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Dai S.,CAS South China Botanical Garden | Dai S.,University of Chinese Academy of Sciences | Dai S.,Guangzhou Institute of Landscape Gardening | Wu W.,CAS South China Botanical Garden | And 5 more authors.
Biochemical Systematics and Ecology | Year: 2012

In this study, we sequenced two nuclear genes and one chloroplast spacer in Melastoma intermedium, a shrub species endemic to China, and its putative parental species, Melastoma candidum and Melastoma dodecandrum, to test the hybrid-origin hypothesis. Our results revealed that in one nuclear gene there were five fixed nucleotide substitutions between M. candidum and M. dodecandrum, and in the other nuclear gene, there were six. All but one individual of M. intermedium showed additivity in chromatograms at these sites of at least one gene. Haplotypes of M. candidum and M. dodecandrum at the two nuclear genes were well separated, and most haplotypes of M. intermedium were shared with those of M. candidum and M. dodecandrum. M. candidum and M. dodecandrum differed by three nucleotide substitutions in the chloroplast spacer, whereas individuals of M. intermedium had identical sequences to either M. candidum or M. dodecandrum. The molecular data clearly demonstrate that M. intermedium is of hybrid origin. © 2011 Elsevier Ltd. Source


Liu T.,Sun Yat Sen University | Chen Y.,Sun Yat Sen University | Chao L.,Sun Yat Sen University | Wang S.,Sun Yat Sen University | And 5 more authors.
PLoS ONE | Year: 2014

Natural hybridization can lead to various evolutionary outcomes in plants, including hybrid speciation and interspecific gene transfer. It can also cause taxonomic problems, especially in plant genera containing multiple species. In this study, the hybrid status of Melastoma affine, the most widespread taxon in this genus, and introgression between its putative parental species, M. candidum and M. sanguineum, were assessed on two sites, Hainan and Guangdong, using 13 SSR markers and sequences of a chloroplast intergenic spacer. Bayesian-based STRUCTURE analysis detected two most likely distinct clusters for the three taxa, and 76.0% and 73.9% of the morphologically identified individuals of M. candidum and M. sanguineum were correctly assigned, respectively. 74.5% of the M. affine individuals had a membership coefficient to either parental species between 0.1 and 0.9, suggesting admixture between M. candidum and M. sanguineum. Furthermore, NewHybrids analysis suggested that most individuals of M. affine were F2 hybrids or backcross hybrids to M. candidum, and that there was extensive introgression between M. candidum and M. sanguineum. These SSR data thus provides convincing evidence for hybrid origin of M. affine and extensive introgression between M. candidum and M. sanguineum. Chloroplast DNA results were consistent with this conclusion. Much higher hybrid frequency on the more disturbed Guangdong site suggests that human disturbance might offer suitable habitats for the survival of hybrids, a hypothesis that is in need of further testing. © 2014 Liu et al. Source


Li J.,University of Macau | Zhang J.,Guangzhou Institute of Landscape Gardening | Lu Y.,South China Agricultural University | Chen Y.,University of Macau | And 2 more authors.
Environmental Monitoring and Assessment | Year: 2012

The total petroleum hydrocarbons (TPH) pollution in regional agricultural soils was investigated. Seventy soil samples collected from surface layers (0-20 cm) and horizons of five selected pedons in the vicinity of a petrochemical complex in Guangzhou, China were analyzed, and the vertical variation and spatial variability of TPH were evaluated. The TPH concentration in top soils around the petrochemical complex ranged from 1,179.3 to 6,354.9 mg kg- 1, with the average of 2,676.6 mg kg- 1. Furthermore, significant differences between land-use types showed that the TPH concentration in top soils was strongly influenced by accidental spills. Both the TPH trends in pedons and the identified hot-spot areas also showed that the accidental explosions or burning accidents were mainly responsible for the pollution. The results reported here suggest that the regular monitoring and inspection shall be conducted for safety and to avoid or minimize the accidents, and the effective measures should be taken to remediate the contaminated areas and to assure that the important industrialization of Guangzhou area would not mean human health risks near the petrochemical complex. © 2011 Springer Science+Business Media B.V. Source


Xin G.,Sun Yat Sen University | Ye S.,Sun Yat Sen University | Ye S.,Guangzhou Institute of Landscape Gardening | Wu E.,Inner Mongolia Agricultural University | And 2 more authors.
Pakistan Journal of Botany | Year: 2012

The seasonal dynamics in the colonization of the rhizosphere of orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.) pastures by arbuscular mycorrhizal (AM) fungi and the production of spores in an artifical Japanese grassland was investigated over 12 months (between December 2001 and December 2002). The results showed that the AM fungal colonization fluctuated seasonally in the rhizosphere of both pastures. The total AM fungal colonization of the two pastures decreased during winter, then increased from March to June as the pastures grew, but slightly decreased again in July and August, and again followed an increase in September. There was significant difference of the colonization by arbuscules and vesicles between the two pastures (p<0.05). Besides, the vesicular colonization of orchardgrass was higher than that of white clover, but the opposite trend was observed for arbuscular colonization. Similarly, the numbers of AM fungal spores in the pastures varied throughout the year, decreasing from spring to summer, then slowly increasing in late summer, reaching peak levels in winter. There is significant correlation between the frequency of spores in the rhizosphere soil and both soil temperature and pH. Source


Hu Y.-Q.,South China Agricultural University | Su Z.-Y.,South China Agricultural University | Ke X.-D.,South China Agricultural University | Xiong Y.-M.,Guangzhou Institute of Landscape Gardening
Journal of Food, Agriculture and Environment | Year: 2013

The importance of eucalypt plantations to industrial forestry has been widely recognised. However, growing concern about the effects of eucalypt plantations on the environment has given rise to disputes in plantation forestry. In this study, using understory vegetation as environmental indicators, we compared species composition, diversity, and community structure of two eucalypt plantations (one-year-old and three-year-old eucalypt plantations) with the indigenous flora, with an aim to gain new insights into the environmental effects of eucalypt plantation. The two eucalypt plantations were significantly lower in species richness and number of individuals in the understory as compared with the indigenous flora. All the diversity measures except species-specific density (number of individuals per species) were different between the eucalypt and the indigenous forest stands. The dominance/diversity curves of the two eucalypt stands had similar shapes, which were together far apart from that of the indigenous forest stand. Correlation analysis of ordination sample scores indicated that the two eucalypt stands was positively related, while they were negatively correlated to the indigenous forest stand. Most of the indicator species of the two eucalypt stands were ruderal herbs and shrubs, while the indicator species for the indigenous forest understory were dominant tree seedlings, shrubs and lianas. However, all the understory species in different stands were native species from the local species pool. No invasive plant species had been found to occur in the understory of the eucalypt plantations. Our study suggested that environmental impacts of eucalypt plantations on local biodiversity existed, however, fears about eucalypt trees as "big killers of local species" and eucalypt plantations as "green desert" should be reconsidered. Source

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