BackgroundHerbal products available to consumers in the marketplace may be contaminated or substituted with alternative plant species and fillers that are not listed on the labels. According to the World Health Organization, the adulteration of herbal products is a threat to consumer safety. Our research aimed to investigate herbal product integrity and authenticity with the goal of protecting consumers from health risks associated with product substitution and contamination.MethodsWe used DNA barcoding to conduct a blind test of the authenticity for (i) 44 herbal products representing 12 companies and 30 different species of herbs, and (ii) 50 leaf samples collected from 42 herbal species. Our laboratory also assembled the first standard reference material (SRM) herbal barcode library from 100 herbal species of known provenance that were used to identify the unknown herbal products and leaf samples.ResultsWe recovered DNA barcodes from most herbal products (91%) and all leaf samples (100%), with 95% species resolution using a tiered approach (rbcL + ITS2). Most (59%) of the products tested contained DNA barcodes from plant species not listed on the labels. Although we were able to authenticate almost half (48%) of the products, one-third of these also contained contaminants and or fillers not listed on the label. Product substitution occurred in 30/44 of the products tested and only 2/12 companies had products without any substitution, contamination or fillers. Some of the contaminants we found pose serious health risks to consumers.ConclusionsMost of the herbal products tested were of poor quality, including considerable product substitution, contamination and use of fillers. These activities dilute the effectiveness of otherwise useful remedies, lowering the perceived value of all related products because of a lack of consumer confidence in them. We suggest that the herbal industry should embrace DNA barcoding for authenticating herbal products through testing of raw materials used in manufacturing products. The use of an SRM DNA herbal barcode library for testing bulk materials could provide a method for 'best practices? in the manufacturing of herbal products. This would provide consumers with safe, high quality herbal products.

SummaryIn Arabidopsis thaliana, a family of six genes encodes acyl-CoA-binding proteins (ACBPs) that show conservation at the acyl-CoA-binding domain. They are the membrane-associated ACBP1 and ACBP2, extracellularly targeted ACBP3, kelch-motif-containing ACBP4 and ACBP5, and 10-kDa ACBP6. The acyl-CoA domain in each of ACBP1 to ACBP6 binds long-chain acyl-CoA esters in vitro, suggestive of possible roles in plant lipid metabolism. We addressed here the use of Arabidopsis ACBPs in conferring lead [Pb(II)] tolerance in transgenic plants because the 10-kDa human ACBP has been identified as a molecular target for Pb(II) in vivo. We investigated the effect of Pb(II) stress on the expression of genes encoding Arabidopsis ACBP1, ACBP2 and ACBP6. We showed that the expression of ACBP1 and ACBP2, but not ACBP6, in root is induced by Pb(II) nitrate treatment. In vitro Pb(II)-binding assays indicated that ACBP1 binds Pb(II) comparatively better, and ACBP1 was therefore selected for further investigations. When grown on Pb(II)-containing medium, transgenic Arabidopsis lines overexpressing ACBP1 were more tolerant to Pb(II)-induced stress than the wild type. Accumulation of Pb(II) in shoots of the ACBP1-overepxressing plants was significantly higher than wild type. The acbp1 mutant showed enhanced sensitivity to Pb(II) when germinated and grown in the presence of Pb(II) nitrate and tolerance was restored upon complementation using an ACBP1 cDNA. Our results suggest that ACBP1 is involved in mediating Pb(II) tolerance in Arabidopsis with accumulation of Pb(II) in shoots. Such observations of Pb(II) accumulation, rather than Pb(II) extrusion, in the ACBP1-overexpressing plants implicate possible use of ACBP1 in Pb(II) phytoremediation.

Stress-adaptive cell plasticity in target tissues and cells for plant biomass growth is important for yield stability. In vitro systems with reproducible cell plasticity can help to identify relevant metabolic and molecular events during early cell reprogramming. In carrot, regulation of the central root meristem is a critical target for yield-determining secondary growth. Calorespirometry, a tool previously identified as promising for predictive growth phenotyping has been applied to measure the respiration rate in carrot meristem. In a carrot primary culture system (PCS), this tool allowed identifying an early peak related with structural biomass formation during lag phase of growth, around the 4th day of culture. In the present study, we report a dynamic and correlated expression of carrot AOX genes (DcAOX1 and DcAOX2a) during PCS lag phase and during exponential growth. Both genes showed an increase in transcript levels until 36 h after explant inoculation, and a subsequent down-regulation, before the initiation of exponential growth. In PCS growing at two different temperatures (21°C and 28°C), DcAOX1 was also found to be more expressed in the highest temperature. DcAOX genes’ were further explored in a plant pot experiment in response to chilling, which confirmed the early AOX transcript increase prior to the induction of a specific anti-freezing gene. Our findings point to DcAOX1 and DcAOX2a as being reasonable candidates for functional marker development related to early cell reprogramming. While the genomic sequence of DcAOX2a was previously described, we characterize here the complete genomic sequence of DcAOX1.

Epigenetic silencing is a natural phenomenon in which the expression of genes is regulated through modifications of DNA, RNA, or histone proteins. It is a mechanism for defending host genomes against the effects of transposable elements and viral infection, and acts as a modulator of expression of duplicated gene family members and as a silencer of transgenes. A major breakthrough in understanding the mechanism of epigenetic silencing was the discovery of silencing in transgenic tobacco plants due to the interaction between two homologous promoters. The molecular mechanism of epigenetic mechanism is highly complicated and it is not completely understood yet. Two different molecular routes have been proposed for this, that is, transcriptional gene silencing, which is associated with heavy methylation of promoter regions and blocks the transcription of transgenes, and post-transcriptional gene silencing (PTGS), the basic mechanism is degradation of the cytosolic mRNA of transgenes or endogenous genes. Undesired transgene silencing is of major concern in the transgenic technologies used in crop improvement. A complete understanding of this phenomenon will be very useful for transgenic applications, where silencing of specific genes is required. The current status of epigenetic silencing in transgenic technology is discussed and summarized in this mini-review.

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