Concepts and background of photoautotrophic micropropagation

Micropropagation is a method to produce genetically identical plantlets by using tissue culture techniques. Recent research revealed that chlorophyllous plantlets in vitro had high photosynthetic ability but that their net photosynthetic rates were restricted by the in-vitro environmental conditions, mainly the low CO ₂ concentration during photoperiod. Photoautotrophic micropropagation refers to micropropagation with no exogenous organic components (sugar, vitamins, etc.) added to the medium, and it has been developed along with the development of techniques of in-vitro environmental control. CO ₂ concentration, photosynthetic photon flux, relative humidity, and air current speed in the vessel are some of the most important environmental factors affecting plantlet growth and development; controlling these factors requires knowledge and techniques of greenhouse and horticultural engineering as well as the knowledge of physiology of in-vitro plantlets. Photoautotrophic micropropagation has many advantages with respect to improvement of plantlet physiology (biological aspect) and operation/management in the production process (engineering aspect), and it results in reduction of production costs and improvement in quality of plantlets. Feasibility of photoautotrophic micropropagation has been reportedly shown in both herbaceous and woody plant species. Photoautotrophic micropropagation will give a breakthrough in large-scale production of genetically identical, pathogen-free plantlets with vigorous growth and better overall quality and therefore, has a great potential to be introduced in transplant production and biotechnology research.