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Cassiicolin (Cas), a toxin produced by Corynespora cassiicola, is responsible for Corynespora leaf fall disease in susceptible rubber trees. Currently, the molecular mechanisms of the cytotoxicity of Cas and its host selectivity have not been fully elucidated. Here, we analyzed the binding of Cas1 and Cas2 to membranes consisting of different plant lipids and their membrane disruption activities. Using high-speed atomic force microscopy and confocal microscopy, we reveal that the binding and disruption activities of Cas1 and Cas2 on lipid membranes are strongly dependent on the specific plant lipids. The negative phospholipids, glycerolipids, and sterols are more sensitive to membrane damage caused by Cas1 and Cas2 than neutral phospholipids and betaine lipids. Mature Cas1 and Cas2 play an essential role in causing membrane disruption. Cytotoxicity tests on rubber leaves of Rubber Research Institute of Vietnam (RRIV) 1, RRIV 4, and Prang Besar (PB) 255 clones suggest that the toxins cause necrosis of rubber leaves, except for the strong resistance of PB 255 against Cas2. Cryogenic scanning electron microscopy analyses of necrotic leaf tissues treated with Cas1 confirm that cytoplasmic membranes are vulnerable to the toxin. Thus, the host selectivity of Cas toxin is attained by the lipid-dependent binding activity of Cas to the membrane, and the cytotoxicity of Cas arises from its ability to form biofilm-like structures and to disrupt specific membranes.

β-Indole acetic acid is produced in the rhizosphere by endophytic bacteria and promotes plant growth. Effects of bacterial IAA producers (BIPs) on plant growth and recovery of sugarcane seedlings infected with phytoplasma causing white leaf disease (SWLD) were examined. Fifty-five endophytic bacteria isolated from rice roots were collected from the Mekong River Delta, Vietnam. Seven isolates showed β-Indole acetic acid production in culture medium supplemented with tryptophan. Interestingly, two of them (BC17 and BTII2) produced the highest β-Indole acetic acid after 4 days of culture. Based on 16S rRNA sequences and phylogenetic analysis, the BC17 and BTII2 isolates were identified as Delftia lacustris and Rahnella aquatilis, respectively. Plant growth induced by the BC17 and BTII2 isolates showed statistically significant differences in height, root length and fresh weight of rice seedlings compared with non-treatment as the control. Treatment of two bacterial isolates in SWLD infected sugarcane plants also showed differences in height of sugarcane seedlings, while gradual symptoms of exposure decreased plant mortality compared to non-treatment as the control. BIPs were shown to be efficient biofertilizer inoculants that promoted plant growth and also ameliorated damage caused by phytoplasma-associated diseases at the sugarcane seedling stage.

Magnaporthe oryzae is the causal agent of rice blast disease resulting in yield losses in rice-growing regions worldwide, particularly in Vietnam. Up-regulation of osa-miR7695 was observed in blast resistant rice cultivars in comparison with blast non-resistant rice cultivars. The OsNramp6 gene is a target for osa-miR7695, and considered a factor involved in rice immunity but scant evidence has demonstrated systematic expression profiles of OsNramp6 transcript variants involving M. oryzae susceptibility and resistance of rice plants. In this study, a real-time qPCR (qRT-PCR) approach was used to evaluate the expression levels of eight OsNramp6 transcript variants in various Vietnamese rice cultivars. Results indicated that OsNramp6.1 and OsNramp6.4 transcript variants showed decreased expression levels at 24 hpi in M. oryzae resistant rice cultivars and vice versa in the rice group of M. oryzae resistance, suggesting that both could be used as potential markers for discrimination between blast resistant and non-resistant Vietnamese rice cultivars. Identification of potential microRNAs in rice that contribute to the regulation of OsNramp6 transcripts-mediated facilitation of infection by M. oryzae has still to be confirmed for elucidating their roles in rice immunity against M. oryzae.

Coconut (Cocos nucifera L.) production sustains millions of smallholder farmers and their families around the globe, and also powers a thriving industry of climate-adaptive nutrition and biomaterials. Demand for high-quality planting materials has risen sharply in recent years, calling for greater understanding and potential utilization of the genetic diversity in coconut populations. Genetic diversity among several conserved coconut varieties in Vietnam was investigated to assess the suitability of 15 start codon targeted (SCoT) primers for future selective breeding programs. Amplification of 15 SCoT primers in 57 individuals from 19 coconut varieties revealed high intra-varietal diversity (Nei’s genetic diversity index = 0.237, Shannon’s Information index = 0.352), especially among the Vietnamese Dwarfs. Intriguingly, inter-varietal differentiation accounted for only 9.41% of total genetic variation. The designated SCoT primers were moderately informative. On average, each primer had 9.5 reproducible polymorphic bands per reaction. Polymorphism Information Content (PIC) per locus ranged between 0.217 and 0.390, with Resolving power (Rp) between 0.271 and 0.599. Principal Coordinate Analysis (PCoA) and Unweighted Pair Group Method with Arithmetic mean (UPGMA) analyses revealed distinct clusters for non-native Dwarf, native Dwarf, and Tall varieties. This paper represents the first-of-its-kind attempt to shed light on coconut genetic diversity in Vietnam using molecular markers.

