[Excellent appearance of Dao-di Ginseng Radix et Rhizoma and interaction mechanism between genetic and environmental factors: a review].

Dao-di medicinal materials produced in a specific environment always present excellent appearance and high quality. Because of the unique appearance, Ginseng Radix et Rhizoma is regarded as a paradigm in the research on excellent appearance. This paper systematically summarized the research progress in the genetic and environmental factors influencing the formation of the excellent appearance of Ginseng Radix et Rhizoma, aiming to provide reference for the quality improvement of Ginseng Radix et Rhizoma and the scientific connotation of Dao-di Chinese medicinal materials. The Ginseng Radix et Rhizoma with high quality generally has a robust and long rhizome, a large angle between branch roots, and the simultaneous presence of a robust basal part of rhizome, adventitious roots, rhizome bark with circular wrinkles, and fibrous roots with pearl points. The cultivated and wild Ginseng Radix et Rhizoma have significant differences in the appearance and no significant difference in the population genetic diversity. The differences in the appearance are associated with cell wall modification, transcriptional regulation of genes involved in plant hormone transduction, DNA methylation, and miRNA regulation. The rhizosphere soil microorganisms including Fusarium and Alternaria, as well as the endophytes Trichoderma hamatum and Nectria haematococca, may be the key microorganisms affecting the growth and development of Panax ginseng. Cultivation mode, variety, and root exudates may be the main factors influencing the stability of rhizosphere microbial community. Ginsenosides may be involved in the formation of the excellent appearance. However, most of the available studies focus on the partial or single factors in the formation of Dao-di medicinal materials, ignoring the relationship within the complex ecosystems, which limits the research on the formation mechanism of Dao-di medicinal materials. In the future, the experimental models for the research involving genetic and environmental factors should be established and mutant materials should be developed to clarify the internal relationship between factors and provide scientific support for the research on Dao-di medicinal materials.

[Effect of BBM gene on callus growth and ginsenoside content in Panax quinquefolius].

Baby Boom(BBM) gene is a key regulatory factor in embryonic development and regeneration, cell proliferation, callus growth, and differentiation promotion. Since the genetic transformation system of Panax quinquefolius is unstable with low efficiency and long period, this study attempted to transfer BBM gene of Zea mays to P. quinquefolius callus by gene gunship to investigate its effect on the callus growth and ginsenoside content, laying a foundation for establishing efficient genetic transformation system of P. quinquefolius. Four transgenic callus of P. quinquefolius with different transformation events were obtained by screening for glufosinate ammonium resistance and molecular identification by PCR. The growth state and growth rate of wild-type and transgenic callus were compared in the same growth period. The content of ginsenoside in transgenic callus was determined by ultra-high performance liquid chromatography-triple quadrupole mass spectrometry(UPLC-MS/MS). The results showed that transgenic callus growth rate was significantly higher than that of wild-type callus. In addition, the content of ginsenoside Rb_1, Rg_1, Ro, and Re was significantly higher than that in wild-type callus. The paper preliminarily proved the function of BBM gene in promoting growth rate and increasing ginsenoside content, which provided a scientific basis to establish a stable and efficient genetic transformation system for Panax plants in the future.

Genome-wide analysis of Panax MADS-box genes reveals role of PgMADS41 and PgMADS44 in modulation of root development and ginsenoside synthesis.

Panax root is an important material used in food and medicine. Its cultivation and production usually depend on root shape and ginsenoside content. There is limited understanding about the synergistic regulatory mechanisms underlying root development and ginsenoside accumulation in Panax. MADS-box transcription factors possibly play a significant role in regulation of root growth and secondary metabolites. In this study, we identified MADS-box transcription factors of Panax, and found high expression levels of SVP, ANR1 and SOC1-like clade genes in its roots. We confirmed that two SOC1-like genes, PgMADS41 and PgMADS44, bind to expansion gene promoters (PgEXLB5 and PgEXPA13), which contribute to root growth, and to SE-4, CYP716A52v2-4, and ß-AS-13 promoters, which participate in ginsenoside Ro biosynthesis. These two genes were found to increase lateral root number and main root length in transgenic Arabidopsis thaliana by improving AtEXLA1, AtEXLA3, AtEXPA5, and AtEXPA6 gene expression. As a non-phytohormone regulatory tool, Ro can stimulate adventitious root growth by influencing their expression and ginsenoside accumulation. Our study provides new insights into the coordinated regulatory function of SOC1-like clade genes in Panax root development and triterpenoid accumulation, paving the way towards understanding root formation and genetic improvement in Panax.

[Bioinformatics analysis and function prediction of ginseng TCP transcription factor family].

The longevity mechanism of ginseng(Panax ginseng) is related to its strong meristematic ability. In this paper, this study used bioinformatic methods to identify the members of the ginseng TCP gene family in the whole genome and analyzed their sequence characteristics. Then, quantitative real-time fluorescent PCR was performed to analyze the TCP genes containing elements rela-ted to meristem expression in the taproots, fibrous roots, stems, and leaves. According to the data, this study further explored the expression specificity of TCP genes in ginseng tissues, which facilitated the dissection of the longevity mechanism of ginseng. The ginseng TCP members were identified and analyzed using PlantTFDB, ExPASy, MEME, PLANTCARE, TBtools, MEGA and DNAMAN. The results demonstrated that there were 60 TCP gene family members in ginseng, and they could be divided into two classes: Class Ⅰ and Class Ⅱ, in which the Class Ⅱ possessed two subclasses: CYC-TCP and CIN-TCP. The deduced TCP proteins in ginseng had the length of 128-793 aa, the isoelectric point of 4.49-9.84 and the relative molecular mass of 14.2-89.3 kDa. They all contained the basic helix-loop-helix(bHLH) domain. There are a variety of stress response-related cis-acting elements in the promoter regions of ginseng TCP genes, and PgTCP20-PgTCP24 contained the elements associated with meristematic expression. The transcription levels of PgTCP20-PgTCP24 were high in fibrous roots and leaves, but low in stems, indicating the tissue-specific expression of ginseng TCP genes. The Class Ⅰ TCP members which contained PgTCP20-PgTCP23, may be important regulators for the growth and development of ginseng roots.

Development of a concentration method for detection of tobacco mosaic virus in irrigation water.

Tobacco mosaic virus (TMV) causes significant yield loss in susceptible crops irrigated with contaminated water. However, detection of TMV in water is difficult owing to extremely low concentrations of the virus. Here, we developed a simple method for the detection and quantification of TMV in irrigation water. TMV was reliably detected at concentrations as low as 10 viral copies/µL with real-time PCR. The sensitivity of detection was further improved using polyethylene glycol 6000 (PEG6000, MW 6000) to concentrate TMV from water samples. Among the 28 samples from Shaanxi Province examined with our method, 17 were tested positive after virus concentration. Infectivity of TMV in the original water sample as well as after concentration was confirmed using PCR. The limiting concentration of TMV in water to re-infect plants was determined as 10(2) viral copies/mL. The method developed in this study offers a novel approach to detect TMV in irrigation water, and may provide an effective tool to control crop infection.