Molecular systematics is widely used to determine organismal relationships. However, until now, systematics of angiosperms has mostly employed organellar genes, but these genes are generally inherited uniparentally, only partially reflecting the evolutionary history. In addition, chloroplast and mitochondrial genes are highly conserved, with limited numbers of phylogenetically informative characters. In contrast, nuclear genes are inherited biparentally and have relatively large numbers of informative sites, but only few nuclear genes have been utilized. In this work, sequences of five lowcopy nuclear genes were obtained in 17 species from Brassicaceae and used for phylogenetic analyses with the MaximumParsimony, MaximumLikelihood and Bayesian methods. Highly similar topologies were obtained using the five genes; in addition, compared with organellar genes, the nuclear genes had more phylogenetically informative sites and provided stronger supports. Specifically, the supporting values of all the nodes were 100% in MP trees using the five nuclear genes.Therefore,these five genes are excellent candidate marker genes for plant taxonomists who aim to resolve the relationships among lowlevel taxonomic hierarchies and might also be useful for DNA barcoding.
The origin and diversification of evolutionary novelties is one of the key issues in evolutionary developmental biology. Comparative analyses of the genetic mechanisms controlling early development of multicellular organisms have revealed that many morphological traits that are shared between distantly related organisms were controlled by conserved gene regulatory machinery (deep homology). The evolution of novel morphological traits often involves the cooption of preexisting genes and/or genetic regulatory circuits. Developmental gene regulatory networks are structurally and functionally modular. The property of modularity not only allows to alter development through dissociation and cooption of individual modules, but also enhances the evolvability of the network. Studying the evolutionary dynamics of gene networks and the evolution of development will extend our understanding of the mechanistic relationships between the processes of individual development and phenotypic change during evolution.
Flora Republicae Popularis Sinicae (FRPS) and Flora of China (FOC) are the Floras with the largest number of plant species recorded so far in the world, both of which have provided comprehensive scientific database for effective conservation and sustainable use of plant diversity and plant resources. Based on molecular data, the Angiosperm Phylogeny Group’s system of classification was proposed in 1998, and updated in 2003 and 2009, respectively. Such approach was also applied to other groups of vascular plants. As molecular systematics enters into a mature phase, the linear sequences derived from the new molecularbased framework classifications such as APG has been widely adopted to the study and application for entire vascular plants. In this paper, we compare Chinese vascular plants at the family level among Flora Republicae Popularis Sinicae, Flora of China and the new classifications. It is confirmed that there are 38 (out of a total of 48) families of lycophytes and ferns, 10 (out of 12) families of gymnosperms and 261 (out of 414) families of angiosperms in China. Although the total number of families of Chinese vascular plants does not vary as much as expected (300 in FRPS, and 309 in FOC and APG, respectively), the circumscriptions of a number of families changed greatly. In addition, we also discussed the changes of some important families of angiosperms in China.
Flower color is extremely diverse not only among flowering plants, but also in different populations and/or individuals of the same species (i.e., flower color polymorphism). There is also color variation within the same or different floral structures. Understanding the formation and maintenance of the diversity of flower color provides a cue to unveil the evolution of flowers. A long standing view considers flower color functioning as visual signal for pollinators, which may facilitate pollen transfer and increase foraging efficiency. Here we introduce four aspects of flower color diversity at interspecific and intraspecific levels, four different methodologies of studying color variation, discuss three hypotheses that explain the color variation. Future studies combining phylogenetic analysis and involving multiple factors including pollinators, herbivores and environments will be much helpful for a better understanding the diversity and evolution of flower color.
Leaf appendages (trichome, cuticle, papillae, stomatal apparatus) of Bretschneidera sinensis in different development stages were observed by paraffin section and scanning electron microscopy (SEM). The results showed that there were epidermal trichomes composed of one or several cells in a row on both leaf epiderms and veins. The density of the trichomes decreased with leaf development. The upper epiderm was covered with striated cuticles. The lower epiderm was covered with flowerlike papillae and the density also decreased with the development of leaf. The stomatal apparatus were anomocytic and found only on lower epidermis. By possessing similar papillae, combined with morphological, anatomical and molecular evidence, the close relationship between Bretschneidera sinensis and Akaniaceae was inferred. The characters of leaf appendages of Bretschneidera sinensis reflect its longterm adaption to environment.
Species delimitation is one of the most fundamental issues in biology and has recently drawn significant interest. A main reason for the increasing interests was the barcoding initiative associated rapid development of molecular techniques. One of the most important principles to diagnose species or species groups is to choose appropriate markers. However, incomplete linkage sorting and introgression, which are widespread phenomena in plants, present major obstacles in species delimitation. Recently, significant progress in our understanding of gene flow dependent introgression and species delimitation has been made both theoretically and empirically. In this paper, we reviewed the gene flow mediated speciation; evaluated the difference of introgression and incomplete linkage sorting; and finally concluded that species delimitation should be more effective with markers experiencing high levels of gene flow.
Reconstructing phylogenies at the community scale remains a fundamental but important work for current researches related to plant systematics, which can be facilitated due to the arising of plant DNA barcodes. We sampled, sequenced, and employed matK, rbcL and psbAtrnH to generate a multilocus barcode for 20ha Dinghushan subtropical forest dynamics plot, with 183 angiosperm species belonging to 110 genera (51 families from 24 orders) in South China. Compared to the twolocus barcode (rbcL+matK , and rbcL+psbAtrnH), the supermatrix of three barcode loci discriminated most of closed related taxa and generated a betterresolved community phylogeny utilizing an unconstraint approach in the Dinghushan plot, providing a first case that a subtropical forest plot with similarly limited taxon sampling with fewer orders and families could also provide significant congruence to the overall angiosperm phylogeny.
Based on 30 morphologic characters from 1500 specimens representing 13 species within the section Echinococcus, Euonymus, a numerical taxonomic study is presented. The result of cluster analysis showed that the distance between E.americanus and E.chenmoui is the nearest. Two series found by Blakelock in the section is not agreed. Some species which had confusing genetic relationship (E.hemsleyanus and E.angustatus, E.echinatus and E.subsessilis, E.hystrix and E.mengtseanus, E.acanthocarpus and E.tengyuehensis) showed far distance with each other. Characters which had obvious difference between these species were studied using analysis of variance, the result showed that there were significant difference on these characters (angle of leaf apex, length of leaf, angle between lateral vein and midrib, length of peduncle etc.). The result supported the conclusion that E.mengtseanus and E.tengyuehensis should be removed from the section. E.hemsleyanus and E.angustatus should be considered as separate species. Because there were no enough research data in crossed region, genetic relationship between E.echinatus and E.subsessilis should be researched in the future. The result of factor analysis showed that characters were independent in the experiment, 18 characters including length of leaf, angle between lateral vein and midrib, number of inflorescence branch, length of capsule (including prick) etc. were of significance for classification of section Echinococcus.
The biological invasion has become a major challenge on global development, especially for whole developing country like China. However, the background data of invasive species in China is still far from completed, and the relevant investigation of the Chinese invasive inforatmion has not been fully available yet today. The huge ecological and economic impacts caused by various invasive species have not been fully noticed or observed by the relative institutions and scientists, plus the ignorance of dangerous invasion with the introduction of alien species. Based on various literatures, the history and culture of invasive plant species, their invasive status and impact on ecological security and economic loss in China have been fully reviewed; and the problems existed and mangement measures of alien invasive plants in China have been fully proposed and summarized in order to provide basic information on the management of invasive plant species in China, and appeal to the government and the community to improve their RiskPrevention strategies and great sense of urgency with alien invasive plants in China.
