Genetic mapping of QTLs for tissue-culture response in plants

Plant regeneration from cultured tissues has been shown to be under genetic control in a number of plant species. Using quantitative trait loci (QTL) mapping technology, it has become possible to estimate the number of loci controlling genetic variation and to characterize their map position in the genome. With the use of different types of mapping populations such as recombinant inbred lines (RIL), F2 or doubled haploids (DH) it was possible to detect QTLs for tissue culture response (TCR). For the evaluation of TCR numerous parameters describing induction and regeneration steps were applied. However, the lack of consistency with respect to parameters used by different researchers sometimes makes comparisons between QTL studies complicated. Another problem frequently present in works dealing with QTLs for TCR is skewed distributions of the traits used for evaluating tissue culture capability, usually interpreted as the indication of a presence of major genes. The majority of QTL analyses of TCR-traits were conducted with monocots - rice, barley and maize. The number of QTLs detected for a particular characteristic of tissue culture capability ranged from 1 to 8. The percentage of phenotypic variation explained by a single QTL varied from 2.7 to 65.4%, with the values between ca. 6 and ca. 26 % being more common. Determination of molecular markers linked to a QTL of TCR provides valuable tools for biotechnological approaches aimed at improving plant regeneration capability.