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25 June 2017, Volume 39 Issue 03
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  • Articles
    Evolution of biogeographic disjunction between eastern Asia and North America in Chamaecyparis: Insights from ecological niche models
    Ping Liu, Jun Wen, Tingshuang Yi
    2017, 39(03):  111-116.  doi:10.1016/j.pld.2017.04.001
    Abstract ( 41 )   HTML ( )   PDF (2450KB) ( 4 )   Save
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    The disjunct distribution of plants between eastern Asia (EA) and North America (NA) is one of the most well-known biogeographic patterns. However, the formation and historical process of this pattern have been long debated. Chamaecyparis is a good model to test previous hypotheses about the formation of this disjunct pattern as it contains six species disjunctly distributed in EA, western North America (WNA) and eastern North America (ENA). In this study, we applied ecological niche models to test the formation of the disjunct pattern of Chamaecyparis. The model calibrated with the EA species was able to predict the distribution of eastern NA species well, but not the western NA species. Furthermore, the eastern Asian species were shown to have higher niche overlap with the eastern North American species. The EA species were also shown to share more similar habitats with ENA species than with WNA species in the genus. Chamaecyparis species in WNA experienced a significant niche shift compared with congeneric species. Chamaecyparis had a low number of suitable regions in Europe and the middle and western NA during the Last Glacial Maximum (LGM) period, and became extinct in the former region whereas it retains residual distribution in the latter. The extirpations in western NA and Europe in response to the late Neogene and Quaternary climatic cooling and the more similar habitats between ENA and EA ultimately shaped the current intercontinental disjunct distribution of Chamaecyparis. Both current hypotheses may be also jointly applied to explain more eastern Asian and eastern North American disjunctions observed today.
    High molecular karyotype variation revealed in indigenous Elymus nutans in the Qinghai Plateau
    Quanwen Dou, Feng Yu, Yuan Li, Yanyan Zhao, Ruijuan Liu
    2017, 39(03):  117-122.  doi:10.1016/j.pld.2017.05.003
    Abstract ( 28 )   HTML ( )   PDF (2936KB) ( 5 )   Save
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    The karyotypes of 27 individuals of Elymus nutans from eight wild populations in the Qinghai Plateau were analyzed using sequential FISH and GISH. High FISH pattern polymorphism and karyotype variation were detected within and among populations. The chromosome variations were mainly characterized as repeat deletions and amplifications along with inter-genomic translocations. The chromosomes of the St and Y genomes demonstrated higher polymorphism than those of the H genome. Six different inter-genomic translocations were identified in 33.3% of individuals; type I and II translocations were detected with higher frequency. Further analysis revealed that type I and II translocations were distributed in different geographic regions. The origin of high karyotype variation of E. nutans in the Qinghai plateau is further discussed.
    Molecular cloning and expression analysis of turnip (Brassica rapa var. rapa) sucrose transporter gene family
    Yuanyuan Liu, Xin Yin, Ya Yang, Chuntao Wang, Yongping Yang
    2017, 39(03):  123-129.  doi:10.1016/j.pld.2017.05.006
    Abstract ( 21 )   HTML ( )   PDF (2857KB) ( 4 )   Save
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    In higher plants, sugars (mainly sucrose) are produced by photosynthetically assimilated carbon in mesophyll cells of leaves and translocated to heterotrophic organs to ensure plant growth and development. Sucrose transporters, or sucrose carriers (SUCs), play an important role in the long-distance transportation of sucrose from source organs to sink organs, thereby affecting crop yield and quality. The identification, characterization, and molecular function analysis of sucrose transporter genes have been reported for monocot and dicot plants. However, no relevant study has been reported on sucrose transporter genes in Brassica rapa var. rapa, a cruciferous root crop used mainly as vegetables and fodder. We identified and cloned 12 sucrose transporter genes from turnips, named BrrSUC1.1 to BrrSUC6.2 according to the SUC gene sequences of B. rapa pekinensis. We constructed a phylogenetic tree and analyzed conserved motifs for all 12 sucrose transporter genes identified. Real-time quantitative polymerase chain reaction was conducted to understand the expression levels of SUC genes in different tissues and developmental phases of the turnip. These findings add to our understanding of the genetics and physiology of sugar transport during taproot formation in turnips.
    Occurrence of internally ovipositing non-agaonid wasps and pollination mode of the associated agaonid wasps
    Xinmin Zhang, Darong Yang
    2017, 39(03):  130-134.  doi:10.1016/j.pld.2017.04.002
    Abstract ( 25 )   HTML ( )   PDF (1468KB) ( 4 )   Save
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    Figs (Ficus, Moraceae) and their pollinating fig wasps (Hymenoptera, Agaonidae, Chalcidoidea) are a striking example of obligate mutualism and coevolution. Agaonid females enter the figs to lay their eggs, but also actively or passively transport pollen into the figs at the same time. We examined eight related fig tree species pollinated by host specific Eupristina agaonids to determine the relationships between pollination mode, host pollen, ovule ratios and the ability of the figs to recruit additional non-agaonid pollinators. Uniquely amongst the eight Eupristina species, the pollinator of Ficus curtipes has non-functional pollen pockets and no coxal combs, showing that it pollinates passively. Reflecting this, the anther-to-ovule ratio of F. curtipes is unusually high.In addition to the agaonids, figs support many species of ‘non-pollinating fig wasps’ (NPFW) that are typically ovule gallers or parasitoids. These mainly oviposit from outside the figs but there are a few species of NPFW that are like agaonids and enter the figs to oviposit. Two of the eight Eupristina pollinated fig trees support host specific internally-ovipositing fig wasps belonging to the chalcidoid genera Diaziella (Sycoecinae) and Lipothymus (Otitesellinae). Reflecting the trees' pollination modes, these fig wasps act as supplementary pollinators of F. curtipes, but not of Ficus glaberrima, where agaonid pollination is active.
