Vol. 15 No. 1 (2017)

The present study aimed at regenerating cassava(Manihot esculenta Crantz) via somatic embryogenesis. The explants used were immature leaves harvestedfrom 2-3-week old in vitroplantsderived from two cassava cultivars, KM94 andKM140. Somatic embryogenesis was achieved with high frequencies usingMS medium supplemented with a wide range of picloram concentrations. The results showed that the highest rate of somatic embryo formation for both cultivars was obtained when cultured in MS mediumcontaining 12 mg/l picloram. Although the number of embryos per explant was similar between two cultivars at4 weeksof culture, KM94 cultivar gave a higher rate (81,4 ± 1,7%) than KM140 cultivar (70,4 ± 2,9%). Somatic embryos were subsequently transferred to MS medium supplemented with 0.3 mg/l BAP for plantlet regeneration. All shoots with 1.0-1.5 cmin length transferredto - hormone-free MS medium formed roots in 2 weeks. Rooted plantlets were transplanted toa mixture of rice husk (40%) and sandy soil (60%) in greenhouse. This protocol required 16 to 18 weeks and was entirely appropriate for mass production of various cassava genotypes and further genetic transformation experiments.

The major problem encountered in F1 hybrid seed production using cytoplasmic male sterile (CMS) lines is the incomplete panicle exsertion at a rate of 30-60% depending on genotype. Application of exogenous GA3 is often required to overcome this problem. A recessive mutant gene (eui) that causes elongation of the uppermost internode at heading stage can be used as a genetic approach to GA3. In this study, DNA markers were used to identify and screen rice plants with eui gene in CMS lines and in F2 segregating and BC1F1 population. The results showed that 6 CMS lines, 12A, L1A, L2A, L3A, L4A and L5A contained eui gene. Phenotypic and genotypic analysis of F2 and BC1F1 population confirmed that elongated uppermost internode trait was regulated by a single recessive gene and followed of Mendelian segregation ratio..

A pot-experiment was conducted using completely randomized design (CRD) with 5 replications in green house at Faculty of Agronomy, Vietnam National University of Agriculture in autumn season 2016 to evaluate morphological and anatomical characteristics of DCG66 line that caries a chromosome segment substitution from cv. Asominori. Experiment used four entries: cv. Asominori (Subsp. Japonica), cv. IR24 variety (subsp. Indica), IAS66 line - a chromosome segment substitution line (CSSL) derived from IR24 and Asominori cross at BC2F3 generation, and DCG66 line - chromosome segment substitution line seleclted from IAS66 at BC2F8 generation. At heading stage, 5 plants per entry were randomly selected to measure morphological and anatomical characteristics of root, basal internode, panicle internode and flag leaf. At maturing stage, 5 plants/replication were selected to measure yield components and individual yield. The results showed that DCG66 outyielded by 11.5% compared to IR24, 53.5% to Asominori and 29.1% to IAS66 because of large spikelet/panicle. The stem internode diameter, root volume, total of root surface area, number of flag leaf vascular bundles were higher in DCG66 than other entries. There was a positive correlation between number of vascular bundles in panicle and yield components and individual yield at all of research varieties.

Afield trial was conducted from March to October 2014 in the experimental area of Agronomy Faculty, VNUA. The research aimed to determine photosynthesisand dry matter assimilation rateat corm initiation and corm bulking stages of 16 tarovarieties collected from the northern part of Vietnam. The results showed that: (1) CO2exchange rate (CER) atthe beginning of rapid root and shoot development with corm initiation was higherthan that inother phasesdue to lower radiation and temperature at the beginning of spring season. (2) A strong negative correlation was found between CER and intercellular CO2concentration (r= -0.91) at the beginning of rapid root and shoot development with corm initiationHowever, there existed arelatively strong correlation between CERwith stomatal conductance (r= 0.74) and leaf transpiration rate (r= 0.84) atthe beginning of the senescence period. (3) Thre was astrong positive correlation between NAR and CGR (r= 0.66) at the beginning of rapid root and shoot development with corm initiation, in contrast, a strong negative correlation of that were foundatthe beginning of the senescence period. (4) Two varieties: Hau Xit and ToHau performed highest yieldand showedhigh and uniform cormgrowth rate throughoutgrowth and development, even at the beginning of the senescence.period.

Growth hormone secretagogue receptor (GHSR) is one of the candidate genes for meat quality of chicken. The study focused on the association between the genetic polymorphism of the GHSR gene with meat quality traits in Tau Vang chickens. Two polymorphisms at nucleotide G656A and C3678T were identified by PCR/RFLP technique using restriction enzyme MspI and Bsp119I, repectively. The genotypic frequencies at G656A and C3678T loci were found in Hardy-Weinberg equilibrium. The study showed that the G656A polymorphism exerted influence onash content of breast muscleand there wassignificant associations between C3678T polymorphism and dry matterandether extract of leg muscle in Tau Vang chickens.

