What is in vitro cultivation?
There is one area in the biological sciences that has proven benefits and has evolved rapidly since the last decades of the last century. It refers to the production of crops from isolated parts of plants, commonly referred to as tissue cultures. By this term is meant the cultivation in vitro (that is, in an artificial environment) under sterile conditions, of isolated cells, of individual structures or of various tissues and organs of plants. The method is used for the study, propagation and selection of plants. Initially introduced into experimental biology, the tissue culture method is rapidly entering practical crop production as well. It is based on the ability of plant cells to cultivate under artificial conditions separate from the plant from which they originate. Possibly it makes a unique property of a plant cell – namely, its “totipotency” – the ability to differentiate both the laid down and the ability for morphogenesis, which enable the regeneration of whole viable plants when the right conditions are provided for it.
The history of this method is interesting. The first attempts to cultivate tissue pieces and individual cells in an artificial medium (in vitro, “in a tube”) date back to the beginning of the twentieth century, when German scientists conducted laboratory experiments in this field. Haberland, a renowned botanist and plant physiologist, first conducted such experiments; Although not successful, it remains the first to clearly articulate the idea of growing individual plant cells in glass containers and on artificial media. This is, in fact, the first stage in the birth of this important science. Characteristic of the 1930s are not so much the practical successes as the search for optimal growing conditions, balanced nutrient solutions, suitable methods for inducing growth, division and differentiation of plant cells and tissues, as well as formulating leading ideas, have become the foundation upon which the subsequent development of this biological direction rests. After many attempts, the Frenchman Roger Gotree in 1933 successfully cultivated a parenchyma of roots and tubers and cambial tissues of woody plants on an artificial nutrient medium. Almost at the same time and independently, American Philip White has been successfully developing his method for the long-term in vitro cultivation of root meristem from houseplants. These two experiments marked the beginning of a rapid development of the tissue culture method, and respectively, the two scientists are rightly regarded as its founders.
Since the early 1940s, the method has been constantly evolving and refining. Technological advances in biology and biotechnology enable the full methodological and technical assurance of the experiments that are being carried out and allow their use as a daily practice, which is also the basis for the continued progress of agricultural science.
The main tissue cultures
The main tissue culture methods have been developed on a relatively small number of suitable sites – petunia, tobacco, carrots, alfalfa, as well as some wild plants. Of course, later the number of plant species involved in experimental in vitro development increased significantly. Methods for cultivation in artificial nutrient media of over 850 plant species are known and described. Experiments show that the conditions found to be necessary for one species do not always transfer successfully to other species, so that modifications of the basic methodology are required for each species – and often for individual varieties. In other words, experiments and practical applications in tissue cultures go hand in hand and many more discoveries are forthcoming in this field. Tissue cultures are used in basic general biological research as well as in breeding and crop production. The plant parts that are cultivated in vitro are: meristem, plant organs (embryo, flower buds, seedlings, bindings, seeds, pollen, roots, leaves, parts of stems), callus (which can be induced in any part of the plant) and cells. With respect to the prospects for using tissue cultures in the cultivation of Paulownia, the achievements in crop production and breeding are particularly important.
Fundamentals of micropropagation
The basic technological aspects of the micro-reproduction cycle are related to specific factors:
- varietal and species characteristics of the propagated plant
- deadline for taking the explants
- sterilization of the starting plant material
- composition of the nutrient media
- growing conditions
- adaptation of micro-plants to environmental conditions
It is of utmost importance to determine the exact timing of explants taking into account the physiological characteristics of the plant species. In Pylovnia, the introduction into sterile culture takes place during the active vegetation of the plant.
Crucial to the whole process is the surface sterilization of the plant material.
In the first phase of the process there is a marked increase in the vegetation peak. At this stage, in addition to the substances mentioned above, appropriate growth regulators must be present in the nutrient medium. Their concentration and the proportions in which they are invested are essential. However, the percentage of explants that adapt successfully depends not only on the nutrient balance, but also on the size and timing of their removal. In the multiplication stage (that is, accelerated reproduction), it is important to increase the concentration of specific growth regulators to induce proliferation of additional lateral buds. Under properly created conditions, these buds give rise to shoots (small plants) that form tuff. How many shoots will be present in a tuff depends on one quantity, which is of particular importance in the matter in question – the multiplication factor, which is different for each species. There are techniques that can help increase the value of the breeding factor. In general, the goal at this stage is to reach the required number of plants to allow the passage to the next phase – rooting.
Knowledge of each step
The precise knowledge of each step of the process of plant production in vitro allows the planning of each of the steps described. The laboratory at our disposal complies with all hygienic and technological requirements for proper micro-reproduction process. Good organization and conditions allow for programmed production so that no less than 200,000 new plants with qualities identical to the original one can be obtained from a single plant in 52 weeks. Our constant concern is that the crops are even – that is, all plants are in the same stage of development and grow with the same intensity. The method of micropropagation of Paulovnia requires considerable investment, strict adherence to the mandatory requirements, expert knowledge of the technology and care for its constant optimization. It is not easy to fulfill all of these conditions. That is why we are convinced that this is the right path, since this method of Paylownia propagation is 6 – 12 times faster than the traditional ones. Pailownia has a large multiplier – an advantage we cannot ignore. The healthy, pathogen-free, planting material we receive, the shortening of the initial stage of plant development, and the much smaller area required, are just some of the benefits we provide to our customers. By implementing this state-of-the-art so far method of vegetative propagation.