No abstract

In this study, we developed a protocol for the authentication of P. vietnamensis var. vietnamensis (Ngoc Linh ginseng) by combining two molecular markers: short tandem repeat (STR) and derived cleaved ampli ed polymorphic sequences (dCAPS). STR markers: Pvm30 and Pvm31 were found in the chloroplast genome of P. vietnamensis var. vietnamensis. These markers were able to accurately identify P. stipuleanatus, P. vietnamensis var. fuscidiscus, and P. ginseng. P. vietnamensis var. vietnamensis and P. vietnamensis var. langbianensishad a high similarity of chloroplast genomic sequence (99.96%) leading to STR markers could not distinguish these two ginseng varieties. Therefore, dCAPS marker: PvmdCAPS was applied to compensate for the defect of the STR markers. From the alignment result of the matK coding sequences of these two varieties, PvmdCAPS primers were designed at the position of single nucleotide polymorphisms (SNP) at the 248th nucleotide and had the ability to discriminate between these two Panax varieties. In summary, the combination of STR and dCAPS was used to distinct Panax species in Vietnam, especially P. vietnamensis var. vietnamensis.

Species identification of Scenedesmus‐like microalgae, comprising Desmodesmus, Tetradesmus, and Scenedesmus, has been challenging due to their high morphological and genetic similarity. After developing a DNA signaturing tool for Desmodesmus identification, we built a DNA signaturing database for Tetradesmus. The DNA signaturing tool contained species‐specific nucleotide sequences of Tetradesmus species or strain groups with high similarity in ITS2 sequences. To construct DNA signaturing, we collected data on ITS2 sequences, aligned the sequences, organized the data by ITS2 sequence homology, and determined signature sequences according to hemi‐compensatory base changes (hCBC)/CBC data from previous studies. Four Tetradesmus species and 11 strain groups had DNA signatures. The signature sequence of the genus Tetradesmus, TTA GAG GCT TAA GCA AGG ACCC, recognized 86% (157/183) of the collected Tetradesmus strains. Phylogenetic analysis of Scenedesmus‐like species revealed that the Tetradesmus species were monophyletic and closely related to each other based on branch lengths. Desmodesmus was suggested to split into two subgenera due to their genetic and morphological distinction. Scenedesmus must be analyzed along with other genera of the Scenedesmaceae family to determine their genetic relationships. Importantly, DNA signaturing was integrated into a database for identifying Scenedesmus‐like species through BLAST.

In this study, we developed a protocol for the authentication of P. vietnamensis var. vietnamensis (Ngoc Linh ginseng) by combining two molecular markers: short tandem repeat (STR) and derived cleaved amplified polymorphic sequences (dCAPS). STR markers: Pvm30 and Pvm31 were found in the chloroplast genome of P. vietnamensis var. vietnamensis. These markers were able to accurately identify P. stipuleanatus, P. vietnamensis var. fuscidiscus, and P. ginseng. P. vietnamensis var. vietnamensis and P. vietnamensis var. langbianensishad a high similarity of chloroplast genomic sequence (99.96%) leading to STR markers could not distinguish these two ginseng varieties. Therefore, dCAPS marker: PvmdCAPS was applied to compensate for the defect of the STR markers. From the alignment result of the matK coding sequences of these two varieties, PvmdCAPS primers were designed at the position of single nucleotide polymorphisms (SNP) at the 248th nucleotide and had the ability to discriminate between these two Panax varieties. In summary, the combination of STR and dCAPS was used to distinct Panax species in Vietnam, especially P. vietnamensis var. vietnamensis.

Ag/SiO2 colloidal nanocomposites (NCs) were prepared through the semi-continuous chemical reduction of silver ions on a silica surface; NaBH4 was used as a primary reducing agent, while carboxymethyl cellulose (CMC) served as a secondary reductant and a stabilizer at low temperature. Silver nanoparticles (AgNPs) of an average diameter of 3.89±0.18 nm were uniformly and densely dispersed on the SiO2 surface, forming 218.6-nm-sized Ag/SiO2 NCs. The zeta potential of the Ag/SiO2 NCs (−92.6 mV) was more negative than that of silica (−24 mV), indicating their high long-term stability. Furthermore, their proposed formation mechanism was confirmed via Fourier transform infrared spectroscopy. Then, the bactericidal effect of the Ag/SiO2 was evaluated based on their minimal inhibitory concentration (MIC) against Ralstonia solanacearum 15 (R. solanacearum 15); it was 62.5 ppm, much lower than that of conventional AgNPs (500 ppm). Therefore, these highly stable Ag/SiO2 colloidal NCs with more effective antibacterial activity than conventional AgNPs are a promising nanopesticide in agriculture.