MICROPROPAGATION AND GENETIC FIDELITY ASSESSMENT OF HORTICULTURAL CROPS USING MOLECULAR MARKERS: A REVIEW

Abstract

Micropropagation is one of the important biotechnological methods used for the rapid and large scale propagation of elite genotypes of horticulture throughout the year. The method has some advantages over traditional methods of propagation such as rapid multiplication, production of disease-free plant materials, conservation of germplasms and propagation of plants which cannot be multiplied by seed or vegetatively. Nevertheless, the in vitro conditions may cause genetic and epigenetic changes that are referred to somaclonal variations. In commercial micropropagation, somaclonal variation is of particular importance because the main goal of clonal propagation is to produce genetically uniform plants. Morphology, biochemistry and cytology can provide useful information about uniformity; however, the use of DNA based molecular markers provides the most accurate way to determine genetic variation. A variety of marker techniques like Random Amplified Polymorphic DNA (RAPD), Inter Simple Sequence Repeat (ISSR), Simple Sequence Repeat (SSR), Amplified Fragment Length Polymorphism (AFLP), and Start Codon Targeted (SCoT), markers have been used to detect genetic fidelity of horticulture crops in micropropagation. Marker choice will depend on the particular crop, genetics, genomic information, facilities, cost and resolution requirements. Developments in next-generation sequencing, genome wide SNP screening, DNA methylation profiling and transcriptomics will make the application field of fidelity evaluation much wider than classical DNA fingerprinting. This review gives an overview of the principles of micropropagation, sources and origins of somaclonal variation, approaches to genetic fidelity evaluation, properties and use of molecular marker systems, applications of the technique in horticultural crops, factors affecting genetic stability, and technologies of high throughput quality control. The combination of optimized micropropagation techniques and molecular quality control systems may contribute to genetic stability and commercialization of micropropagated horticultural planting material.