Download or read book Identification and Characterization of a Maize (zea Mays L.) Gene Controlling Embryogenic Tissue Culture Response and Enhancement of Maize Transformation Systems written by Frank Lloyd McFarland and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize is one of the most economically important crops in the US and globally for food, feed, and biofuel production. Efficient production of regenerable, embryogenic tissue cultures of maize is necessary for both basic biological research and applied biotechnological approaches to maize genetic improvement. Efficient generation of regenerable cultures in maize is highly genotype-dependent and, historically, researchers in academia and industry have relied extensively upon a restrictively small number of genotypes amenable to conventional tissue culture. To identify the genetic basis for genotypic differences in culture response, a mapping-based approach was utilized. The tissue culture response trait from the regenerable maize inbred A188 was backcrossed into the recalcitrant inbred B73. An A188 genomic introgression spanning 3 Mb on chromosome 3 was strongly associated with regenerable tissue culture response. Three candidate genes were selected in the region based on their expression in A188 immature embryos and functional annotations of genes in the region. A screen of each candidate gene expressed under constitutive promoters identified a single candidate, Wox2a, which was found to induce somatic embryogenesis and embryogenic callus in B73.A complementary approach to mapping the A188 culture response trait was undertaken to map the genotype-dependent response of diverse maize lines to Wuschel2/Baby boom (Wus/Bbm)-mediated genetic transformation. Though Wus/Bbm-mediated transformation reduced recalcitrance of many lines through co-transformation with developmental regulators, strong trends of genotype-dependence were still observed. Ten diverse maize lines were screened to identify lines highly amenable to Wus/Bbm-mediated transformation. Transgenic plants/events were recovered from eight of the ten lines. One line, Gaspé Flint, generated transgenic events efficiently and at a wide range of embryo maturities. A Gaspé Flint x B73 introgression library was screened through Wus/Bbm-mediated transformation and Gaspé Flint introgressions associated with transformability were identified on chromosomes 1, 4, and 7. The scale of the transformation experiments necessitated isolation of thousands of immature embryo explants, for which a high-throughput method of embryo isolation (SIMPLE extraction) was developed. Methods for SIMPLE extraction, as well as optimized methods for Wus/Bbm-mediated and Wox2a-mediated maize transformation were developed to enable easy adoption these developing technologies.