Morphological Genetic Markers in Plants

The review discusses the possible use of morphological genetic markers in plants. Definitions and terminology of such concepts as “marker,” “phenotype,” “genotype,” “epigenotype,” and “genetic marker” are given. The properties and distinguishing features of genetic markers are given. Some mutant marker forms are described and the feasibility of creating and utilizing collections of mutant marker forms for their practical use in genetics and breeding of agricultural plants is considered. It is indicated that the main sources of genotypic variation, the basis, reflection, and manifestation of which is polymorphism, including marker polymorphism, which manifests itself not only at the morphological but also at the biochemical or molecular levels, are mutations and recombinations. The role and significance of the first phenotypic genetic markers obtained from the fruit fly Drosophila by means of experimental mutagenesis methods is noted; it allowed T. Morgan and colleagues to establish the exact location of the genes in the linkage groups and use it as a basis to create the first genetic “maps” of Drosophila chromosomes. The main disadvantages of morphological genetic markers are that they are few in number and are influenced by environmental factors or depend on the stage of development of the plant or its organ or tissue in which they are found. In addition, they do not cover the entire genome, but are located in certain genomic loci, in which the genes are concentrated. This means that it is not possible to use morphological markers that do not cover the entire genome for the purpose of genotyping or establishing genetic distances. However, despite these exceptions, morphological markers still remain a relevant and very useful scientific tool in genetic and breeding practices. Many of these markers are genetically linked to important economically significant and agronomic traits, which makes it possible to drastically reduce the cost and simplify the production of new forms significant for genetics and breeding. It is noted that the problem of genetic analysis of economically valuable traits can be a field of activity for further methodological optimization and “bridge building” between classical and molecular genetics and plant selection, as well as other biological disciplines.