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25 June 2018, Volume 40 Issue 03
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  • Articles
    Diversity and conservation of Chinese wild begonias
    Daike Tian, Yan Xiao, Yi Tong, Naifeng Fu, Qingqing Liu, Chun Li
    2018, 40(03):  75-90.  doi:10.1016/j.pld.2018.06.002
    Abstract ( 564 )   HTML ( )   PDF (9641KB) ( 399 )   Save
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    Begonia, one of the most diverse plant taxa and the fifth or sixth largest angiosperm genus, consists of over 1800 accepted species. The number of species recognized within this genus has greatly increased over the past 20 years, rising from 80 to 200 species in China alone. Based on recent field surveys, the number of begonia species in China is predicted to be between 250 and 300. Given the large number of begonia species that still remain to be described, further taxonomical work is urgently required. This is especially true for Chinese Begonia, in which there is a huge diversity of habitat, habit, plant size, leaf type, flower and fruit morphology, and most species are narrowly distributed in isolated habitats that are subject to negative disturbances from climate change, as well as agricultural and industrial activities. Although the conservation status for the majority of species has been evaluated using the standards of the International Union for Conservation of Nature, the results don't represent the truth in many species, and also about 11.5% of which are data-absent. In addition, illegal collection and over-harvesting of wild begonias for ornamental or medicinal use has increased due to the rapid development of internet commerce. Far more often than predicted, these species should be categorized as rare and endangered and require immediate protection. Ex situ conservation of Chinese begonias started in 1995 and over 60% of the total species have been so far introduced into cultivation by several major botanical gardens in China. However, only few research institutions, limited funds and human resources have been involved in Begonia conservation; moreover, no project has conducted reintroduction. Therefore, more conservation-based work remains to be done. Improved conservation of Chinese begonias in the future depends on further field survey, an improved understanding of population diversity, and integrative approaches, including in situ and ex situ conservation, seed banking, and plant reintroduction. Speciestargeted conservation zones should be established for endangered species excluded from the existing nature reserves. Additionally, laws pertaining to plant protection should be extended to prevent the illegal collection and transaction of wild plants, particularly for those species with unique habitats and small populations.

    Securing a future for China's plant biodiversity through an integrated conservation approach
    Sergei Volis
    2018, 40(03):  91-105.  doi:10.1016/j.pld.2018.04.002
    Abstract ( 335 )   HTML ( )   PDF (1060KB) ( 196 )   Save
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    The severely threatened Chinese flora urgently needs a new, well adapted to China and properly formulated conservation strategy. The present review provides a detailed conservation methodology that complements previously described guidelines for preservation of plant species with extremely small populations (PSESP) in China. This review adds to the above concept in several aspects, making it relevant to all threatened Chinese plant species. The proposed integral conservation strategy has the following crucial components:
    -ecoregional basis for conservation planning and implementation;
    -a unified scoring system that is used in regional systematic planning for reserve design, monitoring and assessment of efficiency of a reserve network, and creation of seed banks and living collections;
    -a focus on population demography and the presence of naturally occurring regeneration as the key criteria for defining the conservation status of a species and the appropriate major focus of the species recovery plan;
    -creation of multi-species living collections that preserve species genetic variation and provide material for in situ actions;
    -experimental translocation of threatened species into multiple locations within and outside their known range.
    Adopting and implementing these strategies successfully and more fully in China requires that the country changes PA legislation and improves PA management, the National Science Foundation of China (NSFC) re-prioritizes the type of research that receives research funds, and local scientists improve their approach toward information sharing.

    A comparison of different methods for preserving plant molecular materials and the effect of degraded DNA on ddRAD sequencing
    Ying Guo, Guo-Qian Yang, Yun-Mei Chen, De-Zhu Li, Zhen-Hua Guo
    2018, 40(03):  106-116.  doi:10.1016/j.pld.2018.04.001
    Abstract ( 438 )   HTML ( )   PDF (2029KB) ( 173 )   Save
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    Obtaining high-quality plant materials for experiments is challenging for many research projects. Therefore, it is of special importance to determine the best method for preserving biological macromolecules like DNA, which degrade over time. Although some research has demonstrated that DNA degradation has little effect on traditional molecular markers, the effects of DNA degradation on ddRADseq, a popular reduced-representation sequencing technology, have not been adequately investigated. In this study, we first chose six woody bamboo species (Bambusoideae, Poaceae) to explore appropriate methods for preserving molecular materials with two DNA extraction approaches. Then we sequenced twenty-one bamboos and examined the effects of DNA quality on data generation using the ddRAD-seq technique (MiddRAD-seq). Finally, we reconstructed phylogenies of twenty woody bamboo species. We found that the integrity of dry-powdered DNA was preserved longer than that of TE-dissolved DNA, regardless of whether the DNA was extracted by a modified CTAB protocol or DNAsecure plant kit. The ddRAD-seq data were robust, except when DNA was severely degraded. In addition, we resolved the phylogenetic positions of the sampled Phyllostachys spp. Our results suggest that dry-powdered DNA is the most appropriate preservation method for plant molecular materials. Furthermore, a moderate level of DNA degradation has little effect on reduced representation sequencing techniques represented by ddRAD-seq.

