MOLECULAR MARKERS APPLIED TO PLANT-TISSUE CULTURE

The last decade has witnessed successful applications of plant tissue culture techniques in several crops. During that same period, studies in plant molecular genetics have also grown exponentially. Molecular m arkers (isozymes, RFLPs, and PCR-based markers such as RAPDs) are now used to study many of the current limitations of tissue culture. They have been used to investigate mechanisms that underlie somaclonal vari ation in the nuclear, mitochondrial, and chloroplast genomes. One recu rrent problem with several tissue culture systems has been the difficu lty of determining the origin of regenerants. Molecular markers repres ent powerful tools to determine precisely the origin of plants derived from microspore or anther culture, protoplast fusion, and other tissu e culture studies where this information is important, With improvemen ts in tissue culture techniques, populations of doubled haploid lines have been produced in several major crop species. Doubled haploid popu lations have proven useful in the production of molecular maps and in tagging important agronomic traits. This review describes the use of m olecular markers to address fundamental and practical questions of pla nt tissue culture, and discusses the potential of improvements in mole cular techniques and new molecular markers such as SCAR and STS along with high-resolution mapping strategies.