Vietnam Journal of Agricultural Sciences

Magoderna subresinosum is a medicinal mushroom with potential biological activities; however, information on polysaccharides from its fruiting bodies remains limited. This study aimed to evaluate the total polysaccharide content, antioxidant activity, and anti-inflammatory potential of polysaccharide extracts from the fruiting bodies of two M. subresinosum strains, Am6 and Am32, using commercial Ganoderma lucidum strain DT as a reference. Total polysaccharide content was quantified using a D-glucose standard curve and expressed as mg GE/g dry extract. Antioxidant and anti-inflammatory activities were evaluated using the ABTS+ radical-scavenging assay and the bovine serum albumin (BSA) denaturation assay, respectively. The polysaccharide extraction yields were 11.43% and 12.23% for strains Am6 and Am32, respectively, compared with 10.24% for strain DT. Am32 showed the highest total polysaccharide content, reaching 700.08 ± 36.98 mg GE g-1 dry extract, which was significantly higher than those of strain Am6 and DT. Both M. subresinosum extracts exhibited concentration-dependent ABTS+ radical-scavenging activity, although their IC50 values were higher than those of G. lucidum strain DT and ascorbic acid. In the BSA denaturation assay, the PS extract of M. subresinosum strain Am32 exhibited the strongest anti-inflammatory activity, showing greater inhibitory activity than the PS extract of G. lucidum strain DT. These findings suggest that the fruiting bodies of M. subresinosum are an abundant source of polysaccharides with antioxidant and anti-inflammatory potential. Further studies on the composition, molecular structure, and mechanisms of action are needed to clarify the bioactive properties of polysaccharide compounds from this mushroom species.

This study investigated the potential roles of phosphoinositide-specific phospholipase C (PI-PLC) genes in cassava stress responses through promoter analysis and transcriptome-based expression profiling. Analysis of the 1kb promoter regions of seven cassava PI-PLC genes identified multiple stress- and phytohormone-responsive cis-regulatory elements, including motifs associated with drought, low temperature, defense response, abscisic acid, jasmonic acid, gibberellin, and auxin signaling. Expression analysis showed that six of the seven PI-PLC genes were differentially expressed under PEG-induced osmotic stress, with clear tissue-specific variation in roots and leaves. Under cassava brown streak disease inoculation, Manes.02G118900.1 was up-regulated 2.04-fold, whereas Manes.01G161000 and Manes.02G119100 were down-regulated 2.79-fold and 2.72-fold, respectively. These results indicate that cassava PI-PLC genes may participate in both abiotic and biotic stress-responsive regulatory networks. The findings provide useful candidates for future functional studies aimed at improving cassava tolerance to drought and viral disease.

Owing to their large size, desirable texture, and favorable flavor, Macrocybe species are considered valuable edible mushrooms with commercial cultivation potential. However, very few studies have investigated the optimal culture conditions for this genus. This study aimed to identify a wild mushroom strain, Mac-1, based on morphological characteristics and ITS sequence analysis, and to optimize culture conditions for mycelial growth and fruiting body development. Morphological observations and phylogenetic analysis indicated that strain Mac-1 belongs to the species Macrocybe gigantea. The strain exhibited the fastest mycelial growth (4.01 mm day-1) and the highest mycelial density on PGA medium at 30°C. Glucose and yeast extract were the most suitable carbon and nitrogen sources for mycelial growth, with growth rates of 3.32 and 4.43mm day-1, respectively. For mother spawn production, rice grains supplemented with 10-40% sawdust and 1% CaCO3 supported optimal mycelial colonization. The most effective cultivation substrate consisted of cotton waste and sawdust mixed at a 1:1 ratio and supplemented with 6% wheat bran. Under these conditions, rapid substrate colonization and successful fruiting body formation of strain Mac-1 were achieved, resulting in a biological efficiency of 43.05% in the first flush and an average fresh fruiting body weight of 71.78g. Overall, our findings provide a scientific basis for the cultivation of M. gigantea strain Mac-1 and demonstrate its potential as a promising edible mushroom for commercial production.