The study was conducted to investigate molecular biological characteristics of isolated canine distemper virus (CDV) strains from some provinces in the North of Vietnam. Five virus strains in this study were isolated from clinical samples of dogs infected with CDV in Nam Dinh, Thai Binh, Hung Yen, Hanoi and BacGiang provinces in 2015. After the viral ARNs were extracted from tissue samples, RT-PCR and PCR-sequence assay were performed using specific primer pairs to amplify haemagglutinin (H) and phosphoprotein (P) genes of CDV. The products of PCR-sequence were directly sequenced using Sanger sequencing method. The sequence of H and P genes was 1824bp and 402bp in length, respectively. The high similarity of nucleotides in H and P genes between 5 virus strains was 90.05 - 99.61% and 94.81 - 99.75%, respectively. The high similarity of amino acids encoded by H and P genes between 5 virus strains was high with 89.38 - 99.5% and 92.47 - 100.0%, respectively. The phylogenetic trees showed that five isolated virus strains belonged to three different genotypes: Asia 1, Asia 2 and Classic. These results indicated that pathogenic genotypes of virus strains were circulating in northernprovinces of Vietnam. These results are useful information for producing vaccine from pathogenic virus strains to control CDV in Vietnam.

This study aimedat examining the model of integrated culture of whiteleg shrimp with red tilapia in the context of climate change (CC), an expectation for a good model for the local farmers to deal with climate change. The experiment was carried out in six ponds, ranging from 2000 to 2500 m2, in 2015 and 2016, in Giao Phong commune, Giao Thuy district, Nam Dinh province. The trials consistedof 6 models designed in six ponds: two integrated farms in freshwater, and four monoculture shrimp farms for control, two in brackish water and two in freshwater. In the integrated culture models, red tilapia was added at a density of 2 fish per m2to a pond stocking 100 white shrimp per m2; the shrimp were stocked twice but red tilapia was stocked only once per year. In the monoculture models, whitelegshrimp was stocked at the same time and the same density as those in the integrated models. Comparingto the monoculture of shrimp in both brackish and fresh water, the polyculture of shrimp with red tilapia where whitelegshrimp was acclimatized to fresh water resulted in lower disease incidence, reduced the cost of drugs and chemicals by about 30%, and gained more than doubled the economic benefits. Farmers and the local authorities in the district highly appreciated the results of the integrated culture model. This model can be considered as a strategy to increase the adaptive capacity of aquatic production in the study area.

This study aimedto assess and identifycoastal shrimp farming modelsthat are sustainable under climate changeconditions in Quynh Luu, Nghe An. The evaluation criteria focusedon infrastructure (6 criteria), culture techniques and cage management (7 criteria), and awareness of and response to climate change (2 criteria). Each criterion was assessed andscored on a 5 point scale (5 = very good, 4 = good, 3 = average, 2 = poor, 1 = weak). The assessment results found that most criteria were averaging upwards, except criteria on influent and effluent systems, reservoir and site location of the shrimp farm TNT2. Coastal shrimp farms (TNT1, TNT6) had a high overall score and thus can be selected as the coastal shrimp farming modelsfor the coastal shrimp farming community in this location.

Predicting genes which may associate with disease is one of the important goals of biomedical research. There have been many computational methods developed to rank genes involved in a particular disease. However, due to the complex relationship between genes and the diseases, many genes that cause genetic diseases have not yet been discovered. The problem of ranking genes to identify the disease-associated gene has drawn attention of many researchers. To find a good method to predict target genes that cause diseases with high performance, we have conducted a survey of prediction methods based on biological network. We then proposed a new method using a Boolean network model. In biological network, defects by mutations on genes/proteins may cause a disease to occurin a person. Also, these mutations may affect other genes/proteins through structures of the biological networks. In this study, we proposed to use Boolean network model to assess the relevance of candidate genes to a disease of interest by measuring the degree of mutational effect from known disease-associated genes to candidate genes. Particularly, we mutated known disease-associated genes and measured the effect of this mutation on candidate genes based on Boolean dynamics of biological networks. Based on this measured value, candidate genes can be prioritized and finally top-ranked candidate genes can be selected as novel promising disease genes. Simulation results on a set of diseases showed that the proposed method is superior to a state-of-the-art one, which is based on a random walk with a restart algorithm. Using the proposed method, we have identified 27 genes associated with breast cancer with evidences from literature.

In this study, 221 colonies have been isolated from 3 samples of cow rumens collected from Le Chi - Gia Lam, Khoai Chau - Hung Yen, and Phu Xuyen - Ha Noi. 94 strains primarily identified as Bacillusspp.were used to determine β-glucanase activity. Results indicated that most of them produced extracellular β-glucanase and the strain PX.07 secreted enzyme with highest enzyme activity at 6.8U/ml. The enzyme was purified from medium culture using 50% saturated (NH4)2SO4 and then used for further characterization. Optimal temperature and pH of the purified enzyme were 60oC and pH 6,respectively. The enzyme is stable when incubated at temperature range of 30-60oC and pH of 3 -6.

