Mapping Of Quantitative Trait Loci Involved In Shoot Regeneration In Different Arabidophsis Accessions

In vitro shoot regeneration is the basis of genetic transformation, gene function analysis and transgenic breeding in most plant species. The cloning and identification of key genes involved in shoot regeneration will be helpful for enhancement of regeneration frequency and efficiency of genetic transformation, and is pivotal to the construction of marker-free transgenic system. Recent studies showed that different Arabidophsis accessions show polymorphisms on plant physiology and development including seed dormancy and germination, plant morphology, flowering, self-incompatibility and response to environmental signals. The QTL mapping related to shoot regeneration ability were carried out preliminarily as yet.In this work, we adopt the common method to induce shoot regeneration in vitro by use of root explants. The shoot regeneration capacity cf172accessions were examined, and then the candidate loci involved in the regulation of regenerated shoot number were explored by QTL mapping strategy.Two accessions, Col-0and KY, showed extremely difference in shoot regeneration capacity. No visible differences were found in the origin and formation of callus between these two accessions. However, the overproliferation of KY accession callus in shoot-induction-medium (SIM) suggested their deficiency in cell differentiation ability. And KY callus were hypersensitive to auxin and cytokinin compared to Col-0. The real-time quantitative Reverse Transcription PCR (qRT-PCR) analysis showed that the expression of PIN1and LBD16was difficult to be detected in KY callus, implying that the lower expression level of PIN1and LBD16might contribute to the shoot regeneration deficiency of KY accession.Statistic results indicated that the shoot number of each callus is a quantative trait. Further,23pairs of molecular markers on Chromosome5linked to shoot number were screened out using the BSA method. Based on the results of primary QTL mapping, three QTLs were detected using F2population, whose variations were21.4%,27.37%and24.22%, respectively. Further, fine-mapping narrowed the QTL3to the interval of286Kb between marker23120631and MTI20.In conclusion, the defects of shoot regeneration ability of KY accession might result from deficiency in cell differentiation, hypersensitiveness to auxin and cytokinin and low expression level of PIN1and LBD16, and it is possible to find the key candidate gene(s) involved in the regulation of natural variation of shoot number per callus among Arabidopsis accessions by QTL fine mapping.