Quantitative Trait Loci (QTLs) Associated with Microspore Culture in Raphanus sativus L. (Radish)

Abstract

The radish is a highly self-incompatible plant, and consequently it is difficult to produce homozygous lines. Bud pollination in cross-fertilization plants should be done by opening immature pollen and attaching pollen to mature flowers. It accordingly takes a lot of time and effort to develop lines with fixed alleles. In the current study, a haploid breeding method has been applied to obtain homozygous plants in a short period of time by doubling chromosomes through the induction of a plant body in the haploid cells, in order to shorten the time to breed inbred lines. We constructed genetic maps with an F1 population derived by crossing parents that show a superior and inferior ability to regenerate microspores, respectively. Genetic maps were constructed from the maternal and parental maps, separately, using the two-way pseudo-testcross model. The phenotype of the regeneration rate was examined by microspore cultures and a quantitative trait loci (QTL) analysis was performed based on the regeneration rate. From the results of the culture of microspores in the F1 population, more than half of the group did not regenerate, and only a few showed a high regeneration rate. A total of five significant QTLs were detected in the F1 population, and five candidate genes were found based on the results. These candidate genes are divided into two classes, and appear to be related to either PRC2 subunits or auxin synthesis.

Natural Variation in Plant Pluripotency and Regeneration

“…This gene was upregulated in highly regenerable genotypes, and overexpression enhanced the performance of the recalcitrant RIL parent [ 121 ]. Composite interval mapping of the regeneration rate in microspore cultures of radish identified five QTLs and five corresponding candidate genes, homologous to PRC2 subunits and flavin-binding monooxygenases with a role in auxin biosynthesis and de novo root formation ( Table 3 ) [ 122 ]. Finally, two QTLs were discovered for protoplast regeneration in broccoli [ 123 ], and three unlinked genes were proposed to control shoot regeneration from leaf explants of wild potato ( Table 3 ) [ 124 ].…”