Table of Contents
  • Volume 56 Issue 1

    Cover illustration: Diversity of wild pears. Top left: Pyrus fedorovii in habitat (Prov. Vayotz Dzor, Herher gorge, Armenia). Top right: Flowers of P. spinosa. Bottom left: P. salicifolia (middle) and P. caucasica in habitat (Mtsheta-Mtianeti, Georgia). Bottom right: fruits of a P. salicifolia X P. demetrii hybrid. Photographs by Gerald Parolly. See Korotkova et al., pp. 35–47 in this issue.
      
      Review
    • Nizar Y. Saad
      2018, 56 (1): 1–13
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      The structural flexibility of RNA and its ability to store genetic information has led scientists to postulate that RNA could be the key molecule for the development of life on Earth, further leading to formulate the RNA world hypothesis that received a lot of success and acceptance after the discoveries of the last thirty-five years. Despite its highly structural and functional significance, the difficulty in synthesizing the four nucleobases that form the RNA polymer from the same primordial soup, its low stability, and limited catalytic repertoire, make the RNA world hypothesis less convincing even though it remains the best explanation for the origin of life. An increasing number of scientists are becoming more supportive of a more realistic approach explaining the appearance of life. In this review, I propose an enhanced explanation for the appearance of life supported by recent discoveries and theories. Accordingly, amino acids and peptides associated with RNA (e.g., ribonucleopeptides) might have existed at the onset of RNA and might have played an important role in the continuous development of self-sustaining biological systems. Therefore, in this review, I cover the most recent and relevant scientific investigations that propose a better understanding of the ribonucleopeptide world hypothesis and the appearance of life. Finally, I propose two hypotheses for a primitive translation machinery (PTM) that might have been formed of either a T box ribozyme or a ribopolymerase.
    • Research Articles
    • Qian Lan, Jian-Feng Liu, Sheng-Qing Shi, Nan Deng, Ze-Ping Jiang, Er-Mei Chang
      2018, 56 (1): 14–24
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      The study of the sexual systems of plants is very important for understanding their evolutionary process. Gnetum is a pivotal species in comprehending the seed plant phylogeny. However, the sexual systems of this genus are not fully understood. To investigate the sexual system of Gnetum, the anatomical structure, microstructure, and endogenous hormones were investigated from the differentiation of flower buds to fertilization in the floral organs of female and male of G. parvifolium (Warb.) C.Y. Cheng, widely distributed in the north of China. After 2 years of field investigations, the staminate strobili were observed on female plants for the first time and the abortive ovules were also found on male plants. In addition, high levels of gibberellin A3 and zeatin riboside led to masculinization, whereas a high level of indole-3-acetic acid favored feminization. A comprehensive analysis of the results indicates that G. parvifolium may not be completely dioecious on morphology, but female and male plants can only perform their own gender function, which would provide a better understanding of the diversity of sexual systems in Gnetum, and reproductive structures of seed plants.
    • Jianhua Li, K. Gregory Murray, Pan Li, Kenneth Brown
      2018, 56 (1): 25–34
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      Bocconia (10 species) and Macleaya (2 species) are two disjunct genera between South America and eastern Asia (EAS) in the Papaveraceae offering an opportunity to compare its biogeographic history with that of the well-known disjunction between EAS and eastern North American (ENA). Our phylogenetic analyses of the chloroplast matK and rbcL gene sequences of Ranunculales including two species of Macleaya and six species of Bocconia supported the monophyly of Bocconia, Macleaya, and Chelidonioideae to which Bocconia and Macleaya belong. Nucleotide sequences of matK, rbcL, and nrDNA ITS supported the sister relationship of Bocconia and Macleaya. Biogeographic analyses of Chelidonioideae using S-DIVA (statistical dispersal vicariance analysis) and DEC (dispersal extinction cladogenesis) methods inferred Eurasia as the most likely ancestral area of Bocconia and Macleaya and suggested no extinction events in either Bocconia or Macleaya. This agrees with the “Out-of-Asia” pattern of the EAS-ENA disjunction. Molecular dating of Ranunculales with fossil-based calibrations showed that Bocconia and Macleaya diverged in the late Eocene and early Oligocene, which is much earlier than most EAS-ENA disjunct taxa. The disjunction may have formed via long distance dispersal or boreotropical connections via the North Atlantic and Bering land bridges. Both Bocconia and Macleaya diversified in the late mid-Miocene, but Bocconia has apparently experienced a greater diversification probably aided by the evolution of the bird dispersal syndrome in fruit and seed after migration to South America. The greater diversification of Bocconia is also evidenced by the diverse leaf morphology and growth habit in response to colonization in various local habitats in South America.
