Table of Contents

14 November 2012, Volume 50 Issue 6
Cover illustration: The American lotus, Nelumbo lutea, is one of the two living fossils in family Nelumbonaceae. Although the family has diverged from its relatives for more than 100 million years, the chloroplast genome of N. lutea is of a typical structure of plants and the American lotus has just split from its Asian counterpart, N. nucifera, for a few million years. For detailed chloroplast genome of N. lutea and molecular dating of lotus family and other angiosperms, please see XUE e [Detail] ...
    Research Articles
  • Jian-Hua XUE,Wen-Pan DONG,Tao CHENG,Shi-Liang ZHOU
    J Syst Evol. 2012, 50(6): 477-487.
    Nelumbonaceae is a morphologically unique family of angiosperms and was traditionally placed in Nymphaeales; more recently, it was placed in Proteales based on molecular data, or in an order of its own, Nelumbonales. To determine the systematic position of the family and to date the divergence time of the family and the divergence time of its two intercontinentally disjunct species, we sequenced the entire chloroplast genome of Nelumbo lutea and most of the chloroplast genes of N. nucifera. We carried out phylogenetic and molecular dating analyses of the two species and representatives of 47 other plant families, representing the major lineages of angiosperms, using 83 plastid genes. The N. lutea genome was 163 510 bp long, with a total of 130 coding genes and an overall GC content of 38%. No significant structural differences among the genomes of N. lutea, Nymphaea alba, and Platanus occidentalis were observed. The phylogenetic relationships based on the 83 plastid genes revealed a close relationship between Nelumbonaceae and Platanaceae. The divergence times were estimated to be 109 Ma between the two families and 1.5 Ma between the two Nelumbo species. The estimated time was only slightly longer than the age of known Nelumbo fossils, suggesting morphological stasis within Nelumbonaceae. We conclude that Nelumbonaceae holds a position in or close to Proteales. We further conclude that the two species of Nelumbo diverged recently from a common ancestor and do not represent ancient relicts on different continents.
  • Zhong-Lai LUO, Shi CHEN, Dian-Xiang ZHANG
    J Syst Evol. 2012, 50(6): 488-495.
    Animal-pollinated plant species modulate the presentation of pollinator rewards to maximize reproductive success. In plants providing pollen as the only reward for pollinators, it is usually difficult to unravel the dual roles of reward presentation and the realization of male and female functions (pollen removal and deposition). Exploiting the two types of anther in the androecia of Melastoma malabathricum L., we examined whether the removal of pollen for reward is regulated primarily to favor male function or female function. Pollen removal by carpenter bees from the feeding and pollination anthers, as well as pollen deposition on the stigmas, were quantified during anthesis of M. malabathricum. There was no significant difference in pollen removal rates from the feeding and pollination anthers of M. malabathricum between the onset of anthesis and flower wilting. The stigmatic pollen loads exceeded the ovule number after three sonication bouts, and female function was satisfied earlier than male function. The results support the hypothesis that the presentation of pollination reward in this species is regulated primarily to favor the expression of male function, rather than female function, in agreement with the pollen-donation hypothesis. A cooperative relationship between the feeding and pollination anthers was demonstrated in heterantherous flowers, which optimizes the balance in investments between pollinator rewards and “functional pollen” for gene transfer.
  • Magdy Hussein ABD EL-TWAB
    J Syst Evol. 2012, 50(6): 496-501.
    Molecular cytogenetics studies of A-T-rich regions, telomeres, and 5S and 45S rDNA sites on the chromosomes of Reichardia tingetana Roth (2n= 16; diploid) were done using 4′, 6-diamidino-2-phenylindole (DAPI) and fluorescence in situ hybridization (FISH). The species were collected from three geographically isolated populations at Borg El Arab (salt marsh habitat), and Rashed and Shosha (sandy clay habitats) in Egypt. The three populations showed the chromosome number of all plants are diploid except for two tetraploid samples from Shosha. Plants from both Rashed and Shosha showed similarity in the distribution of six DAPI bands on six chromosomes, whereas those of Borg El Arab showed a distribution of 16 bands on 14 chromosomes. The FISH signals of the telomeres, and 5S and 45S rDNA, were at the telomeres of all chromosomes, two interstitial, and four terminal, respectively. The combination of DAPI and FISH showed colocalization of the DAPI bands with two 5S and two 45S rDNA loci. The increased number of DAPI bands in the cytotypes from the salt marsh habitat could indicate natural genetic adaptation through increasing the heterochromatin of A-T-rich regions.
