Search

In this study, silver nanoparticles effects on the sterilization of different sources of explants (young leaves, young flower stalks and young flower buds) of Gerbera as well as on the in vitro morphogenesis and their growth were investigated. The explants were sterilized and cut transversally (1 mm) with the flower stalk, square (0.5 × 0.5 cm) for the leaf sample, longitudinally (0.5 mm) for the flowers (removed the petals) and cultured on MS medium; then, the explants (contamination-free or no browning/necrosis) were transferred into MS medium supplemented with 0.02 mg/L TDZ plus 0.8 mg/L adenine, 10% coconut water, 30 g/L sucrose and 8 g/L agar in 15 days. The results showed that AgNPs at the appropriate concentration and duration treatment was effective in explant sterilization of flower bud (0.02% AgNPs and 20 min), flower stalks (0.02% AgNPs and 30 min) and young leaves (0.05% AgNPs and 20 min) after 15 days of culture. In addition, 3 types of morphogenesis including callus induction, somatic embryogenesis and direct shoot regeneration of explants derived from sterilization by AgNPs were improved as compared to that of HgCl2. In addition, research on the optimal medium for shoot multiplication, rooting as well as evaluation of acclimatization and the growth at the greenhouse were also studied. Results showed that MS medium supplemented with 2 mg/L NAA combined with 0.5 mg/L BA and 2 mg/L KIN is suitable for shoot multiplication; meanwhile, MS medium supplemented with 2 mg/L NAA improved rooting ability as well as quality of plantlets and to improving survival rate and acclimatization of Gerbera cultured in vitro.

Saintpaulia ionantha Wendl. is a small flower, with a variety of colors, which are commonly grown indoors for decorative purposes. Currently, micropropagation of S. ionantha has been achieved certain results; however, the shoot quality as well as number of shoots regeneration was not high. In this study, the effect of LEDs system on the shoot multiplication and shoot quality of S. ionantha was conducted. The leaves were cut into square patterns without the main veins (1 cm × 1 cm), and the petiole (3 mm in diameter) was cut with a thick layer (2 mm) of longitudinal cell (lTCL), which were used as the initial materials. The explants were placed under LEDs conditions; and white fluorescent tube lamp (FL) was used as the control for shoot regeneration and rooting. The results found that the quality of light affects the regeneration, growth and development of S. ionantha shoots. The LED condition with a combination of 7R + 3B are optimal for high-frequency of shoot regeneration with the regeneration rate: 67.25%, and number of shoots: 9.33 shoots/explant from the leaves without the main veins. The higher shoot multiplication (number of shoots: 10.00 shoots/explant, fresh weight: 150.07 mg, dry weight: 98.64 mg) and rooting rate of plantlet (fresh weight: 2.17 g; dry weight: 0.09 g; leaf number: 20.33 leaves/plantlet) were also obtained under 7R + 3B condition.

The growth of strawberry plantlets in the rooting stage on culture medium supplemented with silver nanoparticles (AgNPs) and the ethylene gas accumulation in plantlet culture bottles were investigated. In addition, different culture systems were first used to produce large-scale Strawberry plantlets. The results showed that shoots (3 cm) were cultured on MS medium supplemented with 0.02 mg/L NAA, 1 g/L activated charcoal, 30 g/L sucrose, 8 g/L agar and 0.5 mg/L AgNPs showed about 4 days earlier rooting formation and the plantlet growth such as plantlet height (5.60 cm), fresh weight (242.67 mg), dry weight (34,67 mg), number of roots/plantlet (6.67), root length (3.40 cm), SPAD (39.30 nmol/cm2) were higher than those in the control after 15 days of culture. Besides, the ethylene gas content in the culture bottle (0.06 ppm) in the 0.5 mg/L AgNPs treatment was lower than as compared to that in the control (0.15 ppm) after 15 days of culture. A shoot density (10 shoots) in 250 mL culture bottle with 40 mL of medium gave optimal growth than those in other treatments after 15 days of culture. Square plastic box culture system (length × width × height: 19 cm × 19 cm × 7 cm; 2.5 L in volume) containing 250 mL MS medium added to 0.5 mg/L AgNPs produced 100 vigorous plantlets; meanwhile, rectangular plastic box system (34 cm × 23 cm × 13 cm; 10 L in volume; 10 L in volume) produced 200 vigorous plantlets. Plantlets derived from 0.5 mg/L AgNPs treatment in the plastic box systems exhibited well acclimatization after 30 and 60 days of culture in the greenhouse.

