Polygonum minus Huds. is a medicinal aromatic plant rich in terpenes, aldehydes, and phenolic compounds. Methyl jasmonate (MeJA) is a plant signaling molecule commonly applied to elicit stress responses to produce plant secondary metabolites. In this study, the effects of exogenous MeJA treatment on the composition of volatile organic compounds (VOCs) in P. minus leaves were investigated by using a metabolomic approach. Time-course changes in the leaf composition of VOCs on days 1, 3, and 5 after MeJA treatment were analyzed through solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). The VOCs found in MeJA-elicited leaves were similar to those found in mock-treated leaves but varied in quantity at different time points. We focused our analysis on the content and composition of monoterpenes, sesquiterpenes, and green leaf volatiles (GLVs) within the leaf samples. Our results suggest that MeJA enhances the activity of biosynthetic pathways for aldehydes and terpenes in P. minus. Hence, the production of aromatic compounds in this medicinal herb can be increased by MeJA elicitation. Furthermore, the relationship between MeJA elicitation and terpene biosynthesis in P. minus was shown through SPME-GC-MS analysis of VOCs combined with transcriptomic analysis of MeJA-elicited P. minus leaves from our previous study.
The natural rubber of Para rubber tree, Hevea brasiliensis, is the main crop involved in industrial rubber production due to its superior quality. The Hevea bark is commercially exploited to obtain latex, which is produced from the articulated secondary laticifer. The laticifer is well defined in the aspect of morphology; however, only some genes associated with its development have been reported. We successfully induced secondary laticifer in the jasmonic acid (JA)-treated and linolenic acid (LA)-treated Hevea bark but secondary laticifer is not observed in the ethephon (ET)-treated and untreated Hevea bark. In this study, we analysed 27,195 gene models using NimbleGen microarrays based on the Hevea draft genome. 491 filtered differentially expressed (FDE) transcripts that are common to both JA- and LA-treated bark samples but not ET-treated bark samples were identified. In the Eukaryotic Orthologous Group (KOG) analysis, 491 FDE transcripts belong to different functional categories that reflect the diverse processes and pathways involved in laticifer differentiation. In the Kyoto Encyclopedia of Genes and Genomes (KEGG) and KOG analysis, the profile of the FDE transcripts suggest that JA- and LA-treated bark samples have a sufficient molecular basis for secondary laticifer differentiation, especially regarding secondary metabolites metabolism. FDE genes in this category are from the cytochrome (CYP) P450 family, ATP-binding cassette (ABC) transporter family, short-chain dehydrogenase/reductase (SDR) family, or cinnamyl alcohol dehydrogenase (CAD) family. The data includes many genes involved in cell division, cell wall synthesis, and cell differentiation. The most abundant transcript in FDE list was SDR65C, reflecting its importance in laticifer differentiation. Using the Basic Local Alignment Search Tool (BLAST) as part of annotation and functional prediction, several characterised as well as uncharacterized transcription factors and genes were found in the dataset. Hence, the further characterization of these genes is necessary to unveil their role in laticifer differentiation. This study provides a platform for the further characterization and identification of the key genes involved in secondary laticifer differentiation.
Fragaria chiloensis fruit has a short postharvest life mainly due to its rapid softening. In order to improve its postharvest life, preharvest applications of methyl jasmonate (MeJA) and chitosan were evaluated during postharvest storage at room temperature. The quality and chemical parameters, and protection against decay were evaluated at 0, 24, 48 and 72 h of storage from fruits of two subsequent picks (termed as first harvest and second harvest). In general, fruits treated with MeJA and chitosan maintained higher levels of fruit firmness, anthocyanin, and showed significant delays in decay incidence compared to control fruit. MeJA-treated fruits exhibited a greater lignin content and SSC/TA ratio, and delayed decay incidences. Instead, chitosan-treated fruits presented higher antioxidant capacity and total phenol content. In short, both the elicitors were able to increase the shelf life of fruits as evidenced by the increased levels of lignin and anthocyanin, especially of the second harvest.
