Published: 2022-10-27

Effect of heavy metals on duckweed growth

Duc Thang Nguyen; Le Lan Anh Hoang, Thi Thanh Van Pham; Minh Tuan Nguyen, Thanh Hang Nguyen, Huu Phuoc Nguyen, Thuy Van Anh Huynh, Thi Nhung Tran, Thi Nhu Phuong Hoang
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In this study, three clones of the duckweed genus Lemna, collected from three different regions of Vietnam Binh Thuan Bac Giang and Ben Tre were used to evaluate the growth and development in a culture medium containing different concentrations of As3+, Cd2+, or Pb2+. During 14 days of incubation, the growth rate was determined daily by measuring the surface area of all plants of each sample. Experimental results show that the three Lemna clones could grow in nutrient medium contaminated by heavy metal at a concentration of 0.3-0.5 mg/L for As3+, 0.15-0.3 mg/L for Cd2+, and 0.15 mg/L for Pb2+. At these concentrations, the division rate of the treated clones was several times higher than that of the controls. The highest increase in the surface area was recorded for Lemna BTN (68.47 times higher when cultured in medium supplemented in 0.3 mg/L Pb2+ than under control conditions). The surface area of Lemna BTR cultured in a medium supplemented with 0.3 mg/L As3+ was 54.65 times higher than in medium without arsenic. The obtained results showed that Lemna BGG and Lemna BTR can tolerate arsenic and cadmium pollution while Lemna BTN tolerates lead pollution.

Morphological variation, chromosome number, and DNA barcoding of Giant Duckweed (Spirodela polyrhiza) in Vietnam

Ngoc Bao Tram Tran, Thi Nhung Tran, Thi Nhu Phuong Hoang
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Our present study is the first systematic survey on duckweed biodiversity in Vietnam. More than 100 samples of Spirodela, Lemna, and Wolffia were collected throughout Vietnam and maintained under laboratory conditions. In this report, the morphological variation, chromosome number, and DNA barcoding on Spirodela samples were investigated.  S. polyrhiza and S. intermedia are the only two species of Spirodela genus - the most ancient genus among the five duckweed genera. The obtained DNA sequences of atpF- atpH and psbK – psbI regions showed that all 29 Spirodela samples collected from different regions along Vietnam are S. polyrhiza. Specific SNPs of individual S. polyrhiza clones were identified in the psbK-psbI region. The differences in genome size (163 – 170 Mbp), frond size (0.80 – 1.25 cm2), frond shape (oval/circular symmetry/asymmetry), stomata (20.57 – 24.00 µm in length and 10.00 – 21.30 µm in width) and root number (4.75 – 6.69 roots) among six representatives S. polyrhiza clones were recorded. The chromosome number of these clones was uniformly 2n=40.

Bulbophyllum tseanum (Orchidaceae) a new record for the flora of Viet Nam

Dang Minh Quan, Averyanov V. Leonid, Dang Van Son, Nguyen Tran Vy, Truong Quang Tam, Nguyen Quoc Bao, Truong Ba Vuong
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Bulbophyllum tseanum found in Quang Nam Province  is recorded as new for the orchid flora of Viet Nam. Previously this species was only recorded in Hong Kong and Hainan (South-East China). Living specimens were collected from Quang Nam province and flowered successfully in a private garden in Da Lat city, Lam Dong province. Based on morphological characters, B. tseanum is very close to B. lepidum in  plant habit, shape and color scheme of flowers, but can be distinguished by its broadly ovate dorsal sepal, longer lateral sepals, narrow petals with shortly caudate apex, size of stelidia and column wing shape. The description of Vietnamese plants is presented, accompanied with the analytical plate and taxonomic notes.

