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Ginkgolides and bilobalide, collectively termed terpene trilactones (TTLs), are terpenoids that form the main active substance of Ginkgo biloba. Terpenoids in the mevalonate (MVA) biosynthetic pathway include acetyl-CoA C-acetyltransferase (AACT) and mevalonate kinase (MVK) as core enzymes. In this study, two full-length (cDNAs) encoding AACT (GbAACT, GenBank Accession No. KX904942) and MVK (GbMVK, GenBank Accession No. KX904944) were cloned from G. biloba. The deduced GbAACT and GbMVK proteins contain 404 and 396 amino acids with the corresponding open-reading frame (ORF) sizes of 1215 bp and 1194 bp, respectively. Tissue expression pattern analysis revealed that GbAACT was highly expressed in ginkgo fruits and leaves, and GbMVK was highly expressed in leaves and roots. The functional complementation of GbAACT in AACT-deficient Saccharomyces cerevisiae strain Δerg10 and GbMVK in MVK-deficient strain Δerg12 confirmed that GbAACT mediated the conversion of mevalonate acetyl-CoA to acetoacetyl-CoA and GbMVK mediated the conversion of mevalonate to mevalonate phosphate. This observation indicated that GbAACT and GbMVK are functional genes in the cytosolic mevalonate (MVA) biosynthesis pathway. After G. biloba seedlings were treated with methyl jasmonate and salicylic acid, the expression levels of GbAACT and GbMVK increased, and TTL production was enhanced. The cloning, characterization, expression and functional analysis of GbAACT and GbMVK will be helpful to understand more about the role of these two genes involved in TTL biosynthesis.

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Selenium is an essential trace element which plays an important role in human immune regulation and disease prevention. Plants absorb inorganic selenium (selenite or selenate) from the soil and convert it into various organic selenides (such as seleno amino acids, selenoproteins, and volatile selenides) via the sulfur metabolic pathway. These organic selenides are important sources of dietary selenium supplementation for humans. Organoselenides can promote plant growth, improve nutritional quality, and play an important regulatory function in plant ecosystems. The release of selenium-containing compounds into the soil by Se hyperaccumulators can promote the growth of Se accumulators but inhibit the growth and distribution of non-Se accumulators. Volatile selenides with specific odors have a deterrent effect on herbivores, reducing their feeding on plants. Soil microorganisms can effectively promote the uptake and transformation of selenium in plants, and organic selenides in plants can improve the tolerance of plants to pathogenic bacteria. Although selenium is not an essential trace element for plants, the right amount of selenium has important physiological and ecological benefits for them. This review summarizes recent research related to the functions of selenium in plant ecosystems to provide a deeper understanding of the significance of this element in plant physiology and ecosystems and to serve as a theoretical basis and technical support for the full exploitation and rational application of the ecological functions of selenium-accumulating plants.

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Selenium (Se) is an essential trace element for humans and animals, and it plays an important role in immune regulation and disease prevention. Tea is one of the top three beverages in the world, and it contains active ingredients such as polyphenols, theanine, flavonoids, and volatile substances, which have important health benefits. The tea tree has suitable Se aggregation ability, which can absorb inorganic Se and transform it into safe and effective organic Se through absorption by the human body, thereby improving human immunity and preventing the occurrence of many diseases. Recent studies have proven that 50~100.0 mg/L exogenous Se can promote photosynthesis and absorption of mineral elements in tea trees and increase their biomass. The content of total Se and organic selenides in tea leaves significantly increases and promotes the accumulation of polyphenols, theanine, flavonoids, and volatile secondary metabolites, thereby improving the nutritional quality of tea leaves. This paper summarizes previous research on the effects of exogenous Se treatment on the growth and quality of tea trees to provide a theoretical basis and technical support for the germplasm selection and exploitation of Se-rich tea.

Roman chamomile (Chamaemelum nobile L.) is renowned for its production of essential oils, which major components are sesquiterpenoids. As the important enzyme in the sesquiterpenoid biosynthesis pathway, 3-hydroxy-3-methylglutaryl coenzyme A synthase (HMGS) catalyze the crucial step in the mevalonate pathway in plants. To isolate and identify the functional genes involved in the sesquiterpene biosynthesis of C. nobile L., a HMGS gene designated as CnHMGS (GenBank Accession No. KU529969) was cloned from C. nobile. The cDNA sequence of CnHMGS contained a 1377 bp open reading frame encoding a 458-amino-acid protein. The sequence of the CnHMGS protein was highly homologous to those of HMGS proteins from other plant species. Phylogenetic tree analysis revealed that CnHMGS clustered with the HMGS of Asteraceae in the dicotyledon clade. Further functional complementation of CnHMGS in the mutant yeast strain YSC6274 lacking HMGS activity demonstrated that the cloned CnHMGS cDNA encodes a functional HMGS. Transcript profile analysis indicated that CnHMGS was preferentially expressed in flowers and roots of C. nobile. The expression of CnHMGS could be upregulated by exogenous elicitors, including methyl jasmonate and salicylic acid, suggesting that CnHMGS was elicitor-responsive. The characterization and expression analysis of CnHMGS is helpful to understand the biosynthesis of sesquiterpenoid in C. nobile at the molecular level and also provides molecular wealth for the biotechnological improvement of this important medicinal plant.

ObjectiveThis study aimed to describe preliminary experiences associated with removal of tracheobronchial foreign bodies (TFBs) by cystourethroscopy (CU).MethodsWe performed a retrospective analysis of 127 paediatric cases of TFB removal by CU at our centre from January 2009 to August 2016. Data that were extracted from the medical records included age, sex, location and nature of the TFBs, operation time, and complications.ResultsAll TFBs were successfully removed by CU. The mean time of the procedure was 3.38 ± 2.86 minutes. A total of 102 (80.31%) patients had successful removal of TFBs by CU during the initial trial, 19 (14.96%) were successfully treated in the second trial, and six (4.72%) required a third trial. Otolaryngologists with 2, 5, and 7 years of professional CU training showed a mean TFB removal time of 3.38 ± 2.13, 3.40 ± 3.60, and 3.37 ± 2.86 minutes, respectively. In the operations, oxygen saturation fell below 90% at an average occurrence of 0.39 times, but no patients showed a decrease below 85%. Only one patient experienced laryngeal oedema after the procedure.ConclusionCU is a useful technique and minimizes complications and operational risks during removal of paediatric TFBs.