The fruits of Canarium tramdenum are commonly used as foods and cooking ingredients in Vietnam, Laos, and the southeast region of China, whilst the leaves are traditionally used for treating diarrhea and rheumatism. This study was conducted to investigate the potential use of this plant bark as antioxidants, and α-amylase and α-glucosidase inhibitors. Five different extracts of C. tramdenum bark (TDB) consisting of the extract (TDBS) and factional extracts hexane (TDBH), ethyl acetate (TDBE), butanol (TDBB), and water (TDBW) were evaluated. The TDBS extract contained the highest amount of total phenolic (112.14 mg gallic acid equivalent per g dry weight), while the TDBB extract had the most effective antioxidant capacity compared to other extracts. Its IC50 values were 12.33, 47.87, 33.25, and 103.74 µg/mL in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (ABTS), reducing power (RP), and nitric oxide (NO) assays, respectively. Meanwhile, the lipid peroxidation inhibition of the four above extracts was proximate to that of butylated hydroxytoluene (BHT) as a standard antioxidant. The result of porcine pancreatic α-amylase inhibition showed that TDB extracts have promising effects which are in line with the commercial diabetic inhibitor acarbose. Interestingly, the inhibitory ability on α-glucosidase of all the extracts was higher than that of acarbose. Among the extracts, the TDBB extract expressed the strongest activity on the enzymatic reaction (IC50 = 18.93 µg/mL) followed by the TDBW extract (IC50 = 25.27 µg/mL), TDBS (IC50 = 28.17 µg/mL), and TDBE extract (IC50 = 141.37 µg/mL). The phytochemical constituents of the TDB extract were identified by gas chromatography–mass spectrometry (GC-MS). The principal constituents included nine phenolics, eight terpenoids, two steroids, and five compounds belonging to other chemical classes, which were the first reported in this plant. Among them, the presence of α- and β-amyrins were identified by GC-MS and appeared as the most dominant constituents in TDB extracts (1.52 mg/g). The results of this study revealed that C. tramdenum bark possessed rich phenolics and terpenoids, which might confer on reducing risks from diabetes. A high quantity of α- and β-amyrins highlighted the potentials of anti-inflammatory, anti-ulcer, anti-hyperlipidemic, anti-tumor, and hepatoprotective properties of C. tramdenum bark.

Salinity stress is one of the most problematic constraints to significantly reduce rice productivity. The Saltol QTL (quantitative trait locus) has been known as one among many principal genes/QTLs responsible for salinity tolerance in rice. However, the introgression of the Saltol QTL from the donor (male) into the recipient (female) cultivars induces great recessions from the progeny generation, which results in heavy fieldwork and greater cost and time required for breeding. In this study, the F1 generation of the cross TBR1 (female cultivar, salinity tolerant) × KD18 (male cultivar, salinity susceptible) was preliminarily treated with N-methyl-N-nitrosourea (MNU) to induce the mutants M1. Results on physiological traits show that all the M2 (self-pollinated from M1) and M3 (self-pollinated from M2) individuals obtain salinity tolerant levels as the recurrent TBR1. Twelve SSR (simple sequence repeat) markers involved in the Saltol QTL (RM493, RM562, RM10694, RM10720, RM10793, RM10852, RM13197, RM201, RM149, RM508, RM587, and RM589) and other markers related to yield-contributing traits and disease resistance, as well as water and nitrogen use, have efficacy that is polymorphic. The phenotype and genotype analyses indicate that the salinity tolerant Saltol QTL, growth parameter, grain yield and quality, pest resistance, water and nitrogen use efficacy, and beneficial phytochemicals including antioxidants, momilactone A (MA) and momilactone B (MB) are uniparentally inherited from the recurrent (female) TBR1 cultivar and stabilized in the M2 and M3 generations. Further MNU applications should be examined to induce the uniparental inheritance of other salinity tolerant genes such as OsCPK17, OsRMC, OsNHX1, OsHKT1;5 to target rice cultivars. However, the mechanism of inducing this novel uniparental inheritance for salinity tolerance by MNU application needs elaboration.

Next generation sequencing technologies have provided numerous opportunities for application in the study of whole plant genomes. In this study, we present the sequencing and bioinformatic analyses of five typical rice landraces including three indica and two japonica with potential blast resistance. A total of 688.4 million 100 bp paired-end reads have yielded approximately 30-fold coverage to compare with the Nipponbare reference genome. Among them, a small number of reads were mapped to both chromosomes and organellar genomes. Over two million and eight hundred thousand single nucleotide polymorphisms (SNPs) and insertions and deletions (InDels) in indica and japonica lines have been determined, which potentially have significant impacts on multiple transcripts of genes. SNP deserts, contiguous SNP-low regions, were found on chromosomes 1, 4, and 5 of all genomes of rice examined. Based on the distribution of SNPs per 100 kilobase pairs, the phylogenetic relationships among the landraces have been constructed. This is the first step towards revealing several salient features of rice genomes in Vietnam and providing significant information resources to further marker-assisted selection (MAS) in rice breeding programs.

This study was conducted to develop the salt tolerance of rice by exogenous application of magnesium sulfate supplement (MgSO4). The salinization was carried out on 7-day-old rice seedlings including BC15 (salinity tolerant) and DT84DB (salinity susceptible) varieties with 0.5 mM MgSO4. The exogenous application of MgSO4 significantly improves the growth of seedlings of both varieties. In addition, antioxidant activities increase in line with the raise of total phenolic and total flavonoid contents. Remarkably, the contents of momilactone B (MB) and phenolic compounds including tricin, ρ-coumaric, salicylic, cinnamic, benzoic, and ferulic acids simultaneously rise in both varieties treated by salinity and 0.5 mM MgSO4. Interestingly, MB was not found in the salt-treated samples but presents with considerable contents in the salt and MgSO4-treated cultivars. The findings imply that MgSO4 may significantly improve the salt tolerance of rice seedlings through the enhancement of secondary metabolic synthesis pathways, of which phenolic acids and momilactone B may play a crucial role in the response of rice to salt stress. In contrast, momilactone A (MA) did not show any contribution in salinity tolerance of examined rice cultivars at the early seedling stage. Further investigations on the effect of MgSO4 exogenous application in improving salinity tolerance of various rice varieties at other growing stages should be carried out.

Salinity stress is one of the most severe constraints limiting rice production worldwide. Thus, the development of salt-tolerant rice promises to deal with increasing food demand due to climate change effects. This study investigated the salinity tolerance of mutant rice by evaluating phenotype and genotype, using forty-two simple sequence repeat (SSR) markers linked to the salinity tolerance Saltol quantitative trait locus (QTL) in ten cultivars and mutant lines. Results of phenotypic screening showed that the mutant line SKLo/BC15TB and cultivar BC15TB performed salt tolerance, while the mutant line Bao Thai/DT 84 and cultivar DT84DB were sensitive to salt stress. The markers RM 493, RM 562, RM 10748, RM 518, RM 237, and RM 20224 were the most polymorphic in salinity tolerance. Among them, RM 237, RM 10748, and RM 224 showed the highest polymorphism information (PIC = 0.58). This study reveals that the three markers are profitable for classification of salinity tolerance in both cultivar and mutant rice. The mutant line SKLo/BC15TB and cultivar BC15TB were found to be promising candidates for diversity analysis of salt-tolerant rice. Findings of this study are useful for developing new salinity-tolerant rice cultivars towards climate change.