    • Nadja Korotkova, Gerald Parolly, Anahit Khachatryan, Lusine Ghulikyan, Harutyun Sargsyan, Janna Akopian, Thomas Borsch, Michael Gruenstaeudl
      2018, 56 (1): 35–47
      With approximately 25 endemic species, the genus Pyrus (pears) is highly diverse in the Caucasus ecoregion. The majority of Caucasian pears inhabit xerophytic open woodlands or similar habitats, to which they display morphological adaptations, such as narrow leaves. The other species, both Caucasian and non-Caucasian taxa, mainly inhabit mesophytic forests and display broad leaves. Using a representative taxon sampling of Pyrus from the Caucasus, Europe and Asia, we reconstruct phylogenetic relationships in the genus based on multiple plastid regions. We also estimate the divergence times of major clades in Pyrus, reconstruct the evolution of leaf shapes, and discuss the emergence of xeromorphic leaf traits. Our results confirm the monophyly of Pyrus and the existence of two major clades: (a) an E Asian clade with a crown group age of 15.7 (24.02–8.37 95% HPD) My, and (b) a W Eurasian clade that comprises species from Europe, SW Asia and the Caucasus and that displays a slightly younger crown group of 12.38 (19.02–6.41 95% HPD) My. The existing infrageneric classification of Pyrus was found partially incongruent with the inferred phylogenetic trees. Several currently accepted species were not recovered as monophyletic, indicating that current species limits require re-evaluation. Ancestral character state reconstructions revealed several independent transitions from broad- to narrow-shaped leaves in Pyrus, probably via intermediate-shaped leaves.
    • Liu Yang, Guan-Song Yang, Hai-Ying Ma, Yue-Hua Wang, Shi-Kang Shen
      2018, 56 (1): 48–55
      Yunnanopilia longistaminea (W.Z. Li) C.Y. Wu & D.Z. Li, which is a controversial species in Opiliaceae, is treated as a variety of Champereia manillana (Blume) Merrill in the Flora of China and morphological analysis has produced conflicting results regarding its affinity to Melientha and Champereia. To determine the systematic position of Yunnanopilia in Opiliaceae, we selected two nuclear regions (internal transcribed spacer [ITS4-ITS5] and 18S rDNA) and four chloroplast regions (rbcL, matK, psbA-trnH, and trnS-trnG) to test the phylogenetics of the family Opiliaceae using maximum likelihood and Bayesian inference analysis. Morphological characteristics were also examined to clarify the similarities and differences among Y. longistaminea and two closely related species. Agonandra was located at the basal position in the family Opiliaceae; in the large clade including other remaining genera, two main clades were clearly identified and correlated with inflorescence morphological characteristics. All samples of Y. longistaminea formed a clade. Yunnanopilia, Melientha, and Champereia were more closely related than other genera of Opiliaceae. Yunnanopilia longistaminea was sister to M. suavis Pierre and was more closely related to M. suavis than to C. manillana. Morphological analysis also showed that differences in the inflorescences and flowers between Y. longistaminea and M. suavis were substantial enough to warrant the retention of Y. longistaminea in its current genus. Thus, we suggest that the monotypic Yunnanopilia be treated as a distinct genus and that the name Y. longistaminea should be adopted.
    • Chi-Toan Le, Bing Liu, Russell L. Barrett, Li-Min Lu, Jun Wen, Zhi-Duan Chen
      2018, 56 (1): 56–66
      Opiliaceae are a pantropical family of the Santalales mainly distributed in the Old World with only one genus in the neotropics. Opiliaceae have remained taxonomically unresolved and the generic relationships within the family have been disputed. Here we present molecular phylogenetic analyses of the family and its close relatives using a combined dataset of the nuclear ribosomal (small subunit rDNA and large subunit rDNA) and the chloroplast rbcL, matK, and trnL-F regions. We also carried out a morphological phylogenetic analysis using 24 characters for all the species of Opiliaceae and three species in Santalaceae s.l. and Strombosiaceae as outgroups. Molecular analyses strongly supported the monophyly of Opiliaceae. Agonandra Miers ex Benth. & Hook. f. is sister to all the other genera of Opiliaceae. The remaining genera form two major clades: the Opilia clade (including Cansjera Juss., Lepionurus Blume, Opilia Roxb., Pentarhopalopilia (Engl.) Hiepko, Rhopalopilia Pierre, and Urobotrya Stapf.), and the other consisting of Anthobolus plus the Champereia clade (including Champereia Griff., Melientha Pierre, and Yunnanopilia C. Y. Wu & D. Z. Li). We propose a new classification of Opiliaceae, recognizing 12 genera and four tribes, with the description of a new tribe, Champereieae Bing Liu, C. T. Le, L. M. Lu & Z. D. Chen.
    • S. Robbert Gradstein, Rui-Liang Zhu, Lei Shu, Álvaro J. Pérez
      2018, 56 (1): 67–75
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      Cololejeuneinae is the largest subtribe of the liverwort family Lejeuneaceae and the crown group of the family. The species often grow on the surfaces of living leaves and twigs or in swiftly running waters and many of them possess neotenic gametophytes, considered an adaptation to these extreme habitats. We describe a new, epiphyllous genus and species in Cololejeuneinae from the Western Cordillera of Ecuador, Reinerantha foliicola Gradst. & R.L.Zhu. Analysis of combined molecular datasets with parsimony, maximum likelihood and Bayesian methods revealed Reinerantha in a sister relationship to the large pantropical genus Diplasiolejeunea. Reinerantha differs from Diplasiolejeunea in leaf segmentation, epidermal wall thickening, stylus, male bracts and perianth keels, and is morphologically more similar to the genus Tuyamaella. In the molecular analysis, however, Reinerantha and Tuyamaella were resolved in different clades and not closely related. Tuyamaella is shown to be restricted to Asia; the report of Tuyamaella from South America (Peru) was erroneous and a case of mislabeling.
    • 2018, 56 (1): 76–77
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    • 2018, 56 (1): 78–78
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Editors-in-Chief
Song Ge
Jun Wen
Impact Factor
2.779
JCR 2019 IF ranking: 56/234 (Plant Sciences, top 23.72%, 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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