We investigated the influence of convenient diets on big-eyed bug Geocoris ochropterus. Development and reproduction of G. ochropterus fed on convenient diets of ant pupae Oecophylla smaragdina and silkworm pupae Bombyx mori were examined using aphids Aphis gossypii as the control diet. Results showed that Geocoris ochropterus nymphs completed development to adults on all diets. Total average development period was 35.1 days fed on ant pupae, 35.9 days fed on silkworm pupae, and 36.0 days fed on aphids. Head width, body length, forewing length, and fresh body weight of adults were not affected by diets, except for females reared on ant pupae that were significantly heavier than those fed on aphids. There was no significant difference in offspring sex ratio. Total number of eggs deposited per female fed on ant pupae was significantly larger than when fed on aphids, while eggs laid by females fed on silkworm pupae were significantly longer than eggs laid by females fed on aphids. Results suggest that ant pupae and silkworm pupae could be effectively used for mass rearing of G. ochropterus.

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and the third cause of cancer-related death worldwide. Potential microRNAs have been reported as biomarkers for early detection of HCC as well as novel molecular targets for HCC treatment. Various tissue expression profiles of miRNAs using three microarray datasets from groups in Asia (2), Europe, America (GSE147892, GSE21362, GSE74618, GSE40744) and multiple bioinformatics tools were integrated to determine the most significant miRNA groups to assist in the diagnosis of HCC. Statistical analyses identified at least 30 miRNAs with 17 up-regulated and 13 down-regulated in HCC-related tumor tissues. All the miRNAs also showed relevance to the hallmarks of cancer such as cell proliferation, invasion, metastasis, angiogenesis, metabolism, epithelial-mesenchymal transition and apoptosis. Expression levels of miRNAs observed in the European group showed up-regulation at 5-37% compared to both Asian and American groups. Interestingly, four miRNAs divided into two groups as miR-182-5p/miR-1269a and miR-199a/miR-422a were the most promising for diagnosis of HCC patients from healthy controls, with AUC values of 0.902 and 0.892, respectively. Results provided evidence of the correlation between potential miRNAs and HCC that could be useful for disease diagnosis based on in-depth analyses of large case numbers and cohort studies.

Magnaporthe oryzae causes rice blast disease, which leads to devastating yield losses in Vietnam and other rice-growing countries. Recent studies indicated that 30% of rice- growing areas are affected by rice blast disease. MicroRNAs (miRNAs) are short non-coding RNAs that are related to plant development and biotic stress tolerance. Osa-miR7695 as one of the common miRNAs, and its target the OsNramp6 gene were evaluated as factors that contribute to the pathogenic activity of different rice cultivars. The expression profile of microRNA osa-miR7695 was evaluated to identify blast resistance or susceptibility in rice cultivars. Results of RT-PCR and real-time qPCR indicated the presence of osa-miR7695 in most Oryzae sativa Indica group cultivars in Vietnam. Upregulation of osa-miR7695 observed in blast resistant rice cultivars at different infection time intervals was higher than in blast non-resistant rice cultivars. Expression of the OsNramp6 gene increased in blast non-resistant cultivars, particularly at 72 h post inoculation. Average ΔCt values of osa-miR7695 in blast resistant rice cultivars were higher by approximately 4-fold than in blast non-resistant rice cultivars. Results suggested osa-miR7695 as a potential biomarker for microRNA based detection of blast resistance and non-resistance in Vietnamese rice cultivars to improve understanding of the biological role of microRNA in rice immunity.

Phloem-limiting phytoplasmas are known to be causal agents of phyllody, which is recognized by the abnormal development of floral structures resulting in serious yield losses in sesame plants. Currently, identification of the various groups of phytoplasmas that cause sesame phyllody (SP) is conducted by nested PCR, RFLP, and multiplex real-time qPCR assays. However, these methods require intensive labor and are costly and time-consuming so can only be undertaken in well-equipped labs. Here, diagnostic loop-mediated isothermal amplification (LAMP)–based assays allowing rapid detection of specific groups of phytoplasmas within 30 min were developed based on detection of the 16S rRNA sequence of phytoplasmas. Universal 16S rRNA phytoplasma primers and seven primer sets of different 16Sr group phytoplasmas (16SrI, 16SrII, 16SrIII, 16SrIV, 16SrV, 16SrX, 16SrXI) and universal plant cytochrome oxidase (cox) gene primers were used to detect 16S rRNA group phytoplasma sequences and the cox gene in sesame plants. The LAMP assays were carried out using a real-time fluorometer with amplification plots and annealing curves visualized directly. Results demonstrated that the 16SrI and 16SrII group phytoplasmas were causal agents of sesame phyllody in Vietnam. LAMP-based assays for in-field detection of sesame phyllody-causing phytoplasmas revealed advantages and potential applicability in comparison with conventional approaches. To the best of our knowledge, this is the first assessment of multiple phytoplasma infection associated with sesame phyllody disease in Vietnam using LAMP-based assays.

