Efficiency of liquid culture systems over conventional micropropagation: A progress towards commercialization

Abstract

The most common methods of micropropagation involve the proliferation of shoots via a semi solid system. While such semi solid systems have been moderately to highly successful in terms of multiplication yields, it has become increasingly important to improve productivity and reduce the time taken to multiply commercially important material. Micropropagation by conventional techniques is typically a labor intensive time taking means of clonal propagation. To overcome this, the use of shake cultures utilizing liquid culture medium has been promoted. The liquid medium allows the close contact with the tissue which stimulates and facilitates the uptake of nutrients and phytohormones, leading to better shoot and root growth. Continuous shaking promotes lesser expression of apical dominance which generally leads to induction and proliferation of numerous axillary buds. Further, with in the shake culture conditions, the growth and multiplication rate of shoots is enhanced by forced aeration, since continuous shaking of medium provides ample oxygen supply to the tissue which ultimately leads to their faster growth. Bioreactor provides a rapid and efficient clonal propagation system utilizing liquid medium to avoid intensive manual handling. Automation of micropropagation in bioreactors has been advanced by several authors as a possible way of reducing cost of micropropagation. Micropropagation in bioreactors for optimal plant production depends upon better understanding of physiological and biochemical responses of plant to the signals of culture microenvironment and an optimization of specific physical and chemical culture conditions to control the morphogenesis of plants in liquid culture systems.