of root and leaf epidermis, respectively. However, these formal tools have led us to novel insights on current data and to put forward precise hypotheses which can be addressed experimentally. In particular, despite subtle differences in the root and leaf networks, these have equivalent dynamical behaviors. Our simulations also suggest that only when a biasing signal positively affects an activator in the network, the system recovers striped cellular patterns similar to those of root epidermis. We also postulate that cell shape may affect pattern stability in the root. Our results thus support the idea that in this and other cases, contrasting spatial cell patterns and other evolutionary morphogenetic novelties originate from conserved genetic network modules subject to divergent contextual traits.