PCR-based molecular approaches including RAPD (random amplified polymorphic DNA), ISSR (inter-simple sequence repeat), and SRAP (sequence-related amplified polymorphism) are commonly used to analyze genetic diversity. The aims of this study are to analyze genetic diversity of M. oryzae isolates using PCR-based molecular approaches such as RAPD, ISSR, and SRAP and to develop SCAR marker linked to the pathogenicity of rice blast fungus. Twenty Magnaporthe oryzae isolates were collected mainly from the south of Vietnam and assessed for genetic variation by RAPD, ISSR, and SRAP methods. The comparison of those methods was conducted based on the number of polymorphic bands, percentage of polymorphism, PIC values, and phylogenetic analysis. Then, sequenced characterized amplified region (SCAR) markers were developed based on specific bands linked to fungal pathogenicity of rice blast fungus, M. oryzae. The results indicated that SRAP markers yielded the greatest number of polymorphic bands (174) and occupied 51.7% with polymorphism information content (PIC) value of 0.66. Additionally, the SRAP approach showed stability and high productivity compared with RAPD and ISSR. The SCAR marker developed from the SRAP method identified the presence of the avirulence AVR-pita1 gene involving fungal pathogenicity that can break down blast resistance in rice cultivars. The consistency of SCAR marker obtained in this study showed its efficiency in rapid in-field detection of fungal pathogenicity. SCAR marker developed from SRAP technique provides a useful tool for improving the efficiency of blast disease management in rice fields.

In this study, 25 endophytic bacteria were isolated and purified from rhizome, stem and leaf of the elephant grass, which were tested for their biological control properties. The number of living and dead brown plant hoppers were recorded and the mortality rate was analyzed by using Abbott’s formula. The results indicated that three endophytic bacteria including VBL1, VBT1 and VBT5 showed the highest biological control of Nilaparvata lugens at the mortality rate 46.95%, 55.02% and 55.02%, respectively after 8 days of screening and significant difference compared to other isolates (P

BACKGROUND Hepatocellular carcinoma (HCC) is the leading cause of cancer-related death in the world and considered as one of the most susceptible cancers in humans. The microRNA molecule, hsa-miR122, considered as a potential biological marker linked with the injury of hepatocellular tissue, is the most common microRNA in human liver cancer. Understanding the expression profile of hsa-miR122 plays an important role in the diagnosis of HCC. OBJECTIVE Identification and comparison of cut-off values of plasma hsa-miR122 expression were conducted in blood samples of healthy control, HBV infected and HBV-related HCC Vietnamese patients. METHODS AND RESULT Fifty-two blood samples of healthy control and HBV-related HCC cases, collected between 2015 and 2017 were obtained from Ho Chi Minh City Oncology Hospital, Vietnam. Written informed consent was attained from all patients and the Human Research Ethics Committee, Oncology Hospital (#08/BVUB-HDDD) approved the research protocol. Total RNA was isolated from blood samples with TrizolTM Reagent (Thermo Fisher Scientific, USA). To analyze the expression level of hsa-miR122, miRNA specific reverse transcription was performed using Sensi- FASTTM cDNA Synthesis Kit (Bioline, UK) as described by the manufacturer, followed by running RT-qPCR with SensiFASTTMSYBR No-ROX Kit (Bioline, UK). The housekeeping gene, GAPDH (glyceraldehyde-3-phosphate dehydrogenase) was used for normalization. The presence of hsamiR122 and HBV-DNA was identified in human blood using RT-PCR and LAMP techniques. Downregulation of plasma hsa-miR122 was observed in HBV-related HCC patients with a .Ct value of 7.9 ± 2.1 which was significantly lower than found in healthy control (p

Sugarcane white leaf disease (SWLD) and grassy shoot disease (SGSD) are caused by phytoplasma transmission between plants through insect vectors and infected cane setts, resulting in severe reduction of global yield and quality. Vietnam has large areas of sugarcane cultivation, and huge losses are caused by SWLD and SGSD, which impact on the sugar industry and local farmers. The current situation is summarized, and strategies to control white leaf and grassy shoot phytoplasma-associated sugarcane diseases in Vietnam are presented.

Recently, many studies have demonstrated the significant advantages of loop-mediated isothermal amplification (LAMP) based methods over serological tests and PCR for rapid detection of microbial pathogens. Here, a rapid LAMP assay was developed to detect the hepatitis B virus (HBV) from DNA, and particularly, blood samples from infected patients using a commercially available master mix and portable real-time fluorometer. The final optimized fluorescence-based LAMP assay provided significant amplification time of less than 15 minutes compared with over 1 hour for PCR and an opened tube LAMP system described previously. Results indicated that fluorescence-based LAMP assay was more sensitive than PCR as a rapid, sensitive, efficient, and highly reliable approach for rapid detection of HBV.

In the post-genomics era, RNAi has rapidly become a powerful reverse genetic tool for elucidating gene function in a wide range of eukaryotes including fungi. In this review, we focus on recent discoveries of RNAi-related biological phenomena in fungi and their underlying molecular mechanisms. In addition, recent advances in RNA-mediated gene silencing technologies and their potential use for functional genomics studies in fungi are discussed.