The Prerequisite of the Success in Plant Tissue Culture: High Frequency Shoot Regeneration

Plant tissue culture is a term containing techniques used to propagate plants vegetatively by using small parts of living tissues (explants) on artificial growth mediums under sterile conditions. Explants regenerate shoots and roots, and consequently whole fertile plants under certain cultural conditions. Micropropagation is the production of whole plants through tissue culture from small parts such as shoot and root tips, leaf tissues, anthers, nodes, meristems and embryos. Micropropagation is the vegetative (asexual) propagation of plants under in vitro conditions and is widely used for commercial purposes worldwide [1-3].

Plant tissue culture techniques have certain advantages over traditional ones of propagation.
These are:

• Thousands of mature plants can be produced in a short time that allows fast propagation of new cultivars, 
• Endangered species can be cloned safely, 
• Large quantities of genetically identical plants can be produced, 
• Plant production is possible in the absence of seeds,
• The production of plants having desirable traits such as good flowers, fruits and odor is possible, 
• Whole plants can be regenerated from genetically modified plant cells,
• Disease-, pest- and pathogen-free plants in sterile vessels are produced, 
• Plants that their seeds have germination and growing problems such as orchids and nepenthes, can be easily produced, 
• Providing infection-free plants for mass production is possible.

Plant tissue culture is based on totipotency which means that a whole plant can be regenerated from a single cell on a growth medium. One of the main objectives of tissue culture studies is to obtain high-frequency shoot regeneration, which is also a prerequisite for an efficient transformation system and a clonal propagation of plants with attractive flowers and fruits in large scale for ornamental purposes. Specially the introduction of foreign genes coding agronomically important traits into plant cells has no meaning unless transgenic plants are regenerated from the genetically modified cell(s). 

It is known that some families and genera such as Solanacea (Nicotiana, Petunia and Datura), Cruciferae (Brassica and Arabidopsis), Gesneriaceae (Achimenes and Streptocarpus), Asteraceae (Chichorium and Chrysanthemum) and Liliaceae (Lilium and Allium) have a high regeneration capacity while regeneration in some other families such as Malvaceae (Gossypium) and Chenopodiaceae (Beta) is difficult. In order to increase the regeneration capacity of explant from the genotype of interest, we have to find answers to such questions as “Why do some genotypes regenerate easily?”, “What can be done to increase the regeneration capacity of explant?”.

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