Controlling efficiency of the potential rhizosphere bacterial antagonists against leaf spot disease from Rosa spp. caused by Xanthomonas spp. in vitro and under net-house condition

Uyen Thanh Le, Doan Thi Kieu Tien, Ngoc Tam Huynh, Lan Phuong To, Nguyen Thi Be Nhanh
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Bacterial leaf spots (Xanthomonas spp.) on roses cause great losses to farming. In vitro, the survey of antagonistic density was tested by using three antagonistic isolates (BR16, BR37, BR88) against Xanthomonas spp. (XR13, XR9, XR18 strains). These antagonists and pathogens were diluted separately at 10, 100, 1000 &10000 fold. Results showed that the inhibition abilities were increased with diminishing the population of the pathogen. In which, the antagonists with populations less than 106 CFU/mL are not sufficiently or low effective in forming the inhibitory zone against the pathogen. Therefore, a density of about 107 CFU/mL was selected in the trials on rose under net-house conditions. From that, with the foliar application, three isolates (BR16, BR37, BR88) were tested against the three mentioned pathogenic strains. Results showed that pretreating with antagonistic bacteria achieved high disease control efficiency. In which, BR88 has the highest disease reduction efficiency reaching 70.1%, 72.4%, and 73.3%, when infecting the XR13, XR9, or XR18, respectively. Furthermore, treatments from applying separately three antagonistic isolates all have AUDPC lower than the treatment with only disease inoculation from 2.4 to 4.7 times. In which, the AUDPC of treatment of BR88 was similar to BR16 when infecting XR13,...

Lithocarpus encleisocarpus (Korth.) A. Camus - A newly recorded from Vietnam and its phylogenetic relationship based on genome-wide SNPs

Ngoc Nguyen Van, Hoang Thi Binh
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A newly recorded Lithocarpus (Fagaceae) species for the flora of Vietnam, namely Lithocarpus encleisocarpus (Korth.) A.Camus was reported in this study. This species is most morphologically similar to L. dahuoaiensis Ngoc & L.V. Dung in having a completely entire leaf margin, solitary cupule, long stalks of fruits, deeply cup-shaped or turbinate cupules, with several horizontal filiform lines, but it differs from the latter by having cupules almost completely covering the nut, surface of the cupule densely fulvous tomentose by stellate hairs, secondary veins 8-10 pairs. This study provides the phylogenetic relationship of L. encleisocarpus with its close species based on genome-wide SNPs. Taxonomic treatment, photographs, information on distribution and habitat, and the GenBank accession number for DNA barcodes of the species are also provided.

The chromosome numbers of Panax vietnamensis Ha et Grushv

Xuan Tu Dinh, Le Huynh Thi Diem Suong, Minh Ly Nguyen
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The somatic chromosome number of Panax vietnamensis Ha et Grushv. was determined to be 2n = 24, based on the hypotonic shock method by potassium chloride solution. In this study, we investigated the effect of potassium chloride and colchicine solutions on chromosome dispersion of Panax vietnamensis at different concentrations. The treatment using 0.2% KCl solution in 45 minutes combined with 0.05% colchicine solution in 2 hours subsequently resulted in proper hypotonia. The result showed that chromosomes were evenly dispersed. The hypotonic shock method seemed to be effective in equally distributing chromosomes. The result can be applied in cell genetic studies and selective breeding programs for Panax vietnamensis.

Creation of Variation through In-vitro Mutagenesis using Gamma radiation in Rose (Rosa hybrida L.) Variety ‘Lửa’

Le Nguyen Lan Thanh, Nguyen Van Son, Le Van Hoa
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Rosa hybrida L. var. Lửa has been one of the most important roses for a long time and is most often used for ornamental purposes in Sadec city, Dong Thap province. The study aimed to induce variation through in-vitro gamma-ray irradiation in the rose variety ‘Lửa’ for further improvement in rose breeding. In-vitro single node cuttings (25 in-vitro cuttings per treatment with four replications) were irradiated with different doses of γ-rays (0, 5, 10, 15, 20, 25, or 30 Gy) using a 60Co source (India) at Da Lat Nuclear Research Institute. The γ-irradiated explants were then cultured aseptically on Murashige and Skoog’s basal medium supplemented with 1.0 mg/L BAP to induce multiple shoots, shoot proliferation, and acclimatization at Division of Vegetables, Flowers and Landscaping of Southern Horticultural Research Institute (SOFRI). The LD50 dose was determined at 20 - 25 Gy treatments and these doses affected the multiplication rate, growth in-vitro, and ex-vitro survival rate. Three types of mutants with altered or novel flower color in comparison to the original flower color were isolated, such as Type 1 with orange-pink (Red 52C), Type 2 with pink (Red 54B), and Type 3 with Red 45AB with Red 54B bicolor.

