Identification of TFA Genomic Regions that confer Amenability to Agrobacterium-Mediated Transformation in Barley

Different plant cultivars of the same genus and species can exhibit vastly different genetic transformation efficiencies. However, the genetic factors underlying these differences in transformation rate remain largely unknown. In barley (Hordeum vulgare), ‘Golden Promise’ is the most useful and well-studied cultivar for genetic transformation. By contrast, cultivar ‘Haruna Nijo’ is recalcitrant to genetic manipulation, although numerous genomic resources have been developed for this haplotype. Recently, we identified genomic regions of barley important for successful transformation with Agrobacterium, utilizing the ‘Haruna Nijo’ × ‘Golden Promise’ F₂ generation. A total of 3,013 ‘Haruna Nijo’ × ‘Golden Promise’ F₂ immature embryos were inoculated with Agrobacterium, and 60 transformants were obtained. These plants were genotyped using 124 genome-wide SNP markers. We observed significant segregation distortions from the expected 1:2:1 ratio toward the ‘Golden Promise’ cultivar in regions of chromosomes 2H and 3H, indicating that the alleles of ‘Golden Promise’ in these regions might contribute to transformation efficiency. We termed this region as Transformation Amenability (TFA) loci responsible for Agrobacterium-mediated transformation. The genomic regions identified herein likely include necessary factors (i.e. regeneration from callus) for Agrobacterium-mediated transformation in barley. The potential to introduce these loci into any haplotype of barley opens the door to increasing the efficiency of transformation for target alleles into any haplotype of barley by the TFA-based methods proposed in this presentation.