Nano silver increases efficiency of strawberry micropropagation, disinfectant in Chrysanthemum micropropagation

Silver nano increases the efficiency of strawberry micropropagation

Strawberry (Fragaria × ananassa) of the Rosaceae family is one of the world's important fruit plants. Strawberries contain many minerals necessary for human nutritional needs such as vitamin C, vitamin B1, potassium, calcium and iron. In addition, strawberries also contain phenolic compounds such as anthocyanins, cinnamoyl glucose, cinnamoyl, ellagitannin, acid ellagic. In Vietnam, strawberries are grown a lot in Da Lat, with an area of about 190 hectares in 2018, and the output of over 2,200 tons.

The method of micropropagation, also known as in vitro propagation, is applied to strawberry plants to produce large numbers of disease-free and homogenous seedlings. Previous studies have often focused on growth regulators on in vitro progeny, callus formation, shoot growth and development, and completion of plant growth in vitro, without taking into account their use of materials and micronutrients in the process.

Scientists from the Central Highlands Scientific Research Institute studied the effects of silver nanoparticles on the sterilization of explants, the growth of in vitro explants (bud multiplication and rooting), as well as the accumulation of Ethylene gas during micropropagation of strawberry plants.

The results showed that leaf samples disinfected with silver nano solution (200 mg/L for 20 minutes) had higher efficiency in explant sterilization and shoot regeneration than using 1 g/L HgCl2. Silver nano stimulated the growth of shoots and seedlings, and shortened the time of root formation (4 days) compared with the control (no silver nano). Silver nano reduced ethylene gas accumulation in the culture flasks of shoots (0.66 ppm) and plants (0.06 ppm) compared with controls (1.77 ppm; 0.15 ppm; respectively). Combining silver nano with culture time (5; 10 or 15 days) increased acclimatization under nursery conditions. The young plants were cultured on MS medium (abbreviation for Murashige and Skoog medium, commonly used in plant tissue culture) supplemented with 0.5 mg/L silver nano for 10 days, 15 days and 60 days resulted in higher survival (93.33%), higher runner formation per plant (8.00 runner) compared with the seedlings under control conditions.

The study was published in the journal Plant Cell, Tissue and Organ Culture (PCTOC) 145: 393-403 (2021).

Effects of different concentrations of silver nano and different culture times on the growth of strawberry seedling after 60 days of planting in the nursery (Measurement: 5 cm)
A: 5 days rooting (control); B: 10 days rooting (control); C: Rooting 15 days (control); D: 5 days rooting (0.5 mg/L nano silver); E: 10 days rooting (0.5 mg/L nano silver); F: Rooting day 15 (0.5 mg/L nano silver)

Silver nano - disinfectant in chrysanthemum micropropagation

Microbial contamination (fungi, bacteria, etc.) is one of the difficult problems in micropropagation, reducing crop quality and loss of seed source. Therefore, sterilization of the culture medium is an important factor in the success of micropropagation. Research on using silver nano to sterilize the explants and culture medium to replace the autoclaving step in the micropropagation process of chrysanthemum plants gave positive results.

Research results show that 4-week-old ex vitro leaf samples sterilized with 250 ppm silver nano for 15 to 20 minutes for optimal surface sterilization efficiency. In addition, in the MS culture medium containing 4 ppm silver nano-silver sterilized the medium at 100% (no microbiological contamination) after 4 weeks of culture, the obtained seedlings gave the same results as the control environment (autoclaved) with 8 g/L agar and without the addition of silver nano. Chrysanthemum plants in the plastic box system (large scale) had higher activity of the antioxidant enzymes ascorbate peroxidase and superoxide dismutase, better adaptation, and the time to bud and bloom 1 week earlier than seedlings in control medium (autoclave). The successful use of nanosilver as a disinfectant and as a component of culture media reduces the cost of micropropagation and improves crop quality.

The study will be published in the journal In Vitro Cellular & Developmental Biology - Plant in 2021.

Mass production of chrysanthemums in plastic container culture systems

Translated by Phuong Huyen
Link to Vietnamese version