Bamboo tea: reduction of taxonomic complexity and application of DNA diagnostics based on rbcL and matK sequence data

Monitoring Indian "Superfood" Moringa oleifera Lam. - species-specific PCR-fingerprint-based authentication for more consumer safety

Moringa oleifera Lam. has become one of the major new superfoods commonly available in the aisles of bio-shops and health-food sections in supermarkets of North America and Europe. While most of these products appear under the generic and scientifically inconclusive term "Moringa", the European Union, so far, has allowed commercialisation for the use in food and feed for M. oleifera only. M. oleifera is indigenous to India and South Asia, but large-scale cultivation of this species has spread to the tropical regions on all continents, with a strong focus on Africa, leading to a high risk of admixture with species like M. stenopetala (Baker f.) Cufod. that is native to Africa. In the present study, we have characterised six species of Moringa in order to develop a simple and robust authentication method for commercial products. While the plants can be discriminated based on the pinnation of the leaves, this does not work for processed samples. As alternative, we use the plastidic markers psbA-trnH igs and ycf1b to discern different species of Moringa and develop a diagnostic duplex-PCR that clearly differentiates M. oleifera from other Moringa species. This DNA-based diagnostic assay that does not rely on sequencing was validated with commercial products of "Moringa" (including teas, powders, or capsules). Our method provides a robust assay to detect adulterations, which are economically profitable for costly superfood products such as "Moringa".

The Effects of Drying Techniques on Phytochemical Contents and Biological Activities on Selected Bamboo Leaves

The therapeutic potential of bamboos has acquired global attention. Nonetheless, the biological activities of the plants are rarely considered due to limited available references in Sabah, Malaysia. Furthermore, the drying technique could significantly affect the retention and degradation of nutrients in bamboos. Consequently, the current study investigated five drying methods, namely, sun, shade, microwave, oven, and freeze-drying, of the leaves of six bamboo species, Bambusa multiplex, Bambusa tuldoides, Bambusa vulgaris, Dinochloa sublaevigata, Gigantochloa levis, and Schizostachyum brachycladum. The infused bamboo leaves extracts were analysed for their total phenolic content (TPC) and total flavonoid content (TFC). The antioxidant activities of the samples were determined via the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays, whereas their toxicities were evaluated through the brine shrimp lethality assay (BSLA). The chemical constituents of the samples were determined using liquid chromatography−tandem mass spectrometry (LC-MS/MS). The freeze-drying method exhibited the highest phytochemical contents and antioxidant activity yield, excluding the B. vulgaris sample, in which the microwave-dried sample recorded the most antioxidant and phytochemical levels. The TPC and TFC results were within the 2.69 ± 0.01−12.59 ± 0.09 mg gallic acid equivalent (GAE)/g and 0.77 ± 0.01−2.12 ± 0.01 mg quercetin equivalent (QE)/g ranges, respectively. The DPPH and ABTS IC50 (half-maximal inhibitory concentration) were 2.92 ± 0.01−4.73 ± 0.02 and 1.89−0.01 to 3.47 ± 0.00 µg/mL, respectively, indicating high radical scavenging activities. The FRAP values differed significantly between the drying methods, within the 6.40 ± 0.12−36.65 ± 0.09 mg Trolox equivalent (TE)/g range. The phytochemical contents and antioxidant capacities exhibited a moderate correlation, revealing that the TPC and TFC were slightly responsible for the antioxidant activities. The toxicity assessment of the bamboo extracts in the current study demonstrated no toxicity against the BSLA based on the LC50 (lethal concentration 50) analysis at >1000 µg/mL. LC-MS analysis showed that alkaloid and pharmaceutical compounds influence antioxidant activities, as found in previous studies. The acquired information might aid in the development of bamboo leaves as functional food items, such as bamboo tea. They could also be investigated for their medicinal ingredients that can be used in the discovery of potential drugs.

A rapid, simple, and reliable assay to authenticate Peruvian kiwicha (A. caudatus) for food applications

Amaranth has acquired great economic impact as functional food, with species originating from Mexico dominating global trade. In contrast, the Peruvian A. caudatus (kiwicha) has been vastly neglected, although it is endowed with very promising nutritive traits. Morphological plasticity and taxonomic ambiguities render authentication of Amaranth difficult, such that the identity of commercial samples is often unclear. To safeguard the authenticity of kiwicha and, thus, consumer safety, we characterised a germplasm collection of 84 Amaranth accessions on both, the morphological and the genetic level. We show that kiwicha can be delineated phenotypically from other species by its late flowering, taller posture, and lower grain yields. Instead, flower and seed color, often used as proxy for identity, do not qualify as taxonomic markers. Using the plastidic barcoding marker psbA-trnH igs we were able to identify a specific Single Nucleotide Polymorphism (SNP) that separated kiwicha from all other species of Amaranth. This allowed us to develop a sequencing-free authentication assay using an Amplified Refractory Mutation System (ARMS) strategy. As a result kiwicha in commercial samples can be authenticated by a single duplex-PCR yielding a diagnostic side band reporting A. caudatus against all other species of Amaranthus. This fingerprinting assay will help to develop the nutritive potential of kiwicha and to safeguard seed material for A. caudatus against adulteration by the far more prevalent species from Mexico.

Targeted enrichment of novel chloroplast-based probes reveals a large-scale phylogeny of 412 bamboos

BACKGROUND

The subfamily Bambusoideae belongs to the grass family Poaceae and has significant roles in culture, economy, and ecology. However, the phylogenetic relationships based on large-scale chloroplast genomes (CpGenomes) were elusive. Moreover, most of the chloroplast DNA sequencing methods cannot meet the requirements of large-scale CpGenome sequencing, which greatly limits and impedes the in-depth research of plant genetics and evolution.