    Distribution of Holttumochloa (Poaceae: Bambusoideae) in China with description of a new species revealed by morphological and molecular evidence
    Mengyuan Zhou, Jingxia Liu, Yiwen Liang, Dezhu Li
    2017, 39(03):  135-139.  doi:10.1016/j.pld.2017.05.001
    Abstract ( 28 )   HTML ( )   PDF (15013KB) ( 11 )   Save
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    Holttumochloa has previously only been recorded from Malaysia. Here we describe and illustrate a new species, Holttumochloa hainanensis sp. nov., from the lowland montane forests of Diaoluo Mountain on the Island of Hainan, South China. Morphologically, H. hainanensis is similar to Holttumochloa korbuensis, but can be clearly distinguished from it in having larger culms covered by white wax, longer leaf blades, larger pseudospikelets and anthers. Furthermore, molecular phylogeny based on the nuclear gene GBSSI corroborates the identification of the new species and its affinity. The biogeographical significance of the new record of Holttumochloa in South China is also highlighted in this study.
    Current re-vegetation patterns and restoration issues in degraded geological phosphorus-rich mountain areas: A synthetic analysis of Central Yunnan, SW China
    Kai Yan, Sailesh Ranjitkar, Deli Zhai, Yunju Li, Jianchu Xu, Bo Li, Yang Lu
    2017, 39(03):  140-148.  doi:10.1016/j.pld.2017.04.003
    Abstract ( 28 )   HTML ( )   PDF (8349KB) ( 8 )   Save
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    China has the largest area of inland geological phosphorus-rich (GPR) mountains in the world, where vegetation restoration is key to safeguarding the environment. We reviewed the published literature and collected new data in order to analyze re-vegetation patterns and the status of plant communities in central Yunnan. The aim of our analysis was to suggest future improvements to restoration strategies in GPR mountain regions. Our results showed that spontaneous recovery was the most widespread type of restoration. N-fixing species such as Coriaria nepalensis and Alnus nepalensis play a vital role in succession. In the past, monoculture tree plantation was the primary method used in afforestation activities in central Yunnan; in recent years however, several different methods of restoration have been introduced including the use of agroforestry systems. For practical restoration, we found that spontaneous recovery was capable of delivering the best results, but that during its early stages, restoration results were affected by several factors including erosion risk, the origin of propagates and environmental variation. In contrast, methods employing human-made communities performed better in their early stages, but were constrained by higher costs and vulnerability to degradation and erosion. The use of N-fixing species such as A. nepalensis and Acacia mearnsii in plantations were unsuccessful in restoring full ecosystem functions. The success of restoration activities in GPR mountain regions could be improved through the following measures: (1) developing a better understanding of the respective advantages and disadvantages of current natural and human-engineered restoration approaches; (2) elucidating the feedback mechanism between phosphorus-rich soil and species selected for restoration, especially N-fixing species; (3) introducing market incentives aimed at encouraging specific restoration activities such as agroforestry, and improving the industry value chain.
    Lost in transition: Forest transition and natural forest loss in tropical China
    Deli Zhai, Jianchu Xu, Zhicong Dai, Dietrich Schmidt-Vogt
    2017, 39(03):  149-153.  doi:10.1016/j.pld.2017.05.005
    Abstract ( 33 )   HTML ( )   PDF (878KB) ( 1 )   Save
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    The term forest transition refers to a change in forest cover over a given area from a period of net forest area loss to a period of net gain. Whether transitioning from deforestation to reforestation can lead to improved ecosystem services, depends on the quality and characteristics of the newly established forest cover. Using publicly available data, we examine forest transition in two regions of tropical China: Hainan Island and Xishuangbanna. We found that the overall increase of forest cover in both areas during the 1980s was due to an increase in plantation forests rather than to increases in the area covered by natural forest. We also found a time lag between the increase in overall forest cover and an increase in natural forest. On Hainan Island, natural forest continued to decline beyond the point in time when overall forest cover had started to increase, and only began to recover ten years after the turning point in 1978. In Xishuangbanna, where the transition point occurred ten years later, the decline of natural forest cover is still going on. These divergent trends underlying forest transition are concealed by the continued practice to apply the term “forest” broadly, without distinguishing between natural forests and planted forests. Due to the use of undiscriminating terminology, the loss of natural forest may go unnoticed, increasing the risk of plantation forests displacing natural forests in the course of forest transition. Our findings are important for programs related to forest management and ecosystem services improvement, including reforestation and Payments for Ecosystem Services programs.
    Localization of a defensive volatile 4-hydroxy-4-methylpentan-2-one in the capitate glandular trichomes of Oenothera glazioviana
    Yanyun Tan, Desen Li, Juan Hua, Shihong Luo, Yan Liu, Shenghong Li
    2017, 39(03):  154-159.  doi:10.1016/j.pld.2017.05.004
    Abstract ( 8 )   HTML ( )   PDF (2289KB) ( 5 )   Save
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    Glandular trichomes of plants produce a wide variety of secondary metabolites which are considered as major defensive chemicals. The capitate glandular trichomes of Oenothera glazioviana (Onagraceae) were collected with laser microdissection and analyzed by gas chromatography–mass spectrometry. The volatile compound 4-hydroxy-4-methylpentan-2-one (1) was identified. We found that compound 1 displays antimicrobial, insecticidal, and phytotoxic activities. These results suggest that compound 1 might function as a defensive compound in the capitate glandular trichomes of O. glazioviana against pathogens, insect herbivores, and presumably competitive plants as well.