Phylogenetic studies of magnoliids: Advances and perspectives

Magnoliids are the largest flowering plant clades outside of the eudicots and monocots, which are distributed worldwide and have high economic, ornamental and ecological values. Eudicots, monocots and magnoliids are the three major clades of Mesangiospermae, and their phylogenetic relationship is one of the most interesting issues. In recent years, with the continuous accumulation of genomic information, the evolutionary status of magnoliids has become a hot spot in plant phylogenetic research. Although great efforts have been made to study the evolution of magnoliids using molecular data from several representative species such as nuclear genome, plastid genome, mitochondrial genome, and transcriptome, the results of current studies on the phylogenetic status of magnoliids are inconsistent. Here, we systematically describe the current understanding of the molecular research on magnoliid phylogeny and review the differences in the evolutionary state of magnoliids. Understanding the research approaches and limitations of magnoliid phylogeny can guide research strategies to further improve the study of the phylogenetic evolution of magnoliids

Seabuckthorn Paste Protects Lipopolysaccharide-Induced Acute Lung Injury in Mice through Attenuation of Oxidative Stress

Oxidative stress is one of the major mechanisms implicated in endotoxin-induced acute lung injury. Seabuckthorn paste (SP), a traditional Tibetan medicine with high content of polyphenols and remarkable antioxidant activity, is commonly used in treating pulmonary diseases. In the present study, the protective effects and possible underlying mechanisms of SP on lipopolysaccharide- (LPS-) induced acute lung injury in mice were investigated. It was found that body weight loss, lung tissue microstructure lesions, transvascular leakage increase, malondialdehyde augmentation, and the reduction of superoxide dismutase and glutathione peroxidase levels caused by LPS challenge were all consistently relieved by SP treatment in a dose-dependent manner. Moreover, accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) in lung nuclei caused by SP treatment was observed. Our study demonstrated that SP can provide significant protection against LPS-induced acute lung injury through maintaining redox homeostasis, and its mechanism involves Nrf2 nuclear translocation and activation

Distinct double flower varieties in Camellia japonica exhibit both expansion and contraction of C-class gene expression

Double flower domestication is of great value in ornamental plants and presents an excellent system to study the mechanism of morphological alterations by human selection. The classic ABC model provides a genetic framework underlying the control of floral organ identity and organogenesis from which key regulators have been identified and evaluated in many plant species. Recent molecular studies have underscored the importance of C-class homeotic genes, whose functional attenuation contributed to the floral diversity in various species. Cultivated Camellia japonica L. possesses several types of double flowers, however the molecular mechanism underlying their floral morphological diversification remains unclear. In this study, we cloned the C-class orthologous gene CjAG in C. japonica. We analyzed the expression patterns of CjAG in wild C. japonica, and performed ectopic expression in Arabidopsis. These results revealed that CjAG shared conserved C-class function that controls stamen and carpel development. Further we analyzed the expression pattern of CjAG in two different C. japonica double-flower varieties, `Shibaxueshi’ and `Jinpanlizhi’, and showed that expression of CjAG was highly contracted in `Shibaxueshi’ but expanded in inner petals of `Jinpanlizhi’. Moreover, detailed expression analyses of B- and C-class genes have uncovered differential patterns of B-class genes in the inner organs of `Jinpanlizhi’. These results demonstrated that the contraction and expansion of CjAG expression were associated with the formation of different types of double flowers. Our studies have manifested two different trajectories of double flower domestication regarding the C-class gene expression in C. japonica.https://doi.org/10.1186/s12870-014-0288-

Integrating GC-MS and comparative transcriptome analysis reveals that TsERF66 promotes the biosynthesis of caryophyllene in Toona sinensis tender leaves