Mung bean (Vigna radiata L.) is a nutritious legume crop with significant economic value, especially in Asia. However, mung bean production can be severely affected by drought. The use of beneficial bacterial inoculants that stimulate plant growth under water-deficit conditions is a sustainable strategy for alleviating drought stress in plants. We investigated the biological characteristics and effects of drought-tolerant bacterial strain consortia on mung bean under drought conditions. Initially, three drought-tolerant bacteria, Serratia sp. L5, Bacillus sp. NG1, and Pseudomonas sp. SN1, were evaluated for their tolerance to heat, salinity, and different pH conditions. Additionally, the effects of individual and consortium inoculations on mung bean under drought conditions were evaluated through pot experiments. All three strains showed visible growth at temperatures ranging from 30 to 45°C and across a pH range of 6.0-10.0. They also maintained growth at NaCl concentrations of 3-7%, although biomass decreased to 42-67% of the control at 7% NaCl. Under water-deficit conditions, bacterial inoculation significantly promoted mung bean growth compared with the uninoculated control. Among the treatments, Serratia sp. L5, the Bacillus sp. NG1 + Pseudomonas sp. SN1 combination, and the three-strain consortium significantly improved fresh biomass, plant height, and number of leaves, with the three-strain consortium increasing fresh biomass by 67.7% compared with the control. These results indicate that the three abiotic stress-tolerant bacterial strains are promising candidates for formulation into plant growth-promoting bacterial consortia to support mung bean growth under drought conditions.

In Vietnam, the lack of elite genetic resources that combine high survival and high silk quality remains a major constraint for the development of a competitive sericulture industry. This study aimed to evaluate the biological and economic characteristics of selected silkworm breeds in order to identify promising parental lines for future hybridization programs. A total of ten silkworm breeds, including five bivoltine and five multivoltine breeds, were reared under standardized conditions. Key biological and economic traits were measured (such as survival rate, cocoon yield, cocoon shell rate, and silk filament length). The overall performance of each breed was assessed using the evaluation index (EI) method. The results revealed a clear differentiation between the two groups. The multivoltine breeds (TL, DJ, THT, 79, and VDK) exhibited higher survival rates (> 86%), indicating strong environmental adaptability. In contrast, the bivoltine breeds demonstrated higher cocoon and silk quality, with cocoon shell rates ranging from 18.20% to 21.22% and filament lengths of 590-830m. Based on the EI values, the breeds T10 (EI = 50.54), J1 (EI = 50.53), and Tan Cuu (EI = 50.32) were identified as the top-performing breeds. This study confirms that while multivoltine breeds offer better survival, bivoltine breeds are indispensable for improving silk quality. The identified breeds provide a strong genetic foundation for developing high-yielding and high-quality silkworm hybrids in Vietnam.

Bacillus mycoides and Bacillus pseudomycoides are two species within the Bacillus cereus group that share similar morphological and biochemical characteristics, making accurate identification using traditional microbiological methods difficult. This study evaluated the ability of tuf gene sequences to distinguish between these two bacterial species. Three B. mycoides strains and two B. pseudomycoides strains were examined for morphological and biochemical characteristics and subjected to 16S rRNA and tuf gene sequencing. Analyses included the five study strains together with GenBank reference datasets comprising 94 16S rRNA sequences (45 B. mycoides and 49 B. pseudomycoides) and 92 tuf sequences (49 B. mycoides and 43 B. pseudomycoides) to evaluate within- and between-species sequence similarity. The results showed that all the study strains exhibited rhizoid colony morphology and similar biochemical characteristics, which did not allow differentiation between the two species. Analysis of 16S rRNA gene sequences revealed a very high level of similarity between B. mycoides and B. pseudomycoides, reaching up to 100%, and therefore was not sufficient to distinguish the two species. In contrast, tuf gene sequences clearly distinguished the two species, with within-species similarity ranging from 98.2 to 100% and interspecies similarity ranging from 96.0 to 96.8%. Phylogenetic analysis further resolved all isolates into two distinct species-specific clades. These findings indicate that the tuf gene showed greater discriminatory power than the 16S rRNA gene for differentiating B. mycoides and B. pseudomycoides among the strains and reference sequences analysed in this study.

