The flow cytometry technique has currently been employed in various fields
of research, especially in measuring the 2C DNA of plants. The technique is also used
in modern biosystematics, speciation, evolutionary studies and in molecular breeding.
A large number of tissue culture raised ornamental and medicinal plants’ DNAs are
currently made and compared with field grown plants. Various factors influence the
quality of active nuclei isolation, which determines the success of accurate DNA
estimation. The importance of extraction buffer, reference standards, fluorochrome
dyes, and the process of gating is highlighted in order to understand various steps of
flow cytometry in measuring DNA. An array of compounds act as inhibitors to disrupt
fluorochrome binding to DNA, causing errors in estimating nuclear DNA content;
these compounds with their families are presented and summarized. Micropropagation
using shoot tips and nodal stems produces true-to type plants, while callus regenerated
plants show somaclonal variations – a process showing altered DNA. The role of flow
cytometry in investigating the genetic homogeneity of tissue cultured plant population
is therefore reviewed. The 2C DNA and genome size of a few medicinal and
ornamental plants such as Catharanthus, Allium, Rawolfia, Gladiolus, Caladium,
Zephyranthes from authors’ laboratory were measured and described. The intra-specific and inter-specific genome size and chromosome number variation with
reference to gene duplication and DNA sequence loss are discussed. The present
chapter, in general, discusses the applications of flow cytometry in field and tissue
culture grown ornamentals and medicinal plants.
Keywords: 2C DNA, Chromosome number, Flow cytometry, Genome size, Karyotype, Medicinals, Inter and intra-specific genome variation, Ornamentals.