In this study, a new method for shoot regeneration via protocorm-like bodies (PLBs) is described. Shoot proliferation using stem elongation under light-emitting diodes (LEDs), and enhanced growth of Anthurium andraeanum ‘Tropical’ plantlets on medium containing silver nanoparticles (AgNPs) was investigated. For shoot regeneration, the micropropagation efficiency via PLB formation was fourfold more efficient than directly from callus after 12 wk of culture. This was possible because each initial callus cluster could be cut into 20 explant slices (1 × 5 × 5 mm in size), each with an average of 42.67 PLBs which are capable of growing into plants. For shoot proliferation, single shoots with 2 cm in size derived from PLB culture were placed under different blue to red LED ratios. This study showed that higher shoot height (4.77 cm), fresh weight (327.33 mg), number of leaves per shoot (6.33), and the number of stem nodes per shoot (5.67 stem nodes) were obtained under 70R:30B as compared to those under other lighting conditions and fluorescent lamp after 8 wk of culture. Especially, the total shoot proliferation (10 shoots) via stem node culture was higher than those in the control. For enhanced plantlet growth, single shoot with a pair of leaves derived from stem elongation under 70R:30B cultured on 1/4 MS medium supplemented with 0.5 mg L−1 NAA and 1 g L−1 activated charcoal, 7 mg L−1 AgNPs, 30 g L−1 sucrose, and 8 g L−1 agar gave the highest growth than other treatments. Plantlets derived from 7 mg L−1 AgNP treatment transferred into greenhouse showed better growth as well as 4-wk earlier flowering than the control treatment.

Dendrobium officinate Kimura et Migo, a species of orchid for beautiful flowers, is used in traditional medicine in many Asian countries because there are many important pharmaceuticals (chrysotoxene, erianin, confusarin, polysaccharide, alkaloid ...) in anti-cancer, anti-aging, boosting immunity and vasodilation, etc. In recent years, more than 4,000 hectares of Dendrobium officinate Kimura et Migo artificial planting has been available in China and the price of dry product was around ¥ 80,000/kg. Currently, plantlet quality is an important factor influencing the acclimatization stage, growth, and development of plants in the greenhouse. In this study, the effect of a number of factors medium, plant regulator, ventilation, and substrate to improve plantlet quality as well as further growth and development in the greenhouse conditions were investigated. The results showed that SH medium was suitable for in vitro shoot growth in terms of monitoring parameters after 90 days of culture. In shoot multiplication stage, the shoots culture on SH medium supplemented with 2 mg/L BA, 30 g/L sucrose, 9 g/L agar, 1g /L activated charcoal (AC) gave the best results with 4.53 shoots/per shoot. The SH medium supplemented with 1.0 mg/L NAA, 30 g/L sucrose, 9 g/L agar, 1.0 g/L AC combined with ventilation conditions was suitable for rooting stage with plant height (5.73 cm), number of roots (4.77), root length (5.00 cm), fresh weight (3.36 g), dry weight (0,31 g), and total chlorophyll (SPAD) (45.76 nmol/cm2). Plantlets derived from culture ventilation conditions cultivated on the mixture of pine bark and fern fiber (50:50) was the highest survival rate (100%) and growth after 12 months in the greenhouse.

In vitro culture establishment is one of the most important stages in micropropagation. The disinfectant effectiveness depends on the type of surface disinfectant, concentration and the time treatment. In this initial study, silver nanoparticles (AgNPs) were used as a disinfectant for petioles, flower stalks and stems of Begonia tuberous. In addition, thin cell layer culture (TCL) technique has been applied for the purpose of somatic embryogenesis. The results showed that AgNPs were effective in eliminating infectious microorganisms on B. tuberous explants; which were identified included 4 species of fungi (Fusarium sp., Aspergillus aculeatus, Trichoderma sp. and Penicillium sp.) and 1 species of bacteria (Pseudomonas sp.). At concentrations of 200 ppm and 300 ppm, AgNPs were not only effective in disinfection but also increased the induction rate of somatic embryogenesis in flower stalk TCL explants (approximately 40.00%); a similar effect was observed in stem TCL explants at the same concentration. Meanwhile, for petiole TCL explants, the induction rate of somatic embryogenesis was optimal when using AgNPs at a concentration of 100 - 300 ppm to disinfected the explant. In contrast, at high (400 ppm) or low (50 ppm) concentrations of AgNPs did not play a disinfecting role and stimulated somatic embryogenesis. In addition, explants derived from AgNPs sterilization did not show any abnormalities in somatic embryogenesis with shapes such as globular, heart, torpedo, and cotyledon. AgNPs showed double efficacy in sterilization of explants and improved efficiency of somatic embryogenesis from TCL petioles, flower stalks and stems explants; thus increasing the efficiency micropropagation of B. tuberous.