RESULTS

To develop a set of bamboo probes, we used 99 high-quality CpGenomes with 6 bamboo CpGenomes as representative species for the probe design, and assembled 15 M unique sequences as the final pan-chloroplast genome. A total of 180,519 probes for chloroplast DNA fragments were designed and synthesized by a novel hybridization-based targeted enrichment approach. Another 468 CpGenomes were selected as test data to verify the quality of the newly synthesized probes and the efficiency of the probes for chloroplast capture. We then successfully applied the probes to synthesize, enrich, and assemble 358 non-redundant CpGenomes of woody bamboo in China. Evaluation analysis showed the probes may be applicable to chloroplasts in Magnoliales, Pinales, Poales et al. Moreover, we reconstructed a phylogenetic tree of 412 bamboos (358 in-house and 54 published), supporting a non-monophyletic lineage of the genus Phyllostachys. Additionally, we shared our data by uploading a dataset of bamboo CpGenome into CNGB ( https://db.cngb.org/search/project/CNP0000502/ ) to enrich resources and promote the development of bamboo phylogenetics.

CONCLUSIONS

The development of the CpGenome enrichment pipeline and its performance on bamboos recommended an inexpensive, high-throughput, time-saving and efficient CpGenome sequencing strategy, which can be applied to facilitate the phylogenetics analysis of most green plants.

Microscopic Authentication of Commercial Herbal Products in the Globalized Market: Potential and Limitations

Herbal products are marketed and used around the globe for their claimed or expected health benefits, but their increasing demand has resulted in a proportionally increase of their accidental contamination or intentional adulteration, as already confirmed with DNA-based methods. Microscopy is a traditional pharmacopoeial method used for plant identification and we systematically searched for peer-reviewed publications to document its potential and limitations to authenticate herbal medicines and food supplements commercially available on the global market. The overall authenticity of 508 microscopically authenticated herbal products, sold in 13 countries, was 59%, while the rest of 41% were found to be adulterated. This problem was extending over all continents. At the national level, there were conspicuous differences, even between neighboring countries. These microscopically authenticated commercial herbal products confirm that different magnifying instruments can be used to authenticate crude or processed herbal products traded in the global marketplace. The reviewed publications report the successful use of different magnifying instruments, single or in combinations with a second one, with or without a chemical or DNA-based technique. Microscopy is therefore a rapid and cost-efficient method, and can cope with mixtures and impurities. However, it has limited applicability for highly processed samples. Microscopic authentication of commercial herbal products will therefore contribute to raise public awareness for the extent of adulteration and the need to safeguard consumer safety against the challenges of globalization.

Goji Who? Morphological and DNA Based Authentication of a "Superfood"

"Goji" (Lycium barbarum and Lycium chinense) is a generic name for medical plants with a long historical background in the traditional Chinese medicine. With the emerging trend of "Superfoods" several years ago, Goji berries soon became an established product in European countries and not only are the most popular product of traditional Chinese medicine outside of China but to this day one of the symbols of the entire "Superfood" trend. However, since Goji is an umbrella term for different plant species that are closely related, mislabeling and adulterations (unconsciously or purposely) are possible. We carefully verified the identity of Goji reference plant material based on morphological traits, mainly floral structures of several inflorescences of each individual, in order to create a robust background for the downstream applications that were used on those reference plants and additionally on commercial Goji products. We report morphological and molecular based strategies for the differentiation of Lycium barbarum and Lycium chinense. The two different Goji species vary significantly in seed size, with an almost double average seed area in Lycium chinense compared to Lycium barbarum. Differences could be traced on the molecular level as well; using the psbA-trnH barcoding marker, we detected a single nucleotide substitution that was used to develop an easy one-step differentiation tool based on ARMS (amplification refractory mutation system). Two diagnostic primers used in distinct multiplex PCRs yield a second diagnostic band in a subsequent gel electrophoresis for Lycium barbarum or Lycium chinense, respectively. Our ARMS approach is a strong but simple tool to trace either of the two different Goji species. Both the morphological and the molecular analysis showed that all of the tested commercial Goji products contained fruits of the species Lycium barbarum var. barbarum, leading to the assumption that consumer protection is satisfactory.

Product authenticity versus globalisation-The Tulsi case

Using the Indian medicinal plant Tulsi (Holy Basil) as a case study, we have tested to what extent the discrepancy between vernacular and scientific nomenclature can be resolved, whether the presumed chemical diversity underlying the medicinal use of Tulsi has a genetic component, and whether it is possible to detect this genetic component using genetic barcoding markers. Based on four plastidic markers, we can define several haplotypes within Ocimum that are consistent across these markers. Haplotype II is congruent with O. tenuiflorum, while haplotype I extends over several members of the genus and cannot be resolved into genetically separate subclades. The vernacular subdivision of Tulsi into three types (Rama, Krishna, Vana) can only be partially linked with genetic differences-whereby Rama and Krishna Tulsi can be assigned to O. tenuiflorum, while Vana Tulsi belongs to haplotype I. This genetic difference is mirrored by differences in the profiles of secondary compounds. While developmental state and light quality modulate the amplitude to which the chemical profile is expressed, the profile itself seems to be linked with genetic differences. We finally develop an authentication assay that makes use of a characteristic single nucleotide polymorphism in one of the barcoding markers, establishing a differential restriction pattern that can be used to discriminate Vana Tulsi.