Different plant parts require different nutrients for their healthy development. So it is important to formulate a medium for plant cell growth which can support the requirements of different organelles of a cell as well as diverse cell types corresponding to each tissue type. Coconut water was used by Van Overbeek in 1941 allowed the culture of young embryos and other recalcitrant tissues including that of monocots, as well as callus cultures of numerous species, including a variety of woody and herbaceous dicots and gymnosperms as well as crown gall tissue cultures were established.
Also during this time it was recognized that cells in culture underwent a variety of changes, including loss of sensitivity to applied auxin or habituation as well as variability of meristems formed from callus, however it was during this period most of the in vitro techniques used today were developed. The basic plant tissue culture medium was developed by White and Gautheret by adding basic inorganic supplements and sugar source in 1943 & 1939 respectively. White formulated a media for growing carrot root culture. While Murashige & Skoog formulated MS media in 1962 by adding natural components to White’s basic culture medium.
The MS formulation is the most widely used medium, which was developed to ensure that no increase in cell growth in vitro were due to the introduction of additional salts from plant tissue extracts which were being tested at that time. Starting in the mid 1960 there was a dramatic increase in the application of plant tissue culture to various problems in basic biology, agriculture, horticulture, and forestry through the 1970s and 1980s. These applications can be broadly divided into five broad areas namely
a) Cell behavior
b) Plant modification and improvement
c) Pathogen free plants
d) clonal propagation
Natural components which can be added are fruit juices, yeast extract, malt extract, tomato juice etc, Plant tissue culture media consists of six macro elements, six macro elements, vitamins, amino acids, hormones & gelling agents.
According to International Association of Plant Physiology the compound required more than 0.5 mmol/l is called a macro element & the compounds which are required less than 0.5 mmol/l are known as microelements. Concentrations of the elements are measured and added in terms of mole rather than weight because, no matter how much the weight of the component may be, if it is added in moles, then the numbers of atoms (6.023 x 1023) for that component are same. Macro elements are used in the quantities of milli mole, where as micro elements are used in micro mole quantities.