THE POTENTIAL OF TISSUE CULTURE TECHNIQUE IN NIGERIA
Population in developing countries is increasing daily, resulting in a consequent decrease in food production, leading to poor food security. This decreased food security could also be attributed to reduced agricultural land mass, decreased interest in agricultural activities, poor productivity of crops, etc. Many schemes have been employed to increase the quality and quantity of farm outputs, yet the population increase still surpasses the net food productivity. This is a great threat and danger to the survival of the human population. Therefore, there is a need to employ a means to increase food production, to meet up with the ever-growing population. One method that is used to numerically increase plantlets for planting, improve the quality of crops, and replicate progress made on crops is tissue culture technique.
TISSUE CULTURE TECHNIQUE
Tissue culture technique is the aseptic method of generating a complete plant from its tissue, in a nutrient medium. This method is carried out in a highly sterile laboratory because any contamination with microorganisms will affect the exposed and fragile tissue. The nutrient medium has every basic nutrient needed for the survival, growth, shooting, or rooting of the plants, depending on the stage and purpose of the exercise. Due to the requirement for the success of the exercise, the technique has not been fully integrated into the research laboratories of average research areas in developing countries. In developed countries, it has been used to advance agricultural activities.
THE BASIC REQUIREMENT FOR A TISSUE CULTURE LABORATORY
A laboratory for tissue culture technique should have the following.
- A sterile and protective laminar airflow cabinet to work on the plant tissue.
- A heat sterilizer to sterilize the metal equipment.
- autoclave for sterilizing the media.
- scalpels for resizing plant tissue.
- pH meter for determining the pH of the media.
- microwave for media preparation
- Microscope for viewing tissue samples.
- Pipettes for transferring volumes that are below the threshold of graduated cylinders (>1mL), as seen in plant hormones.
- waste container for putting wastes like surgical blades, plant tissue, etc., emanating from the processes.
- Magnetic stirrer that helps stir the medium while it heats up.
- Refrigerator for storing essential thermo-labile substances like vitamins, hormones, etc.
- Distillation plant for getting distilled water.
- Suitable containers like beakers, flasks, and graduated cylinders.
- Needles and syringes
- A warm, brightly lit growing area.
- A clean, well-lit, warm, and weaning greenhouse for acclimatization
- Scale for weighing dry media contents.
- Hygrometer to assist in measuring the humidity of the culture room.
- Thermometer helps determine changes in temperature.
STEPS OF TISSUE CULTURE TECHNIQUE
The different steps involved in carrying out micropropagation are listed below;
Collection of plant specimens: the method for specimen collection varies across plant species, the same way the specimen for tissue culture varies. Specimens are to be collected from less contaminated areas to reduce the bacterial load and taken to the laboratory to carry out the propagation exercise. Most specimens lose viability if they are left for a long period before they are processed and cultured, this implies that specimens are collected when the researcher is ready to use them. Also, ensure that the species are not stressed by transporting them comfortably from the collection zone to the laboratory, and keeping them in a clean and safe environment.
Surface sterilization: this is the most important aspect of tissue culture technique because all other steps depend on the success of this stage. If the plant tissue is not properly sterilized, it could lead to microbial contamination of the culture, hence, leading to cell death and decay. Also, improper exposure to the sterilant could kill the tissue. Proper study should be made for every plant tissue to know the suitable sterilant and sterilization protocol. Some possible sterilant are detergent, ethanol, NaOCL, benlate, HgCl2, U. V. Light, etc.
Initiation of shoot cultures: at this level, the major concern is to generate a pure culture. Sterilization can damage tissue when it is not properly handled, thereby, reducing the chance of survival by the tissue. Also, different plant species and tissues have different means of sterilization. For each tissue or tissue, different protocols may be applied. When the tissue is not properly sterilized, it will be contaminated, hence, impairing the success of the process. So, the media will be prepared to generate clean culture.
Multiplication of shoot-tip cultures: At this stage, a pure culture has been generated. The primary aim is to increase the number of shoots, thereby producing multiple shoots from a single shoot. Based on records, twenty shoots can be produced from a single culture. Based on the viability of the culture, some cultures could be divided into different portions and planted differently. To achieve the multiplication, a plant hormone called cytokinin is manipulated in the basal medium to induce shooting. Different plants could react differently to different concentrations, therefore there is a need to research the concentration that is very suitable for a particular plant spp and tissue.
Regeneration of plant roots: at this stage, the major aim is to induce roots in the cultures. This is because the plantlets will need it to access soil nutrients when they have been transplanted to the field. Without viable roots, plantlets from tissue culture will not anchor the soil or get nutrients from the soil, leading to the death of plants. To achieve rooting, plant hormones called auxin are manipulated. The more the viability of the plant’s root, the higher the chances of the plantlet to survive.
Weaning: after the roots are generated, the plantlets are carefully introduced to the environment in a weaning room. Acclimatization media is first prepared by sterilizing solid substrates and mixing them in ratios. Different substrates ranging from sawdust, river sand, soil, etc. are used with a ratio of 1:1 or 1:2, depending on plant species. If the plants are exposed to the harsh environment carelessly, the plants may die. Higher survival has been recorded when the plants are exposed in bits.
APPLICATIONS OF TISSUE CULTURE TECHNIQUE
- It helps in producing plants that are free from diseases.
- tissue culture technique assists in the mass propagation of plants.
- tissue culture technique helps in the transportation of plant species across locations.
- tissue culture technique increases plant yield and quality by combining different traits of plants into one plant
- It is used to generate plants without fertilization
- Seedless fruits can be generated as a result of tissue culture technique.
- In lack of time, it is applied to generate millions of plantlets.
CHALLENGES OF TISSUE CULTURE TECHNIQUE IN NIGERIA
- Inconsistent power supply
- High cost of reagents
- Lack of skilled manpower
- Lack of adequate laboratories
- Inadequate awareness of its relevance
- Insufficient or lack of encouraging government policy