Streptomyces species are renowned for their capacity to produce diverse bioactive secondary metabolites and remain an important source of novel natural products. We performed an integrated genome-based characterization of Streptomyces sp. YIM 121038 using whole-genome phylogeny, genome similarity analyses, functional annotation, and biosynthetic gene cluster (BGC) prediction. Genome-scale analysis showed that YIM 121038 possesses a typical high-GC (72.86%) and gene-rich genome (10.13 Mbp, 9,312 coding sequences), together with a large 967.9-kb linear plasmid representing the largest accessory replicon among the analyzed strains. Whole-genome phylogenomic reconstruction using TYGS clustered YIM 121038 within the S. spectabilis lineage, a finding consistently supported by OrthoANI and digital DNA–DNA hybridization (dDDH) analyses. YIM 121038 exhibited the highest genomic similarity to S. spectabilis NRRL 2792 (92.25% OrthoANI; 67.8% dDDH) and S. spectabilis ATCC 27465 (92.16% OrthoANI; 65.8% dDDH), while remaining below the accepted species delineation thresholds. Genome mining with antiSMASH identified 45 putative biosynthetic gene clusters on the chromosome and nine on the linear plasmid, including numerous NRPS-, type I PKS-, terpene-, RiPP-, and hybrid-associated clusters, indicating substantial biosynthetic diversity. Consistently, KEGG functional annotation revealed a broad representation of genes involved in secondary metabolism and core metabolic pathways. The agreement among phylogenomic, genome similarity, and functional analyses demonstrates that YIM 121038 possesses a characteristic Streptomyces genome architecture together with extensive potential for specialized metabolite biosynthesis. These findings provide a comprehensive genomic framework for understanding the evolutionary position and biosynthetic potential of YIM 121038 and support future experimental investigation of its specialized metabolites.

Rehmannia glutinosa (Gaertn.) Libosch. ex DC. is an important medicinal plant whose tuberous roots are widely used as pharmaceutical and herbal raw materials. This study aimed to establish an efficient in vitro propagation and tuberous root induction protocol for R. glutinosa by evaluating the effects of benzyladenine, α-naphthaleneacetic acid, indole-3-acetic acid, coconut water, sucrose concentration, and photoperiod. Shoot tips of 2-3cm length with 3-4 leaf pairs were cultured on Murashige and Skoog (MS) medium under controlled in vitro conditions. The best shoot multiplication response was obtained on MS medium supplemented with 1.0 mg L-1 benzyladenine and 150 mL L-1 coconut water, producing 4.93 shoots explant-1 after four weeks of culture. For root induction, MS medium containing 1.0 mg L-1 indole-3-acetic acid gave the highest rooting performance, with 100% rooting, 34.06 roots plantlet-1, and a root length of 3.75cm after four weeks. In vitro tuberous root formation was optimal on MS medium supplemented with 0.3 mg L-1 α-naphthaleneacetic acid and 70 g L-1 sucrose, producing 4.72 tuberous roots plantlet-1 and 0.116 g plantlet-1 fresh weight after six weeks. Among the tested photoperiods, 12 h light/12 h dark gave the best tuberous root development, with 4.31 tuberous roots plantlet-1 and 0.097 g plantlet-1 fresh weight. These results provide a practical protocol for rapid multiplication, rooting, and tuberous root induction of R. glutinosa, supporting the production of uniform and disease-free planting materials for medicinal plant cultivation.