Artichoke (Cynara scolymus L.), a medicinal plant with high economic value, contains high levels of phenolic compounds; especially cynarine, which plays an important role in preventing cancer, cardiovascular disease, osteoporosis, diabetes and neurodegeneration, etc. Currently, Artichoke micropropagation has achieved some success; however, the rooting efficiency and plantlet quality are still limited. In this study, improving the quality of Artichoke plantlet related to the shoot quality and suitable substrates in in vitro rooting stage was studied on “Violetta” Artichoke (VA) and “Green Globe” Artichoke (GA). The results showed that shoots (1.5 cm) cultured on MS medium supplemented 0.5 mg/L KIN were most suitable to shoot multiplication of VA with the number of shoots/explant (3.67 shoots), number of shoots ≥ 2 cm (3 shoots); while, 1.0 mg/L BA was suitable to shoot multiplication of GA (5.33 shoots; 5.00 shoots; respectively) after 4 weeks of culture. Besides, the in vitro rooting was improved using 8 g/L commercial agar for VA; meanwwhile, 3 g/L gelrite for GA. In addition, the nylon bag culture system (120 mm × 250 mm) has potential in plantlet production (15 plants/bag) and can be applied for large scale micropropagation. In addition, VA and GA plantlets derived from in vitro culture gave the good acclimatization, growth and development after 8, 12 and 20 weeks cultivating at the green house conditions.

Artichoke (Cynara scolymus L.), a high economic value crop, was brought to Vietnam by the French in the late 19th century. The artichoke was mainly planted in Lam Dong, Lao Cai, Vinh Phuc provinces, etc. At present, the disease situation of Artichoke plants and the lack of disease-free seedlings result in insufficient source of Artichoke for producers. Artichoke plants are mainly vegetative propagation and pathogens easily transferred from mother to daughter plants. Therefore, low propagation rate and fungal infection are two main factors hindering the expansion and development of Artichoke cultivation (in Lam Dong). Therefore, studying and evaluating the situation of fungi and viruses as well as establishing the in vitro propagation procedures in order to produce high number of disease-free seedlings are urgent for the current Artichoke shortage. In this study, samples of purple and white Artichoke varieties, which suspected fungal manifestations, were collected to assessment of fungi and viruses in artichoke. In addition, in vitro propagation by cultivating apical meristem was applied to produce disease-free seedlings. The recorded results showed that, 19 strains of mold were identified on purple and white Artichoke belonged to nine genera including Mucor (M. sp., M. circinelloides, M. fragilis, M. irregularis, and M. racemosus), Alternaria (Alternaria sp., A. alterinata, A. gaisen, A. tenuissima, and A. tillandsiae), Fusarium (F. acuminatum and F. solani), Cylindrobasidium (Cylindrobasidium sp1 and Cylindrobasidium sp2), Actinomucor elegans, Curvalaria clavata, Plectosphaerella oligotrophica, Phoma herbarum, Rhizomucor variabillis; meanwhile, the Tomato mosaic virus (ToMV) was isolated only purple Artichoke. Shoot explants obtained from apical meristem culture were completely disease-free and used for micropropagation at the next stage.

Effects of silver nanoparticles (AgNPs) on somatic embryogenesis and plantlets with rhizome of Panax vietnamensis were presented in this study. The highest number of somatic embryos (140) was obtained on MS medium containing 1 mg/L 2.4-D, 0.5 mg/L NAA, 0.2 mg/L Kin and 1.6 mg/L AgNPs. Plantlets with rhizome growth enhanced on SH medium supplemented with 1 mg/L NAA and 1.2 mg/L AgNPs and limited the ethylene gas content in the culture flasks. A low concentration of ethylene gas (0.92 ppm) stimulated plantlets with rhizome growth and development, and provided positive effect on the formation and quality of plantlets. The rhizome size of the plantlets in 1.2 mg/L AgNPs treatment was larger than those in the control without AgNPs. Plantlets acclimatized on the soilless substrate were higher survival rate (93.65%) as compared to the control (44.44%) after one year in the greenhouse. In particular, the rhizome saponin content was doubled compared with that in the planlets without AgNPs after 4-year planting in the greenhouse. These results may be scaled up for micropropagation of this important medicinal plant. AgNPs improved somatic embryogenesis. AgNPs enhanced plantlets with rhizome. AgNPs limited ethylene accumulation during micropropagation. AgNPs increased the survival rate of plantlets with rhizome in the greenhouse. AgNPs increased saponin content of plantlets with rhizome.

