Mating in flowering plants normally relies on animals, wind, gravity or secretion to convey pollen grains from the male (anther) to the female (stigma) organ. Here we describe a new type of self-pollination mechanism in the tree-living orchid Holcoglossum amesianum, in which the bisexual flower turns its anther against gravity through 360 degrees in order to insert pollen into its own stigma cavity - without the aid of any pollinating agent or medium. This mode of self-pollination, which occurs under windless, drought conditions when insects are scarce, adds to the variety of mechanisms that have evolved in angiosperms to ensure their reproductive success.

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Orchid pollination and evolution are common topics in evolutionary biology. China has approximately 1400 orchid species distributed in diverse habitats and account for approximately 5% of the orchid species in the world. These orchids provide us with materials to explore coevolution and organic evolution. We summarized 53 Chinese orchid pollination studies and synthesized their main findings and common patterns. Bees and flies are the main pollinators of Chinese orchids and drive the diversification of Paphiopedilum and Cypripedium. In addition, the patterns are consistent with phylogenetic evolution studies. Almost half of the Chinese orchids use a common fooddeceptive pollination strategy to transfer their pollens. Other orchids use Batesian mimicry, brood-site imitation, and green-leaf volatile imitation, which is rare. Holcoglossum amesianum (Rchb. f.) Christenson and Paphiopedilum parishii (Rchb. f.) Stein, which live in insect-scarce habitats, use self-pollination strategies to ensure their reproductive success. However, studies on pollination are in the early stages and comprehensive studies are scarce. Therefore, future studies should involve additional disciplines and techniques, such as chemecologic, electrophysiologic, genomic, transcriptomic, and proteomic methods, to evaluate the floral features that attract specific pollinators and to elucidate the patterns of Chinese orchid pollination, evolutionary history, diversification, and speciation between orchids and their pollinators.

Hoya is a remarkable genus with high horticultural ornamental value. In this study, we report and characterize the complete plastid genome sequence of Hoya carnosa. The complete chloroplast genome was 176,340 bp in length, which includes a pair of inverted repeat regions (IRs) of 41,381 bp separated by a large single copy region (LSC) 91,281 bp and a small single copy region (SSC) 2,297 bp. Interestingly, IRs expanded into SSC, with the result that most of the genes in SSC were duplicated. This chloroplast genome contained 110 genes, including 76 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. The complete plastome sequence of H. carnosa will provide some useful information for future phylogenetic study of Hoya and its horticultural application.

Eucalyptus is harvested for wood and fiber production in many tropical and sub-tropical habitats globally. Plantation has been controversial because of its influence on the surrounding environment, however, the influence of massive Eucalyptus planting on soil microbial communities is unclear. Here we applied high-throughput sequencing of the 16S rRNA gene to assess the microbial community composition and diversity of planting chronosequences, involving two, five and ten years of Eucalyptus plantation, comparing to that of secondary-forest in South China. We found that significant changes in the composition of soil bacteria occurred when the forests were converted from secondary-forest to Eucalyptus. The bacterial community structure was clearly distinct from control and five year samples after Eucalyptus was grown for 2 and 10 years, highlighting the influence of this plantation on local soil microbial communities. These groupings indicated a cycle of impact (2 and 10 year plantations) and low impact (5-year plantations) in this chronosequence of Eucalyptus plantation. Community patterns were underpinned by shifts in soil properties such as pH and phosphorus concentration. Concurrently, key soil taxonomic groups such as Actinobacteria showed abundance shifts, increasing in impacted plantations and decreasing in low impacted samples. Shifts in taxonomy were reflected in a shift in metabolic potential, including pathways for nutrient cycles such as carbon fixation, which changed in abundance over time following Eucalyptus plantation. Combined these results confirm that Eucalyptus plantation can change the community structure and diversity of soil microorganisms with strong implications for land-management and maintaining the health of these ecosystems.