  • Bin WANG, Ning ZHANG, Chun-Ce GUO, Gui-Xia XU, Hong-Zhi KONG, Hong-Yan SHAN
    J Syst Evol. 2012, 50(6): 502-511.
    APETALA1 (AP1) and CAULIFLOWER (CAL) are a pair of paralogous genes that were generated through the pre-Brassicaceae whole-genome duplication event. AP1 and CAL have both partially redundant and unique functions. Previous studies have shown that the K and C regions of their proteins are essential for the functional divergence. However, which differences in these regions are the major contributors and how the differences were accumulated remain unknown. In the present study, we compared the sequences of the two proteins and identified five gaps and 55 amino acid replacements between them. Investigation of genomic sequences further indicated that the differences in the proteins were caused by non-synonymous substitutions and changes in exon–intron structures. Reconstruction of three-dimensional structures revealed that the sequence divergence of AP1 and CAL has resulted in differences between the two in terms of the number, length, position and orientation of α-helices, especially in the K and C regions. Comparisons of sequences and three-dimensional structures of ancestral proteins with AP1 and CAL suggest that the ancestral AP1 protein experienced fewer changes, whereas the ancestral CAL protein accumulated more changes shortly after gene duplication, relative to their common ancestor. Thereafter, AP1-like proteins experienced few mutations, whereas CAL-like proteins were not conserved until the diversification of the Brassicaceae lineage I. This indicates that AP1- and CAL-like proteins evolved asymmetrically after gene duplication. These findings provide new insights into the functional divergence of AP1 and CAL genes.
  • Neetin DESAI, Hemant KAWALKAR, Ghansham DIXIT
    J Syst Evol. 2012, 50(6): 512-518.
    The taxonomic position and genetic relationship within Indian Drimia species is controversial due to their morphological similarities and genomic complexities. The present work gives an insight on the genetic relationship between Indian Drimia species on the basis of their karyotype, pollen morphology, flower opening characteristics, hybridization behavior, and by use of DNA sequence of two molecular markers (internal transcribed spacers [ITS] and maturase K [matK]). The karyotypic studies of Indian Drimia species revealed various polyploid forms making their identification and delimitation more difficult. The five species of Indian Drimia are grouped into two complexes, indica complex and wightii complex on the basis of their pollen morphology, karyotype, and hybridization behavior. These two groups were found to be evolving separately. The cytomorphological studies of wightii complex revealed that it is evolving through polyploid and chromosome repatterning, while indica complex have adapted polyploid as well as hybridization for evolution. Phylogeny obtained from DNA sequences of molecular markers (ITS and matK) confirmed that the indica complex and wightii complex are evolving parallely, by grouping them in two clusters. Thus, a combination of conventional and molecular methods proved to be of great use for delimiting a small but complex group of Indian Drimia species.
  • Yan-Wen ZHANG, Xing-Nan ZHAO, Sheng-Jun HUANG, Li-Hui ZHANG, Ji-Min ZHAO
    J Syst Evol. 2012, 50(6): 519-526.
    Floral color changes are common in Weigela and the retention of post-change flowers has been interpreted as a mechanism to increase attractiveness from a long distance and shorten pollinators’ lingering time on the inflorescence(s) of individual plants. In the present study, we investigated the temporal pattern of floral color change and time required for pollen tube growth in the shrub Weigela japonica var. sinica. Over the 4-day anthesis, the color of the corolla in this species changes from white to red and the color cue changes from yellow to purple. The duration of both the white phase and the intermediate phase is approximately 1 day and the duration of the red phase is approximately 2 days. Our studies showed that color change in Weigela japonica var. sinica is age-dependent but independent of pollinator visits and flower pollination. Post-change flowers lost most of both the male and female residual reproductive ability and retained no rewards for pollinators. It took at least 3 days for a pollen tube to grow to the ovules and achieve fertilization. Thus, retention of post-change flowers is necessary for the completion of pollen tube growth. Our results indicate that the temporal pattern of color change and time requirement for pollen tube growth are most likely related events.
