Specific epithets of the flowering plants of central French Guiana

The epithets of the flowering plants of central French Guiana are classified into derivation categories. Specific epithets of the flowering plants of central French Guiana refer mostly to shapes (274 species), persons (252), places (212), appearance (146), and size (140). These categories account for 55% of names given to the plants of this flora. The most prolific publishers of names for the flora of central French Guiana are Aublet and Linnaeus, who were respectively the authors of 177 and 110 of the names of species (15% of the total) found in the flora of central French Guiana. Although many of the species names, such as those relating to place and person, are easy to categorize, many others are open to different interpretations. Specific epithets with different orthographies derived from Guiana or Guyana are discussed. In addition, problems in the use of diacritical marks and inconsistencies with spacing between the abbreviations of given names and surnames of authors of plant names are noted.     

New perspectives on the mechanisms of chromosome evolution in parasitic flowering plants

In an attempt to find any association between chromosomal characters and parasitism, a cytological study of parasitic flowering plants in Israel has been carried out. While no such association was found, evidence for three levels of chromosome evolution could be discerned: intra-chromosomal modifications, polyploidy per se , and genome restructuring in polyploids. Our conclusions may serve as a paradigm of the multiple pathways of chromosomal evolution in plants in general. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 138 , 117–122.     

An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV

Advances in recent years have revolutionized our understanding of both the context and occurrence of polyploidy in plants. Molecular phylogenetics has vastly improved our understanding of plant relationships, enabling us to better understand trait and character evolution, including chromosome number changes. This, in turn, has allowed us to appreciate better the frequent occurrence and extent of polyploidy throughout the history of angiosperms, despite the occurrence of low chromosome numbers in some groups, such as in Arabidopsis (A. thaliana was the first plant genome to be sequenced and assembled). In tandem with an enhanced appreciation of phylogenetic relationships, the accumulation of genomic data has led to the conclusion that all angiosperms are palaeopolyploids, together with better estimates of the frequency and type of polyploidy in different angiosperm lineages. The focus therefore becomes when a lineage last underwent polyploidization, rather than simply whether a plant is ‘diploid’ or ‘polyploid’. This legacy of past polyploidization in plants is masked by large‐scale genome reorganization involving repetitive DNA loss, chromosome rearrangements (including fusions and fissions) and complex patterns of gene loss, a set of processes that are collectively termed ‘diploidization’. We argue here that it is the diploidization process that is responsible for the ‘lag phase’ between polyploidization events and lineage diversification. If so, diploidization is important in determining chromosome structure and gene content, and has therefore made a significant contribution to the evolutionary success of flowering plants. © 2015 The Authors. Botanical Journal of the Linnean Society published by John Wiley & Sons Ltd on behalf of Linnean Society of London, 2016, 180 , 1–5.     

Plant DNA barcode library for native flowering plants in the arid region of northwestern China

DNA barcoding is a well-established tool for rapid species identification and biodiversity monitoring. A reliable and traceable DNA barcode reference library with extensive coverage is necessary but unavailable for many geographical regions. The arid region in northwestern China, a vast area of about 2.5 million km², is ecologically fragile and often overlooked in biodiversity studies. In particular, DNA barcode data from the arid region in China are lacking. We develop and evaluate the efficacy of an extensive DNA barcode library for native flowering plants in the arid region of northwestern China. Plant specimens were collected, identified and vouchered for this purpose. The database utilized four DNA barcode markers, namely rbcL, matK, ITS and ITS2, for 1816 accessions (representing 890 species from 385 genera and 72 families), and consisted of 5196 barcode sequences. Individual barcodes varied in resolution rates: species- and genus-level rates for rbcL, matK, ITS and ITS2 were 79.9%–51.1%/76.1%, 79.9%–67.2%/88.9%, 85.0%–72.0%/88.2% and 81.0%–67.4%/84.9%, respectively. The three-barcode combination of rbcL + matK + ITS (RMI) revealed a higher species- and genus-level resolution (75.5%/92.1%, respectively). A total of 110 plastomes were newly generated as super-barcodes to increase species resolution for seven species-rich genera, namely Astragalus, Caragana, Lactuca, Lappula, Lepidium, Silene and Zygophyllum. Plastomes revealed higher species resolution compared to standard DNA barcodes and their combination. We suggest future databases include super-barcodes, especially for species-rich and complex genera. The plant DNA barcode library in the current study provides a valuable resource for future biological investigations in the arid regions of China.     

