Historical perspective and basic principles of plant tissue culture

Abstract

In 1902 Gottlieb Haberlandt proposed the idea to culture individual plant cells on artificial nutrient medium. Although he failed to culture them due to poor choice of experimental materials and inadequate nutrient supply, he made several valuable predictions about the nutrients' requirement for in vitro culture conditions, which could possibly induce cell division, proliferation and embryo induction. Tissue culture has now become a well-established technique for culturing and studying the physiological behaviour of isolated plant organs, tissues, cells, protoplasts and even cell organelles under precisely controlled physical and chemical conditions. Micropropagation is one of the most important applications of plant tissue culture. It provides numerous advantages over conventional propagation like mass production of true-to-type and disease-free plants of elite species in highly speedy manner irrespective of the season requiring smaller space and tissue source. Therefore, it provides a reliable technique for in vitro conservation of various rare, endangered and threatened germplasm. Micropropagation protocols have been standardized for commercial production of many important medicinal and horticultural crops. Somatic embryogenesis is an extremely important aspect of plant tissue culture, occurring in vitro either indirectly from callus, suspension or protoplast culture or directly from the cell(s) of an organized structure. Advantages of somatic embryogenesis over organogenesis include several practical means of micropropagation. It reduces the necessity of timely and costly manipulations of individual explants as compared to organogenesis. Moreover, somatic embryogenesis does not require the time-consuming subculture steps. As somatic embryos are the bipolar structures, they overcome difficulties with micropropagation of difficult to root species (mainly recalcitrant tree species). In addition to micropropagation, plant tissue culture is extensively used for the production of secondary metabolites through callus, suspension and organ culture.