  • Zhao-Ming CAI, Yu-Xiao ZHANG, Li-Na ZHANG, Lian-Ming GAO, De-Zhu LI
    J Syst Evol. 2012, 50(6): 527-539.
    Bambusoideae is an important subfamily of the grass family Poaceae that has considerable economic, ecologic and cultural value. In addition, Bambusoideae species are important constituents of the forest vegetation in China. Because of the paucity of flower-bearing specimens and homoplasies of morphological characters, it is difficult to identify species of Bambusoideae using morphology alone, especially in the case of temperate woody bamboos (i.e. Arundinarieae). To this end, DNA barcoding has shown great potential in identifying species. The present study is the first attempt to test the feasibility of four proposed DNA barcoding markers (matK, rbcL, trnHpsbA, and internal transcribed spacer [ITS]) in identifying 27 species of the temperate woody bamboos. Three plastid markers showed high levels of universality, whereas the universality of ITS was comparatively low. A single plastid marker provided low levels of discrimination success at both the genus and species levels (<12%). Among the combinations of plastid markers, the highest discriminatory power was obtained using the combination of rbcL+matK (14.8%). Using a combination of three markers did not increase species discrimination. The nuclear region ITS alone could identify 66.7% of species, although fewer taxa were included in the ITS analyses than in the plastid analyses. When ITS was integrated with a single or combination of plastid markers, the species discriminatory power was significantly improved. We suggest that a combination of rbcL+ ITS, which exhibited the highest species identification power of all combinations in the present study, could be used as a potential DNA barcode for temperate woody bamboos.
  • Cong-Hui XIONG,De-Ming WANG, Qi WANG,Mei-Cen MENG
    J Syst Evol. 2012, 50(6): 540-549.
    Kunia venusta gen. et sp. nov. is reported from the late Middle Devonian (Givetian) Haikou Formation near Kunming City, Yunnan Province, China. This plant has three orders of naked axes that divide pseudomonopodially. The second- and third-order axes occur in a helix. Fertile appendages are distantly spaced and helically inserted to the third-order axis; they comprise equally dichotomous branches terminated by two clusters of paired and fusiform sporangia. Sterile appendages are dichotomous and distally recurved. A comparison is made with the basal euphyllophytes including the trimerophytes, cladoxylopsids, zygopterids, stauropterids, and some relevant genera of uncertain affinity. The new plant resembles them in dichotomous appendages with terminal elongated sporangia, but differs mainly in the three orders of pseudomonopodial axes bearing helical laterals. It is thus placed in the Euphyllophytina as incertae sedis. It is suggested that an evolutionary divergence in the branching pattern and appendage morphology might have occurred in the Middle Devonian euphyllophytes, that is, maintaining three dimensions versus yielding more or less planation.
  • Li-Song WANG
    J Syst Evol. 2012, 50(6): 550-572.
    A revision of the East Asian genus Pternopetalum Franch. is presented recognizing 15 species and proposing 14 new synonyms. Pternopetalum filicinum (Franch.) Hand.-Mazz., P. asplenioides (H. Boissieu) Hand.-Mazz., P. heterophyllum Hand.-Mazz., and P. tanakae var. fulcranium Y. H. Zhang are merged with P. tanakae (Franch. & Savatier) Hand.-Mazz. Pternopetalum wolffianum (Fedde ex H. Wolff) Hand.-Mazz., P. yiliangense Shan & Pu, P. vulgare var. strigosum Shan & Pu, and P. vulgare var. acuminatum C. Y. Wu ex Shan & Pu are reduced to P. vulgare (Dunn.) Hand.-Mazz. Pternopetalum botrychioides var. latipinulatum Shan and P. affinum (Fedde ex H. Wolff) M. Hiroe are combined with P. botrychioides (Dunn) Hand.-Mazz. Pternopetalum longicaule Shan and P. mairei (Diels ex H. Wolff) Hand.-Mazz. are merged with P. delavayi (Franch.) Hand.-Mazz. Pternopetalum trachycarpum C. Y. Wu ex Shan & Z. H. Pan is reduced to P. trichomanifolium (Franch.) Hand.-Mazz. An identification key, descriptions, and distribution maps are provided.