One of the common problems in strawberry (Fragaria × ananassa) micropropagation is the vitrification phenomenon (succulent plantlets, brittle stems, yellow leaves, etc.) leading to the reduction of plantlets quality and low survival rate in the greenhouse. In this study, the effects of silver nanoparticles (AgNPs) on explant disinfection, in vitro growth (shoot multiplication, and root formation), runner formation as well as ethylene accumulation during micropropagation of strawberry were investigated. The results showed that leaf explants treated with 200 mg/L AgNPs solution for 20 min was more effective in explant disinfection and shoot regeneration than using 1 g/L HgCl2. In addition, AgNPs stimulated the growth of shoot and plantlet and as well shortened the duration of root formation (4 days) as compared to those in control without AgNPs during micropropagation. Besides, AgNPs reduced the ethylene gas accumulation in the culture’s vessels of shoots (0.66 ppm) and plants (0.06 ppm) compared to controls (1.77 ppm; 0.15 ppm; respectively). Moreover, AgNPs combination with culture period (5; 10 or 15 days) effect root formation stage and acclimatization in the greenhouse. The plantlets that cultured on MS medium supplemethed with 0.5 mg/L AgNPs during 10 days showed higher survival rate (93.33%) after 15 days as well as runner formation per plant (8.00 runners) after 60 days in greenhouse than those in control. AgNPs improved explant disinfection and in vitro growth. AgNPs improved runner formation in the greenhouse. AgNPs limited ethylene accumulation during micropropagation.

In this study, morphogenesis and anatomy of adventitious roots and hairy roots of Ngoc Linh ginseng (Panax vietnamensis Ha et Grushv.) were compared. Adventitious roots were derived from four different samples (leaf, petiole, root and callus) in vitro cultured on medium SH supplemented with 5 mg/L IBA. Hairy roots were derived from callus infected with Agrobacterium rhizogenes strain ATCC 15834. The results showed that there were significant differences in morphogenesis and anatomy, the pathway of secondary roots formation, culture medium between adventitous roots and hairy roots. The hairy roots strongly grew and branched on the free-plant growth regulator medium. The secondary root of the hairy root was formed in two pathways: (1) The secondary root formation began at the vesicles system of main root; (2) The secondary root formation was independent of the vesicles system of main root; it kept developing in length and connected to the vesicles system of main root. On the other hand, growing adventitous roots only grew on the environment with exogenous auxin supplementation; also their branching ability were low. The secondary root formation of the adventitous root was started at the vesicles of the main roots and there was only one secondary root that was formed at an location of adventitous root. The results that obtained in this study will be the reference to identify two types of root.

Somatic embryo is a developmental method for mass multiplication of valuable medicinal plants. In this study, leaf explants of Ngoc Linh ginseng were disinfected with nano silver at different concentrations and exposure times to eliminate infectious agents and induce embryogenic callus for the production of somatic embryos. The results show that the lowest contamination rate (20.00%) was observed when leaf explants were treated with 0.5 g/L nano silver for 15 minutes while the highest embryogenic callus induction rate (72.22%) and fresh weight (0.77 g) was determined at 0.2 g/L nano silver for 20 minutes. High frequency of somatic embryogenesis formation and germination were occurred on MS medium supplemented 1.0 mg/L 2,4-D; 0.5 mg/L NAA; 0.2 mg/L Kin and 1.6 mg/L nanosilver. After 8 weeks of culture, the number somatic embryos derived from nano silver treated-leaves was increased 2 times than non-treated explants. Addition of 1.0 mg/L NAA and 1.2 mg/L nano silver was showed the highest shoot and root length, root number, fresh and dry weight of plantlets. This research showed that pre-treatment and supplement of nano silver in culture medium is potentially useful for improving embryogenesis frequency, and plantlet formation of Ngoc Linh ginseng cultured in vitro.

