Investigating the population biology of plant pathogens in their native areas is essential to understand the factors that shape their population structure and favour their spread. Monomorphic pathogens dispatch extremely low genetic diversity in invaded areas, and native areas constitute a major reservoir for future emerging strains. One of these, the gammaproteobacterium Xanthomonas citri pv. citri, causes Asiatic canker and is a considerable threat to citrus worldwide. We studied its population genetic structure by genotyping 555 strains from 12 Vietnam provinces at 14 tandem repeat loci and insertion sequences. Discriminant analysis of principal components identified six clusters. Five of them were composed of endemic strains distributed heterogeneously across sampled provinces. A sixth cluster, VN6, displayed a much lower diversity and a clonal expansion structure, suggesting recent epidemic spread. No differences in aggressiveness on citrus or resistance to bactericides were detected between VN6 and other strains. VN6 likely represents a case of bioinvasion following introduction in a native area likely through contaminated plant propagative material. Highly polymorphic markers are useful for revealing migration patterns of recently introduced populations of a monomorphic bacterial plant pathogen.

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Lobster is an aquatic species of ecological and economic importance. In Vietnam, ornate spiny lobster (Panulirus ornatus) and scallop spiny lobster (P. hormatus) are among the main species of aquaculture in Vietnam. Demand for lobster products domestically and internationally is increasing, as in the US, Japan and China markets. Today, consumers are more aware of product brands, food safety and hygiene, so product traceability is essential to protect consumers and businesses. The DNA markers are widely used for commercially traded seafood traceability. Among that, Single Nucleotide Polymorphisms (SNPs) have been shown to be robust markers, and offer high reliability. EzRAD sequencing is applied to detect potential SNPs that are characteristic for P. homarus populations in Vietnam and Sri Lanka. Through 211 valid SNPs, we detected and 12 SNPS occurring in Vietnam population, and designed 8 primer pairs to amplified 80-130 bp SNPs products. PCR optimization allows us to select 2 SNPs serving the traceability of Vietnamese P. homarus. Further need to more population sampling, and whole genome sequencing in order to develop SNPs panel to seeking the origin of lobster seafood products.

Eight secondary metabolites (1-8) were isolated from the roots of Vietnamese Eurycoma longifolia. The structures of these compounds were elucidated using a variety of spectroscopic methods. Among the compounds was eurylongilactone A (1), a new oxygenated C20 quassinoid with a 11β,20-epoxy bridge. The anti-inflammatory activities of the compounds were evaluated against LPSinduced NO production in RAW264.7 cells. Compound 1 and ethyl ferulate (8) had the strongest inhibitory effects, with IC50 values of 3.03 ± 0.73 and 3.56 ± 0.43 µM, respectively. Compounds 2, 4, and 7 had moderate activity.

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