逆境诱导植物开花的研究进展

植物在长期的进化过程中形成了对环境改变的适应机制。在逆境条件下,例如干旱、高盐、低温、强光、弱光、紫外线等,植物会提前开花结实以尽早完成其生命周期,这种生物学现象被称为"逆境诱导的开花"。植物的这种避逆应激反应不但在进化上具有非常重要的生物学意义,而且对农业生产也具有重要的指导意义。逆境诱导植物开花与光周期、春化、环境温度、自主途径、赤霉素和年龄等开花途径的分子调控机制不同,有其自身的特点。文中对逆境诱导植物开花的研究历史、代谢调控以及分子机制等进行了阐述,并展望了未来的研究方向。     

31种木本植物开花物候与系统发育的关系

植物物候通常被认为是由环境因素,如降水、温度和日照长度所决定,然而环境因素是否是物候唯一的决定因素仍然存在很大争议。谱系结构表征了植物在进化上的顺序,该发育时序是否对物候产生影响,当前仍然未知。在调查2016年春季新疆乌鲁木齐市最常见的31种木本植物的初始开花时间、败花时间和开花持续时间的基础上,通过分析植物开花物候的分布特征、开花物候在乔灌木间的差别、以及植物谱系距离与开花物候距离间的关系,试图揭示植物的开花物候和物种谱系(进化)顺序间的关系。结果表明:(1)新疆乌鲁木齐市31种木本植物的初始开花时间为4月18日±9d、败花时间为5月5日±12d、开花持续时间为(16±8)d;(2)乔木的初始开花时间和败花时间的标准差分别均低于灌木,乔木开花物候相对灌木更稳定;(3)乔木的初始开花和败花时间均显著早于灌木(P0.05),但开花持续时间在两者间未有显著性差异(P0.05);(3)31种木本植物间的初始开花时间距离、败花时间距离和开花持续时间距离均与物种谱系距离存在显著线性回归关系(P0.05)。综上可知:乔灌木在垂直空间上的分化使得木本植物的开花物候在植物生活型间存在不同。对植物的开花物候,除已被证明的降水、温度和日照长度等环境因素的影响外,物种进化顺序也可能造成了它在植物种间、时间和空间上的变异。     

Relationships between the partial amino acid sequences of plastocyanin from members of ten families of flowering plants

Partial amino acid sequences of plastocyanin from 40 members of 10 families of flowering plants were analysed using a compatibility method based upon the suggestions of numerical taxonomists. In addition, sequences from members of the Fabaceae, Solanaceae and Apiaceae were analysed separately by an ancestral amino acid sequence method. The relationships suggested by the data are discussed with reference to the plant cytochrome-c data set and the use of amino acid sequence comparisons in phylogenetic studies generally.     