IntroductionThe strong aromatic characteristics of the tender leaves of Toona sinensis determine their quality and economic value.Methods and resultsHere, GC-MS analysis revealed that caryophyllene is a key volatile compound in the tender leaves of two different T. sinensis varieties, however, the transcriptional mechanisms controlling its gene expression are unknown. Comparative transcriptome analysis revealed significant enrichment of terpenoid synthesis pathway genes, suggesting that the regulation of terpenoid synthesis-related gene expression is an important factor leading to differences in aroma between the two varieties. Further analysis of expression levels and genetic evolution revealed that TsTPS18 is a caryophyllene synthase, which was confirmed by transient overexpression in T. sinensis and Nicotiana benthamiana leaves. Furthermore, we screened an AP2/ERF transcriptional factor ERF-IX member, TsERF66, for the potential regulation of caryophyllene synthesis. The TsERF66 had a similar expression trend to that of TsTPS18 and was highly expressed in high-aroma varieties and tender leaves. Exogenous spraying of MeJA also induced the expression of TsERF66 and TsTPS18 and promoted the biosynthesis of caryophyllene. Transient overexpression of TsERF66 in T. sinensis significantly promoted TsTPS18 expression and caryophyllene biosynthesis.DiscussionOur results showed that TsERF66 promoted the expression of TsTPS18 and the biosynthesis of caryophyllene in T. sinensis leaves, providing a strategy for improving the aroma of tender leaves

Tissue-specific transcriptomics reveals a central role of CcNST1 in regulating the fruit lignification pattern in Camellia chekiangoleosa, a woody oil-crop

Fruit lignification is of significant economic importance because it affects the quality of fruit and the production of seed oil. The specified lignification pattern in Camellia chekiangoleosa fruits plays critical roles in its seed oil yield, but little is known about how this lignification process is regulated. Here, we report on a comprehensive tissue-specific transcriptomics analysis conducted for C. chekiangoleosa fruit. By mining the differentially expressed genes, we found that lignin biosynthesis and transcriptional regulation pathways were significantly enriched in the lignified tissues. The homolog of NST-like transcription factor, CcNST1, was highly expressed in lignified seed coat and endocarp tissues; transgenic analyses of CcNST1 in Arabidopsis and hybrid poplar revealed the enhanced lignification levels of various tissues. Gene expression analysis of the transgenic lines uncovered potential downstream genes involved in the regulation of lignin biosynthesis. This work provides a valuable gene expression resource and identified the pivotal role of CcNST1 in regulating the lignin biosynthesis underlying fruit lignification

The Kalanchoe genome provides insights into convergent evolution and building blocks of crassulacean acid metabolism

Crassulacean acid metabolism (CAM) is a water-use efficient adaptation of photosynthesis that has evolved independently many times in diverse lineages of flowering plants. We hypothesize that convergent evolution of protein sequence and temporal gene expression underpins the independent emergences of CAM from C3 photosynthesis. To test this hypothesis, we generate a de novo genome assembly and genome-wide transcript expression data for Kalanchoë fedtschenkoi, an obligate CAM species within the core eudicots with a relatively small genome (~260 Mb). Our comparative analyses identify signatures of convergence in protein sequence and re-scheduling of diel transcript expression of genes involved in nocturnal CO2 fixation, stomatal movement, heat tolerance, circadian clock, and carbohydrate metabolism in K. fedtschenkoi and other CAM species in comparison with non-CAM species. These findings provide new insights into molecular convergence and building blocks of CAM and will facilitate CAM-into-C3 photosynthesis engineering to enhance water-use efficiency in crops

Plant biosystems design research roadmap 1.0

Human life intimately depends on plants for food, biomaterials, health, energy, and a sustainable environment. Various plants have been genetically improved mostly through breeding, along with limited modification via genetic engineering, yet they are still not able to meet the ever-increasing needs, in terms of both quantity and quality, resulting from the rapid increase in world population and expected standards of living. A step change that may address these challenges would be to expand the potential of plants using biosystems design approaches. This represents a shift in plant science research from relatively simple trial-and-error approaches to innovative strategies based on predictive models of biological systems. Plant biosystems design seeks to accelerate plant genetic improvement using genome editing and genetic circuit engineering or create novel plant systems through de novo synthesis of plant genomes. From this perspective, we present a comprehensive roadmap of plant biosystems design covering theories, principles, and technical methods, along with potential applications in basic and applied plant biology research. We highlight current challenges, future opportunities, and research priorities, along with a framework for international collaboration, towards rapid advancement of this emerging interdisciplinary area of research. Finally, we discuss the importance of social responsibility in utilizing plant biosystems design and suggest strategies for improving public perception, trust, and acceptance