The complete chloroplast genome of Dicliptera tinctoria (Nees) Kostel. and comparative analysis of chloroplast genomes in Acanthaceae.

Dicliptera tinctoria is a member of Acanthaceae, which has a wide distribution and contains potentially medicinal species, and exhibited pharmaceutical potentials. This study sequenced and characterized the complete chloroplast genome of Dicliptera tinctoria. The newly sequenced cpDNA of D. tinctoria was 150,733 bp in length and had a typical quadripartite structure consisting of a large single copy (LSC, 82,895 bp), a small single copy (SSC, 17,249 bp), and two inverted repeat (IRs, 25,295 bp each) regions. This genome also contained 80 protein-coding genes, 30 transfer RNAs, and four ribosomal RNAs, which is identical to other chloroplast genomes in Acanthaceae family. Nucleotides diversity analysis among chloroplast genomes of Acanthaceae species revealed eight hypervariable regions, including trnK_UUU-matK, trnC_GCA-petN, accD, rps12-clpP, rps3-rps19, ycf1-ndhF, ccsA-ndhD, and ycf1. Phylogenetic analysis revealed the paraphyly of Dicliptera species and monophyly in four Acanthaceae subfamilies. These results provide an overview of genomic variations in Acanthaceae chloroplast genome, which is helpful for further genomic studies.

Metabolic and genomic analysis deciphering biocontrol potential of endophytic Streptomyces albus RC2 against crop pathogenic fungi.

Plant diseases caused by phytopathogenic fungi are one of the leading factors affecting crop loss. In the present study, sixty-one Streptomyces strains were screened for their antifungal activity against relevant wide range fungal pathogens prominent in Vietnam, namely Lasiodiplodia theobromae, Fusarium fujikuroi, and Scopulariopsis gossypii. Endophytic strain RC2 was the most effective strain in the mycelial inhibition of the tested fungi. Based on phenotypic characteristics, 16S rDNA gene analysis, and genomic analysis, strain RC2 belonged to Streptomyces albus. An ethyl acetate extract of S. albus RC2 led to the strong growth inhibition of S. gossypii Co1 and F. fujikuroi L3, but not L. theobromae N13. The crude extract also suppressed the spore germination of S. gossypii Co1 and F. fujikuroi L3 to 92.4 ± 3.2% and 87.4% ± 1.9%, respectively. In addition, the RC2 extract displayed potent and broad-spectrum antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and the phytopathogenic bacteria Ralstonia solanacearum and Xanthomonas oryzae. The genome of strain RC2 was sequenced and revealed the presence of 15 biosynthetic gene clusters (BGCs) with similarities ≥ 45% to reference BGCs available in the antiSMASH database. The UPLC-HRMS analysis led to the identification of 8 other secondary metabolites, which have not been reported in S. albus. The present study indicated that RC2 could be a potent biocontrol agent against phytopathogenic fungi. Further attention should be paid to antifungal metabolites without functional annotation, development of product prototypes, and greenhouse experiments to demonstrate effective control of the plant diseases.

Investigation on the in vitro antioxidant capacity of methanol extract, fractions and flavones from Oroxylum indicum Linn bark

ABSTRACT Antioxidants from natural sources hold high values regarding their indispensible roles in the development of nutraceuticals, pharmaceuticals and cosmetic products. Oroxylum indicum L. is a common medicinal plant with a wide range of therapeutic properties, including a notable antioxidant potency that was reported, yet has not been subjected to more detailed studies. The present study evaluated the potency of Oroxylum indicum methanol stem bark extract, along with its hexane, ethyl acetate, methanol fractions, three flavones including baicalein, oroxylin A and chrysin using DPPH assay. In terms of IC50 values, the crude extract (65,48 µg/mL) exhibited moderate inhibitory activity which was as half potent as that of its ethyl acetate fraction (32,94 µg/mL). This fraction was also superior to the methanol and hexane fractions, as their IC50 were 57,19 and 137,95 µg/mL respectively. Remarkably, a yellow powdery sub-fraction consisted of isolated compounds showed powerful activity (32,89 µg/mL) compared to those of its components, revealing the intriguing effect of synergism while giving evidence for the theory of structure-activity relationship between some flavones and their antioxidant capability. Perpetual search for new radical scavenging agents in Oroxylum indicum is emboldened considering its partially exploited potential in this study