Simultaneous parsimony jackknife analysis of 2538rbcL DNA sequences reveals support for major clades of green plants, land plants, seed plants and flowering plants

The ever-larger data matrices resulting from continuing improvements in DNA sequencing techniques require faster and more efficient methods of phylogenetic analysis. Here we explore a promising new method, parsimony jackknifing, by analyzing a matrix comprising 2538 sequences of the chloroplast generbcL. The sequences included cover a broad taxonomic range, from cyanobacteria to flowering plants. Several parsimony jackknife analyses were performed, both with and without branch-swapping and multiple random addition sequences: 1) including all positions; 2) including only first and second codon positions; 3) including only third positions; and 4) using only transversions. The best resolution was obtained using all positions. Removal of third positions or transitions led to massive loss of resolution, although using only transversions somewhat improved basal resolution. While branch-swapping improved both resolution and the support found for several groups, most of the groups could be recovered by faster simple analyses. Designed to eliminate groups poorly supported by the data, parsimony jackknifing recognizes 1400 groups on the basis of allrbcL positions. These include major taxa such as green plants, land plants, flowering plants, monocots and eudicots. We include appendices of supported angiosperm families, as well as larger groups.     

Meta-analysis of phenotypic selection on flowering phenology suggests that early flowering plants are favoured

Flowering times of plants are important life-history components and it has previously been hypothesized that flowering phenologies may be currently subject to natural selection or be selectively neutral. In this study we reviewed the evidence for phenotypic selection acting on flowering phenology using ordinary and phylogenetic meta-analysis. Phenotypic selection exists when a phenotypic trait co-varies with fitness; therefore, we looked for studies reporting an association between two components of flowering phenology (flowering time or flowering synchrony) with fitness. Data sets comprising 87 and 18 plant species were then used to assess the incidence and strength of phenotypic selection on flowering time and flowering synchrony, respectively. The influence of dependence on pollinators, the duration of the reproductive event, latitude and plant longevity as moderators of selection were also explored. Our results suggest that selection favours early flowering plants, but the strength of selection is influenced by latitude, with selection being stronger in temperate environments. However, there is no consistent pattern of selection on flowering synchrony. Our study demonstrates that phenotypic selection on flowering time is consistent and relatively strong, in contrast to previous hypotheses of selective neutrality, and has implications for the evolution of temperate floras under global climate change.     

A re-examination of the root cortex in wetland flowering plants with respect to aerenchyma

AIMS: We review literature and present new observations on the differences among three general patterns of aerenchyma origin and their systematic distributions among the flowering plants, and we clarify terminology on root aerenchyma. SCOPE: From our own previous works and some new observations, we have analysed the root cortex in 85 species of 41 families in 21 orders of flowering plants that typically grow in wetlands to determine the characteristic patterns of aerenchyma. FINDINGS: A developmental and structural pattern that we term expansigeny, as manifested by honeycomb aerenchyma, is characteristic of all aquatic basal angiosperms (the Nymphaeales) and basal monocots (the Acorales). Expansigenous aerenchyma develops by expansion of intercellular spaces into lacunae by cell division and cell expansion. Schizogeny and lysigeny, so often characterized in recent reviews as the only patterns of root cortex lacunar formation, are present in most wetland plants, but are clearly not present in the most basal flowering plants. CONCLUSION: We conclude that expansigeny is the basic type of aerenchyma development in roots of flowering plants and that the presence of expansigenous honeycomb aerenchyma in root cortices was fundamental to the success of the earliest flowering plants found in wetland environments.     

高等植物开花诱导研究进展

高等植物由营养生长向生殖生长转换的过程称为开花诱导。开花诱导过程由遗传和外界环境两个因素决定, 受错综复杂的网络信号传导途径调控。近年来, 在双子叶模式植物拟南芥中, 开花诱导研究取得了很大进展, 探明了控制开花诱导的4条主要途径(光周期途径、春化途径、自主途径和GA途径)及调控机制。研究也表明, 开花基因在拟南芥、水稻以及其他高等植物之间具有很高的保守性。文章对相关研究的最新进展作一综述, 并指出了目前研究中存在的问题及相应的研究对策。     

The alien flowering plants of Mexico

A list of 618 species of alien flowering plants recorded for Mexico is presented; they are distributed in 355 genera and 87 families. The families with the largest number of species are Poaceae (171), Fabaceae sensu lato (57), Asteraceae (56), and Brassicaceae (45). The representation of most families with alien species in Mexico agrees with the average distribution frequencies estimated by Pysek (1998 ) for 26 floras throughout the World. Exceptions are an under‐representation of Asteraceae and an over‐representation of Poaceae. Most alien species (78.9%) in Mexico have their origin in the Old World; South America ranks second with 9.6%. As defined by Richardson et al. (2000 ), 19.8% of the alien species could be considered casual aliens and 80.2% of them naturalized. The proportion of alien species relative to the 22,968 native flowering plant species recorded for Mexico is 2.7%.     

