Table of Contents
  • Volume 48 Issue 4

    Cover illustration: Branching patterns in angiosperm inflorescences: the two extreme forms, racemose and cymose, and their combination in the thyrse. See ENDRESS, pp. 225–239 in this issue.
      
    Reviews
    Peter K. ENDRESS*
    2010, 48 (4): 225-239.
    Abstract   |   References   |   Full Text HTML   |   Full Text PDF   |   Save
    Terminology of inflorescence diversity has often been used in a confusing way in the literature, partly because it was based on uncritical and outdated definitions. Especially the terms cyme, thyrse, and panicle have been misused. Although a more critical classification worked out by several authors is available, it is unfortunately not in general use because most of the relevant publications are written in German. In addition, some terms have not been used in the same way by morphologists and developmental geneticists. The present review attempts to remedy the situation with a simple outline of a classification based on (1) different branching patterns, (2) differential elongation of axes of different orders, and (3) repetition of basic ramification patterns in different ways. Racemose and cymose branching are two extreme patterns, the former with limitation of axial orders to two, the second with limitation of lateral axes of each order to two. In a branching system a sequence of racemose → cymose, and, within the cyme, of dichasial → monochasial, is common, but the reverse sequence is not known to occur. Systematic and evolutionary aspects of inflorescences are briefly discussed. Branching patterns are often stable in larger clades. Inflorescences of mutants studied in developmental genetic studies are mainly altered in flower or branch numbers or relative branch length but not in branching patterns. This is also a contribution toward the goal of a unified terminology for the different fields of biology dealing with inflorescences.
    Research Articles
    Jinling HUANG, Guiling SUN,Da-Ming ZHANG
    2010, 48 (4): 240-248.
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    Much of the recent progress in understanding angiosperm phylogeny has been achieved using multigene or plastid genome datasets. However, the size of a dataset required to achieve sufficient resolution is largely unclear. The ycf2 gene is the largest plastid gene in angiosperms and it was used as part of multigene datasets in several earlier investigations on angiosperm relationships. In this study, we show that the ycf2 gene alone can provide a generally well-supported phylogeny that is consistent with those inferred from the most comprehensive multigene or plastid genome datasets. The phylogenetic signal of the ycf2 gene is likely derived from the combination of its long sequence length and low rate of nucleotide substitution. The ycf2 gene may provide a low-cost alternative to comprehensive multigene or genome datasets for investigating angiosperm relationships.
    Xia YANG,Hong CUI,Zu-Li YUAN, Yin-Zheng WANG
    2010, 48 (4): 249-256.
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    CYC-like genesarewidely conserved in controlling floral dorsoventral asymmetry (zygomorphy) through persistent expressions in corresponding domains in core eudicots.To understand how CYC-like gene expressionsare maintained during flower development, we selected Chirita heterotrichaas materials andisolatedthe promoter sequences of ChCYC1C and ChCYC1D genes, homologs of CYC, by inverse PCR. Further promoter analyses led to the identification of a putative cis-regulatory element in each promoter matching the consensus DNA binding site for Antirrhinum CYC protein: GGCCCCTC at –165 for ChCYC1C, and GGCCCCCC at –163 for ChCYC1D. This result indicates that both ChCYC1C and ChCYC1D genes probably have evolved autoregulatory loops to sustain their expressions in developing flowers. We also isolated the coding and promoter sequences of ChRAD gene, a homolog of Antirrhinum RAD. Promoter analysis showed that ChRAD gene promoter also contained a putative CYC-binding site (GGCCCAC at –134). Therefore, ChRAD is likely a direct target of ChCYC1 genes, which is similar to Antirrhinum RAD. The above results imply that the establishment of floral zygomorphy in Chirita might have been achieved by the evolution of autoregulatory loop of CYC-like genes, which was probably accompanied by simultaneous co-option of RAD-like gene into their regulatory network.
    Li-Yan ZENG, Ling-Li XU, Shao-Qing TANG, Tashi TERSING, Yu-Peng GENG, Yang ZHONG
    2010, 48 (4): 257-264.
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    The fine-scale spatial genetic structure (SGS) of alpine plants has received increasing attention, from which the seed and pollen dispersal can be inferred. However, estimation of SGS may depend strongly on the sampling strategy, including the sample size and spatial sampling scheme. Here, we examined the effects of sample size and three spatial schemes (i.e., simple-random, line-transect, and random-cluster sampling) on the estimation of SGS in Androsace tapete, an alpine cushion plant endemic to Qinghai-Tibetan Plateau. Using both real data and simulated data of dominant molecular markers, we show that: 1) SGS is highly sensitive to sample strategy especially when the sample size is small (e.g., below 100); 2) the common used SGS parameter (i.e., the intercept of autocorrelogram) is more susceptible to sample error than a new developed Sp statistic; 3) the random-cluster scheme is susceptible to obvious bias in parameter estimation even when the sample size is relatively large (e.g., above 200). Overall, the line-transect scheme is recommendable, which performs slightly better than the simple-random scheme in parameter estimation and is more efficient to encompass broad spatial scales. The consistency between simulated data and real data implies that these findings might hold true in other alpine plants and more species should be examined in future work.
    Zhi-Yuan DU, Chun-Feng YANG, Jin-Ming CHEN, You-Hao GUO, A. B. KADIRI
    2010, 48 (4): 265-270.