The importance of plant secondary metabolites for both mankind and the plant itself has long been established. However, despite extensive research on plant secondary metabolites, plant secondary metabolism and its regulation still remained poorly characterized. In this present study, cDNA-amplified fragment length polymorphism (cDNA-AFLP) transcript profiling was applied to generate the expression profiles of Polygonum minus in response to salicylic acid (SA) and methyl jasmonate (MeJA) elicitations. This study reveals two different sets of genes induced by SA and MeJA, respectively where stress-related genes were proved to lead to the expression of genes involved in plant secondary metabolite biosynthetic pathways. A total of 98 transcript-derived fragments (TDFs) were up-regulated, including 46 from SA-treated and 52 from MeJA-treated samples. The cDNA-AFLP transcripts generated using 64 different Mse1/Taq1 primer combinations showed that treatments with SA and MeJA induced genes mostly involved in scavenging reactive oxygen species, including zeaxanthin epoxidase, cytosolic ascorbate peroxidase 1 and peroxidase. Of these stress-related genes, 15 % of other annotated TDFs are involved mainly in secondary metabolic processes where among these, two genes encoding (+)-delta cadinene synthase and cinnamoyl-CoA reductase were highlighted.
Melastoma malabathricum, belongs to the Melastomaceae family, is an important medicinal plant widely distributed from Madagascar to Australia, that is used in traditional remedies for the treatment of various ailments. Besides its medicinal properties, it has been identified as a potential source of anthocyanin production. The present study was carried out to investigate the effect of sucrose and methyl jasmonate and feeding time on cell biomass yield and anthocyanin production in cell suspension culture of M. malabathricum. Addition of different concentrations of sucrose into the cell culture of M. malabathricum influenced cell biomass and pigment accumulation. The addition of methyl jasmonate was found to have no effect on cell biomass but the presence of higher amount (12.5-50 mg/L) had caused a reduction in anthocyanin production and accumulation. MS medium supplemented with 30 g/L sucrose and 3.5 mg/L of MeJA added on cero day and 3rd day produced high fresh cell mass at the end of nine days of culture but did not support the production of anthocyanins. However, cells cultured in the medium supplemented with 45 g/L sucrose without MeJA showed the highest pigment content (0.69 +/- 0.22 CV/g-FCM). The cells cultured in MS medium supplemented with 30 g/L sucrose with 3.5 mg/L MeJA added on the 3rd and 6th day of culture, showed the lowest pigment content (0.37-0.40 CV/g-FCM). This study indicated that MeJA was not necessary but sucrose was needed for the enhancement of cell growth and anthocyanin production in M. malabathricum cell cultures.
Since 2003, highly pathogenic A(H5N1) influenza viruses have been the cause of large-scale death in poultry and the subsequent infection and death of over 140 humans. A group of 55 influenza A(H5N1) viruses isolated from various regions of South East Asia between 2004 and 2006 were tested for their susceptibility to the anti-influenza drugs the neuraminidase inhibitors and adamantanes. The majority of strains were found to be fully sensitive to the neuraminidase inhibitors oseltamivir carboxylate, zanamivir and peramivir; however two strains demonstrated increased IC50 values. Sequence analysis of these strains revealed mutations in the normally highly conserved residues 116 and 117 of the N1 neuraminidase. Sequence analysis of the M2 gene showed that all of the A(H5N1) viruses from Vietnam, Malaysia and Cambodia contained mutations (L26I and S31N) associated with resistance to the adamantane drugs (rimantadine and amantadine), while strains from Indonesia were found to be a mix of both adamantane resistant (S31N) and sensitive viruses. None of the A(H5N1) viruses from Myanmar contained mutations known to confer adamantane resistance. These results support the use of neuraminidase inhibitors as the most appropriate class of antiviral drug to prevent or treat human A(H5N1) virus infections.