    N-P fertilization did not reduce AMF abundance or diversity but alter AMF composition in an alpine grassland infested by a root hemiparasitic plant
    Xue-Zhao Wang, Xiao-Lin Sui, Yan-Yan Liu, Lei Xiang, Ting Zhang, Juan-Juan Fu, Ai-Rong Li, Pei-Zhi Yang
    2018, 40(03):  117-126.  doi:10.1016/j.pld.2018.05.001
    Abstract ( 374 )   HTML ( )   PDF (1821KB) ( 259 )   Save
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    Fertilization has been shown to have suppressive effects on arbuscular mycorrhizal fungi (AMF) and root hemiparasites separately in numerous investigations, but its effects on AMF in the presence of root hemiparasites remain untested. In view of the contrasting nutritional effects of AMF and root hemiparasites on host plants, we tested the hypothesis that fertilization may not show strong suppressive effects on AMF when a plant community was infested by abundant hemiparasitic plants. Plants and soil samples were collected from experimental field plots in Bayanbulak Grassland, where N and P fertilizers had been applied for three continuous years for control against a spreading root hemiparasite, Pedicularis kansuensis. Shoot and root biomass of each plant functional group were determined. Root AMF colonization levels, soil spore abundance, and extraradical hyphae length density were measured for three soil depths (0-10 cm, 10-20 cm, 20-30 cm). Partial 18S rRNA gene sequencing was used to detect AMF diversity and community composition. In addition, we analyzed the relationship between relative abundance of different AMF genera and environmental factors using Spearman's correlation method. In contrast to suppressive effects reported by many previous studies, fertilization showed no significant effects on AMF root colonization or AMF species diversity in the soil. Instead, a marked increase in soil spore abundance and extraradical hyphae length density were observed. However, fertilization altered relative abundance and AMF composition in the soil. Our results support the hypothesis that fertilization does not significantly influence the abundance and diversity of AMF in a plant community infested by P. kansuensis.

    Plastome characteristics of Cannabaceae
    Huan-Lei Zhang, Jian-Jun Jin, Michael J. Moore, Ting-Shuang Yi, De-Zhu Li
    2018, 40(03):  127-137.  doi:10.1016/j.pld.2018.04.003
    Abstract ( 501 )   HTML ( )   PDF (3701KB) ( 181 )   Save
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    Cannabaceae is an economically important family that includes ten genera and ca.117 accepted species. To explore the structure and size variation of their plastomes,we sequenced ten plastomes representing all ten genera of Cannabaceae.Each plastome possessed the typical angiosperm quadripartite structure and contained a total of 128 genes.The Inverted Repeat (IR) regions in five plastomes had experienced small expansions (330-983 bp) into the Large Single-Copy (LSC) region.The plastome of Chaetachme aristata has experienced a 942-bp IR contraction and lost rpl22 and rps19 in its IRs.The substitution rates of rps19 and rpl22 decreased after they shifted from the LSC to IR.A 270-bp inversion was detected in the Parasponia rugosa plastome,which might have been mediated by 18-bp inverted repeats.Repeat sequences,simple sequence repeats,and nucleotide substitution rates varied among these plastomes. Molecular markers with more than 13% variable sites and 5% parsimony-informative sites were identified,which may be useful for further phylogenetic analysis and species identification.Our results show strong support for a sister relationship between Gironniera and Lozanell (BS=100).Celtis,Cannabis-Humulus,Chaetachme-Pteroceltis,and Trema-Parasponia formed a strongly supported clade,and their relationships were well resolved with strong support (BS=100).The availability of these ten plastomes provides valuable genetic information for accurately identifying species,clarifying taxonomy and reconstructing the intergeneric phylogeny of Cannabaceae.