低温处理种子对植物生长和开花习性影响的研究

本试验在对15种植物进行了低温处理种于对植物生长和开花习性的观测研究后发现,Bromus sterilis,Capsella bursa-pastoris 和Myosotis arvensis 3种植物的种子经低温处理后,其开花(小穗形成)时向提前,数量增加,枝条长度增加;同时,还讨论了在全球气候变暖的条件下,植物产生的这种现象可能对该种群的繁殖和演替带来的重大影响     

Evolutionary rates and species diversity in flowering plants

Genetic change is a necessary component of speciation, but the relationship between rates of speciation and molecular evolution remains unclear. We use recent phylogenetic data to demonstrate a positive relationship between species numbers and the rate of neutral molecular evolution in flowering plants (in both plastid and nuclear genes). Rates of protein and morphological evolution also correlate with the neutral substitution rate, but not with species numbers. Our findings reveal a link between the rate of neutral molecular change within populations and the evolution of species diversity.     

Comments on specific categories in flowering plants

The paper offers comments arising from the author's experience as a practising taxonomist on two aspects of what is often called the species problem: the reality of species and species as individuals. Three different meanings of reality are distinguished and discussed in this context: mental reality, biological reality and evolutionary reality. The author holds the view that, on all three definitions, species must be judged to be real. On the argument concerning species as individuals, the opinions ofHull, Ghiselin and others are carefully presented but rejected by the author, who retains the belief that species are classes and not individuals.Dedicated to the memory of JohnS. L. Gilmour.     

Epigenetic regulation of flowering time in polyploids

Polyploidy plays a significant role in the evolution of flowering plants. Understanding the effects of polyploidy on the epigenetic regulation of adaptive traits may resolve questions about the success of polyploids. One such trait, flowering time, has been the subject of several gene expression studies because it has one of the best characterized genetic networks and because polyploidy has a significant impact on generating variation in flowering time. Future research on the epigenetic consequences of polyploidy on flowering time should begin to examine natural variation in an ecological context, while continuing to make use of resynthesized polyploids.     

Evolution of incompatibility systems in plants: Complementarity and the mating locus in flowering plants and fungi

Summary The restriction of sexual pairing by a specificity gene is considered to be an ancient development in the plant kingdom. The diversity and general parallelism of incompatibility systems seen amongst the phyla at the present time can be rationalized in terms of the association of various derived forms of the ancestral specificity unit with differing spectra of accessory factors controlling sexual physiology in the different phyla. Sexual morphogenesis has become divided into distinct phases under the control of complementary genes. These phases are initiated by a regulatory system of Co-ordinator genes which control the order in which groups of morphogenetic genes are expressed during development. The entire sexual cycle will be completed only if all the complementary groups are activated in the appropriate sequence. The present article discusses essential features of the evolution of the breeding locus in different phyla. These features are consistent in themselves with the present data and are not dependent on the proposed ancient origin of the specificity gene.The above hypothesis throws light on the (1) evolution of the complex mating loci in flowering plants and fungi; (2) evolution of complementary incompatibility and heteromorphic incompatibility in flowering plants; (3) anomalous cross-compatibility behaviour of mutants in the fungus Schizophyllum commune; (4) nature of homothallism in higher fungi; (5) mode of origin of new functional self-incompatibility alleles; and (6) homogenic and heterogenic incompatibility.