Semi-chronic toxicity study of the extracts from different parts of burmese-grape Baccaurea ramiflora fruits of Ha Chau variety using mouse model

Nguyen Hong Xuan, Nguyen Cong Ha
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This study evaluated the semi-chronic toxicity of seed, peel, and pulp extracts from burmese-grape fruits of Ha Chau variety on Swiss albino mice. The ethanolic extract from peels and seeds as well as fruit juice from squeezing pulp were dried under a vacuum to obtain the crude extracts. The distilled water (control group) or these extracts at a daily dose of 400 mg/kg of body weight were directly inserted into the stomach of mice for 90 days. The mice were observed for toxicity signs, externally morphological features of organs, and histopathology after 45- and 90-days of treatment. The results revealed that there were no toxicity signs and statistically insignificant differences in body weight gain, the ratio of organ weight to body weight, and blood glucose level at 45 days of treatment. At 90 days of treatment, similar results were observed, except that the ratio of kidney weight to body weight significantly increased in peel extract mouse group as compared to the control. The semi-chronic toxicity assessment showed that Ha Chau fruit (HCF) seed and pulp extracts were safe at a daily dose of 400mg/kg for 90 days in mice and that HCF peel extract was safe when orally...

Diversity of medicinal plant resources in Lai Son island, Kien Giang province

Dang Minh Quan, Nguyen Trong Hong Phuc
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This study was conducted with the aim of assessing the diversity of medicinal plants in Lai Son Island, Kien Giang province, which is a scientific basis for more effectively using, managing, and preserving this medicinal plant resource in this province. In this study, the PRA (Participatory Rural Appraisal), field investigation, morphological comparison, and classification, with the aid of specialized medicinal plant books were used. The results showed a total of 353 species of medicinal plants belonging to 264 genera of 112 families in 4 divisions. Among them, Magnoliophyta was the most diverse division with 94.90% % species, 95.08% genera, and 90.18% families. Seven species were listed in “Red List of Vietnamese medicinal plants” (2006), “Vietnam Red Book” (2007), and the Decree 06/2019/ND-CP. The medicinal plant species were divided into ten life forms and distributed in six biotopes. The most species diversity was recorded in the natural forest on rocky mountain biotope. Ten parts of plants were used to medicate 36 disease types. Twenty-four species were commonly used by local people.

Isolation and identification of the antagonistic bacteria against Xanthomonas spp. causing the leaf spot from Rosa spp.

Le Uyen Thanh
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Three out of 203 bacterial isolates showed high antagonistic activity by in vitro screening against three strains of Xanthomonas spp. causing leaf spots from Rosa spp.. Antagonistic bacteria were collected from the rhizosphere substrate of potted rose in Sa Dec Flower Village of Dong Thap province, Viet Nam. While three pathogen strains of Xanthomonas spp. were stored at the Biochemistry Laboratory of Biotechnology Research and Development Institute of Can Tho university. Three effective isolates were identified by Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and analysis of 16S rRNA gene sequence. Using MALDI-TOF, these antagonistic bacteria belong to Bacillus genera. The amplification of 16S rDNA gene was performed using 27F and 1492R primers. The nucleotide sequences of this gene were aligned using the GenBank database and BLAST-N program from the NCBI site. The isolates identity of BR16, BR37, and BR88 shared the highest similarity values in turn with Bacillus velezensis MN160320 (99.11%), Bacillus subtilis MN493770 (99.11%), Bacillus amyloliquefaciens KX871898 (99.41%). These Bacillus isolates were designed Bacillus velezensis MW677565 (from BR16), B. subtilis MW828613 (from BR37), B. amyloliquefaciens MW828656 (from BR88). These isolates have shown the ability to fight phytopathogenic bacteria of rose plants in Dong Thap of Viet Nam.