Wild bitter melon (Momordica charantia L. var. abbreviata Ser.) is known as a valuable vegetable and herb. It contains several important bioactive substances, including glycoside, saponin, alkaloide, triterpen and steroide. This study was carried out to establish a simple and efficient transformation protocol for inducting hairy roots of wild bitter melon by using strain TR7 of Agrobacterium rhizogenes which carries pPE113 binary vector harbouring e-gfp gene. Major parameters were optimized including, the age of plant and position for injection. The results indicated that highest hairy root induction frequencies was about 69.66-73.33% when seven-day-old seedlings were used to infect with the bacterium using hypocotyl. After regeneration and selection, thirty putative root clones of 4 specific phenotypes, i.e. white hairs, fast growth and branching on hormone-free MS medium, were obtained. The average GFP expression rate in 4 specific phenotypic groups were about 46.7%. PCR analysis using specific primers for rolA gene and virD gene confirmed the presence of the rolA gene and absence of virD gene in the genome of four hairy root lines. It was suggested that this simple transformation protocol can be applied for hairy root induction of other varieties as well.

Mustard greens(Brassica juncea(L.)Czern.) is widely grown and plays an important role in local vegetable production. However, drought has serious effecton growth and development of mustard greens. This research aimedto examine the role of moisturizing polymers on growth, development and drought tolerance in mustard greens. Results showed that the use ofsubstratecontaining moisturizing polymers helped maintain humidity in the soilandcreateright conditions for seed germination and plant health. Substrates supplemented with 5% of moisturizing polymers yielded the highest rate of germination (91.11%), good plant growth (21.75cm of plant height, 22.09 cm of canopy diameter, 6.73 of leaves number, 12,10 cm of leaf width, 21.17cm of leaf length, 185.64cm2of leaf area), and highest leaf yield (61.41g/plant). Addition of polymers also helped retain soil moisture and lower moisture loss and improve plant growth. 10 days after water withholding, proline concentration increased only 3.6 times in the plants grownin medium containing 5% of moisturizing polymes whereas it increased 93 times in control plants.

Sampling 193 fresh milk customers in Gia Lam district and using EFA, CFA, and SEM analysis methods, the Vinamilk’s fresh milk customers’ loyalty was built based on four components: product quality, perceived price, company imange and promotion programs. This study also ranked the factors affecting to the customers’ satisfaction, trust and loyalty. Customer’s satisfaction was affected, in the order, by price, promotion program, product quality and company image; the customer’s trust was affected by company image, product quality, promotion program and price. Both customers’ trust and satisfaction affected customers’ loyalty. To maintain and enhance customers’ loyalty, Vinamilk should improve the customer satisfaction and customer trust with prioritized implementation of the following solutions: Maintaining and enhancing the company image, constantly improving product quality, offering affordable price, and expanding the promotions.

This article aimed to analyze the economic efficiency of the outdoor production of straw mushroom (Volvariella volvacea) in Long My District, Hau Giang Province. The authors conducted face-to-face interviews of 180 straw mushroom growers in four largest straw mushroom growing communes in Long My District, Hau Giang Province in April - May, 2015. The survey showed that the straw mushroom cycles were 3.9 ± 2,0per year, of which 59% of the surveyed households grew straw mushroom in the whole year. 12% of the quantity of rice straws used for growing straw mushroom were from their own rice production and the rest of 88% were purchased from rice straw collectors or providers. 68% of the survey households harvested straw mushroom in dry season of 2015 and 32% in the rainy season 2014. The average yield of straw mushroom was 35 ± 10 kg/kg straw (dry weight) (3,5± 1,0% materials). The total cost of straw mushroom production was 1,001 ± VND 682 thousand/ton straw/cycle (58% of the total cost is non-cash cost). The gross income was 1,057 ± 350 thousand VND/ton, net income is 596 ± VND 335 thousand /ton straw/cycle and profit is - 44 ± VND 704 thousand /ton straw/cycle. The major constraints in growing straw mushroom in this area were weather dependence due to to outdoor mushroom production, low spawn quality, lack of capital investment and advanced mushroom growing techniques increased price of rice straw and unstable selling price of straw mushroom.

There are several factors affecting the competitiveness of tuna exported from Vietnam to the world market. In the U.S market, tuna price has been increasingly recognized as the main factor affecting the competitiveness of tuna exported from Vietnam. Tuna export price from Vietnam depends mainly on three factors, namely domestic tuna material price, exchange rate, and world tuna price. The study aimed to analyze the impact of the three factors on the competitiveness of tuna exported from Vietnam to the U.S market during 2006 - 2015 period. The results provide an overview on price competitiveness of tuna exported from Vietnam to the U.S market, which serves as a scientific background for policy makers and authorities in designing policies for efficient and sustainable development of tuna commodity chain.