In plant tissue culture, iron nanoparticles (FeNPs) was one of the first types of nano to be used in plants. Previous reports have identified the effect of FeNPs on many different plant species. In this study, FeNPs was used to replace Fe-EDTA in MS (Murashige, Skoog, 1962) medium to assess their effects on growth, chlorophyll (a, b and a+b) accumulation, antioxidant activity of ascorbate peroxidase (APX) and superoxide dismutase (SOD) enzymes, and acclimatization in greenhouse conditions in different culture systems (in vitro solid, in vitro hydroponic and microponic culture). The obtained results show that FeNPs added to MS medium was higher growth, chlorophyll (a, b and a+b) content, antioxidant activity of SOD and APX enzymes than Fe-EDTA in MS medium as control treatment. The effect of FeNPs are differences between culture systems. In vitro solid and microponic culture systems, the optimal concentration is 75 mM FeNPs and in vitro hydroponic culture system is 100 mM FeNPs. The optimal activity of the antioxidant enzyme SOD (35.04 U.mg−1 prot) obtained in the roots of cultured plants in microponic culture system; meanwhile, the optimal activity of the antioxidant enzyme APX (2.11 μmol.min−1.mg−1 prot) obtained in leaves cultivated in solid culture system. The plantlets derived from MS medium added FeNPs were transfered into greenhouse conditions, the microponic cultivated plants supplemented with FeNPs at a concentration of 100 mM gave the highest survival rate (94.67%). The results of this study showed that FeNPs can replace Fe-EDTA salt in MS medium, and iron deficiency in culture media will reduce chlorophyll content.

Polygonum multiflora Thunb. (Belongs to Polygonaceae family) is a medicinal plant of economic value and should be protected, according to the Red Book of Vietnam. Many studies have shown that P. multiflora Thunb. was effective for many diseases such as hair loss, premature gray hair, lower back pain, knee weakness, muscle weakness, hemiplegia, nervousness, dizziness, insomnia, etc. Propagation and preservation of this herbal species are significantly important because of increased demand. Adventitious root biomass culture has been successful on a number of plant species, and that it has potential for P. multiflorum breeding. In this study, the effect of explants, plant growth regulators and different culture systems on adventitious root formation was investigated. The adventitious roots were induced from the explants and the optimum culture medium were transferred to four different culture systems (3-liter triangular flask, shaking triangle, bioreactor self-made and Korean bioreactor) containing 5 g adventitious roots per 1 liter medium. The results showed that the leaf cultured on SH medium supplemented with 1.5 mg L-1 IBA, 30 g L-1 sucrose, 8.5 g L-1 agar and pH 5.8 gave the higher of adventitious root regeneration rate (100%), root number/explant (25.33 roots), fresh weight (131.67 mg) and dry weight 13.35 mg) compared to those cultured on other condition after 6 weeks of culture. The adventitious root multiplication in the Korea bioreactor system is more effective than other culture systems shown in the fresh biomass (17.04 g), dry biomass (1.56 g) and proliferation rate (3.40 fold) after 6 weeks of culture.

Jewel orchid (Anoectochilus setaceus Blume) is one of the important medicinal plants used for many common diseases treatment such as hypertension, diabetes, and heart, liver and lung diseases, as well as improving the health in general. Polyploid induction using colchicine and oryzalin has been widely performed in various types of crops and could be considered a valuable tool for plant breeding. In the present study, in vitro young shoots of A. setaceus Blume (1 cm in height) were treated with different concentrations of colchicine (0, 1, 2, 4, 6, 8, and 10 µM) and oryzalin (0, 10, 20, 40, 60, 80, and 100 µM) at different durations (0, 12, 24, 36, and 48 h). The results showed that shoots with length of treatment from 24 to 48 h and the concentrations from 2 to 10 µM of colchicine and from 40 to 100 µM of oryzalin appeared morphological differences (10.00% - 16.00%) but the tendency to return to normal of these shoots after several times of sub-culture was observed. Stomatal length had a close correlation with the level of ploidy. Diploid plantlets (2n = 2x) had the average stomatal length of 33.50 µm when observed under an optical microscope at 100x magnification and corresponding to the peak at 70 FL in flow cytometric DNA histogram. In all identified polyploid plantlets, the stomatal lengths were greater than 40.12 µm. Moreover, flow cytometric analysis indicated that plantlets with stomatal lengths ranged from 40.12 to 50.00 µm were diploid-tetraploid mosaicisms represented by two separate peaks at 70 FL and 90 FL. Finally, samples treated with 4, 6, and 8 µM colchicine with treatment time of 48 h, and 60 µM oryzalin with treatment time of 24 h that had stomatal lengths ranged from 52.03 to 71.25 µm were determined to be tetraploid (2n = 4x) represented by a peak at 120 FL position.