Histopathological characteristics of striped catfish (Pangasianodon hypophthalmus) in challenge with Edwardsiella ictaluri

Khang Luu Tang Phuc, Tran Thi Phuong Dung, Nguyen Huu Giau
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The present study attempted to understand the histopathological index of striped catfish (Pangasianodon hypophthalmus) in challenge with Edwardsiella ictaluri, the causative agent of bacillary necrosis of Pangasius. Total of 355 healthy striped catfish juveniles was challenged with E. ictaluri (25 control; 330 infected). After the challenge, a total of 355 samples of the trunk kidney, liver, and spleen were collected at five different time points including just prior to infection, 24, 48, 264 and 312 hours post-infection (hpi) to measure the represented tissue damage of the fish. Results showed that many areas of the diseased liver, kidney, and fish organ tissues have been congested and hemorrhaged early at 24 hpi. The number of macrophage centers in the kidney and spleen increased at 24 - 48 hpi. Tissue damage (multifocal hemorrhages; necrosis) increased sharply from the period 48 - 256 hpi. The increased number of dead fish throughout infection, particularly the period from 48 to 200 hpi. At 312 hpi, the histopathological index was the highest, so the mortality rate was the highest during the experimental period.

Efficacy of bacteriophages in controlling bacterial vascular wilt caused by Ralstonia solanacearum Smith on eggplants

Doan Thi Kieu Tien, Lu Chi Thong, Pham Van Luc, Nguyen Thi Thu Nga
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The objective of the study was selection promising bacteriophages for lysis Ralstonia solanacearum in vitro and evaluation their ability to prevent bacterial vascular wilt on eggplants under greenhouse conditions. Primary selection of promising bacteriophages from four bacteriophages as Φ54, Φ60, Φ67, and ΦBT on Ralstonia solanacearum isolated from eggplant based on plaque diameter and phage multiplication in in vitro, the result found that three bacteriophages (Φ54, Φ67, and ΦBT) expressed plaque diameter over 7.00 mm at 48 hours, and phage titer with log (pfu/ml) reach over 7.00. Continuing the survey, the efficacy of these phages in controlling bacterial wilt on eggplants in greenhouse conditions through applying each bacteriophage or cocktail of three phages suspension two times (1010 pfu/ pot/ each time) before pathogen inoculation and 7 days after pathogen inoculation through soil drenching.  As a result, all bacteriophages either single or mixture of three phages were effective in the prevention of bacterial wilt disease. Especially, phage Φ BT showed the highest disease reduction and was better than bacteriocide treatment applied with Starner 20 WP.

Quality profile of QSU-farm pond irrigation system: Its suitability as irrigation waters

Denson Liday, Nobelyn Agapito
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The quality of available water must be tested to check its suitability prior to its use. The physicochemical analysis of the QSU-farm pond water system has been done to assess its quality for irrigation needs. The quality analysis was made through the estimation of its temperature, pH, salinity, Total Dissolved Solids, Electrical Conductivity, alkalinity, chloride, hardness, iron, and sulfate as irrigation water criteria. The analytical data were processed and compared with the standard permissible limit set for irrigation waters. Regarding the suitability of the farm pond water system for irrigational purposes with the measured quality criteria, the farm pond waters were within the safe limits except for few parameters that did not meet the required irrigation standard limit criteria which need immediate attention. The quality profile results may be used as a basis for future management and strategic intervention.

Selection and characterization of a yeast strain for the suppression of brown spot on Tru Long pummelo (Citrus maxima)

Minh Ly Nguyen, Le Thi Mai
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Tru Long pummelo is an endemic plant of Quang Nam province with high economic value. However, many different diseases, especially brown spot disease caused by Alternaria fungus on pummelos, have affected the quality of pummelos. Pesticides are overused and misused for the environment and human health. Therefore, there is an urgent need to reduce the use of synthetic chemicals. Biological control offers an alternative to the use of pesticides. Eight yeast strains have been isolated from healthy leaves, pummelo fruits, and healthy mulberries. They were screened for biological activity against Alternaria sp. by the dual culture method. The inhibitory potency ranged from 10.46% to 59.86%. The strain with the highest percentage (59.86%) was identified as Candida tropicalis using sequence analysis of the ITS region.