Plant secondary metabolites play critical roles in plant-environment interactions. They are synthesized in different organs or tissues at particular developmental stages, and in response to various environmental stimuli, both biotic and abiotic. Accordingly, corresponding genes are regulated at the transcriptional level by multiple transcription factors. Several families of transcription factors have been identified to participate in controlling the biosynthesis and accumulation of secondary metabolites. These regulators integrate internal (often developmental) and external signals, bind to corresponding cis-elements -which are often in the promoter regions -to activate or repress the expression of enzyme-coding genes, and some of them interact with other transcription factors to form a complex. In this review, we summarize recent research in these areas, with an emphasis on newly-identified transcription factors and their functions in metabolism regulation.

With the rapid development of nanotechnologies, nanoparticles (NPs) are increasingly produced and used in many commercial products, which could lead to the contact of human blood vessels with NPs. Thus, it is necessary to understand the adverse effects of NPs to relevant cells lining human blood vessels, especially endothelial cells (ECs) that cover the lumen of blood vessels. Human umbilical vein endothelial cells (HUVECs) are among one of the most popular models used for ECs in vitro. In the present review, we discussed studies that have used HUVECs as a model to investigate the EC-NP interactions, the toxic effects of NPs on ECs and the mechanisms. The results of these studies indicated that NPs could be internalized into HUVECs by the endocytosis pathway as well as transported across HUVECs by exocytosis and paracellular pathways. Exposure of HUVECs to NPs could induce cytotoxicity, genotoxicity, eNOS uncoupling and endothelial activation, which could be explained by NP-induced oxidative stress, inflammatory response and dysfunction of organelles. In addition, some studies have also evaluated the influences of microenvironment (e.g. the presence of proteins and excessive nutrients), the physiological and/or pathological stimuli related to the diversity of ECs (e.g. shear stress, cyclic stretch and inflammatory stimuli), and the physicochemical properties of NPs on the responses of ECs to NP exposure. In conclusion, it has been suggested that HUVECs could be considered as a relatively reliable and simple in vitro model for ECs to predict and evaluate the toxicity of NPs to endothelium. Copyright © 2017 John Wiley & Sons, Ltd.

Immunity deteriorates with age in animals but comparatively little is known about the temporal regulation of plant resistance to herbivores. The phytohormone jasmonate (JA) is a key regulator of plant insect defense. Here, we show that the JA response decays progressively in Arabidopsis. We show that this decay is regulated by the miR156-targeted SQUAMOSA PROMOTER BINDING PROTEIN-LIKE9 (SPL9) group of proteins, which can interact with JA ZIM-domain (JAZ) proteins, including JAZ3. As SPL9 levels gradually increase, JAZ3 accumulates and the JA response is attenuated. We provide evidence that this pathway contributes to insect resistance in young plants. Interestingly however, despite the decay in JA response, older plants are still comparatively more resistant to both the lepidopteran generalist Helicoverpa armigera and the specialist Plutella xylostella, along with increased accumulation of glucosinolates. We propose a model whereby constitutive accumulation of defense compounds plays a role in compensating for age-related JA-response attenuation during plant maturation.