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    Potamogeton is a genus well known for the occurrence of interspecific hybrids. The linear-leaved Potamogeton species commonly have highly variable morphological characteristics. Their hybrids often show the similar vegetative characters of their parental species. Their identification based solely on morphology is not always conclusive. In order to clarify whether there existed any hybrids from the linear-leaved Potamogeton plants collected in China, we used internal transcribed spacers (ITS) of nuclear ribosomal DNA and chloroplast rbcL gene sequences to identify the hybrids. Using ITS sequence additivity, we identified four hybrids, P. orientalis (P. pusillus ×P. oxyphyllus), P. pusillus × P. berchtoldii, P. foliosus × P. octandrus, and P. cristatus ×P. octandrus. The latter three hybrids should be considered as new hybrids in Potamogeton. The maternal parents of the four hybrids were confirmed by chloroplast rbcL gene sequence.
    Rubén TORICES*
    2010, 48 (4): 271-278.
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    New inference techniques, as supertrees, have improved the construction of large phylogenies helping to reveal the tree of life. In addition, these large phylogenies have enhanced the study of other evolutionary questions as whether traits have evolved in a neutral or adaptive way, or what factors have influenced diversification. However, supertrees usually lack branch lengths, which are necessary to study all these issues. Here, divergence times within the largest family of flowering plants, Asteraceae, are reviewed for estimating time-calibrated branch lengths in the supertree of this lineage. An inconsistency between estimated dates of basal branching events and the earliest asteraceous fossil pollen record was detected. In addition, I explored how different methods of branch lengths assignment may influence the total number of transitions between states in the reconstruction of sexual system evolution in Asteraceae. At least for this data set, different branch length assignation approaches only influenced maximum likelihood reconstructions but not Bayesian ones. The selection of different branch lengths information, therefore, is not arbitrary and it should be carefully assessed at least when ML approaches are being used. The reviewed divergence times and the estimated time-calibrated branch lengths provide a useful tool for future phylogenetic comparative and macroevolutionary studies of Asteraceae.
    Hong-Ping MU,Lan HONG,Hong-Lin CAO,Zheng-Feng WANG,Zhong-Chao LI,Hao SHEN,Zhang-Ming WANG,Wan-Hui YE
    2010, 48 (4): 279-285.
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    Ardisia crenata Sims, one of the most widely distributed Ardisia in the world, is an important ornamental and medicinal plant species. Using 7 polymorphic nuclear microsatellite loci, we studied the genetic variation of 20 natural populations of A. crenata across its distribution centre, the south China. Significant deviation from Hardy-Weinberg equilibrium in all populations and at all loci were detected, and the fixation index was high (FIS = 0.725), indicating that inbreeding may be dominant in the mixed mating system of this self-compatible species. The average genetic diversity within populations was relatively low (HS = 0.321). There was significant genetic differentiation among populations (FST = 0.583), which may be resulted from high level of inbreeding and low level of gene flow. A. crenata in south China can be roughly divided into eastern group and western group, consistent with the floristic division of Sino-Himalayan forest subkingdom and Sino-Japanese forest subkingdom. It was suggested that there may be separated glacial refugia in each region.
    ,Jian-Wei ZHANG,Jian-Xin YAO,Chia-Jui CHEN,Cheng-Sen LI
    2010, 48 (4): 286-301.
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    A new cycad, Leptocycas yangcaogouensis sp. nov., is found in the Late Triassic sediments from the western Liaoning, China. The pinnately compound leaves (Pseudoctenis type) are screwed in a crown on the stem top. The leaflets are linear, with parallel veins and decurrent bases on rachis. The leaf bases are persistent. The cataphylls intermix with leaves. The female cone is ovoid in shape. The characteristics of the new plant are more similar to those of Leptocycas gracilis, a Triassic cycad from North America. But the new one differs from L. gracilis in the size of stem (7×8 cm vs. 3×5 cm in diameter), leaves (100×16 cm vs. 30×7 cm in length × width) and leaf density (4–6 bases vs. 1–2 bases / per 1 cm long) on the stem. Both L. gracilis and L. yangcaogouensis, possessing the leaves of Pseudoctenis type, show their closer relationship to the extant Dioon of Zamiaceae. This work provides the evidence for the origin of genus of Dioon, which may come from Triassic plant of Leptocycas. It would be assumed that the extent cycads in Zamiaceae originate from the pteridosperms in Late Paleozoic, and evolve through the stage of L. gracilis and L. yangcaogouensis in Late Triassic, and then reach to the extant Dioon.
    Wen-Yi GUO, Jian YANG, Dmitry GROMYKO, Albert G. ABLAEV, Qing WANG, Cheng-Sen LI
    2010, 48 (4): 302-308.
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    Cercidiphylloxylon spenceri (Brett) Pearson is described from the Lizigou Formation, Palaeocene in China. The growth rings are distinct; pores are diffuse, solitary, with somewhat angular outlines in cross section; vessel elements long with long scalariform perforation plates; intervessel pitting is opposite to scalariform; fiber-tracheids are present; axial parenchyma is scarce; rays are mostly biseriate and heterogeneous. All wood characters of the fossil specimen fall into the range of those of extant Cercidiphyllum (Cercidiphyllaceae). The finding is one of the earliest fossil wood records of Cercidiphyllaceae.
Editors-in-Chief
Song Ge
Jun Wen
Impact Factor
4.040
JCR 2018 IF ranking: 22/228 (Plant Sciences, top 9.4%, Q1 quartile)
Journal Abbreviation: J Syst Evol
ISSN: 1674-4918 (Print)
1759-6831 (Online)
CN: 11-5779/Q
Frequency: Bi-monthly

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