@article{TEXTUAL,
      recid = {10301},
      author = {Carlson, Shawn R. and Rudgers, Gary W and Zieler, Helge  and Mach, Jennifer M and Luo, Song and Grunden, Eric and  Krol, Cheryl and Copenhaver, Gregory P. and Preuss, Daphne},
      title = {Meiotic Transmission of an In  Vitro<i>–</i>Assembled Autonomous Maize  Minichromosome},
      journal = {PLOS Genetics},
      address = {2007-10-19},
      number = {TEXTUAL},
      abstract = {<p>Autonomous chromosomes are generated in yeast (yeast  artificial chromosomes) and human fibrosarcoma cells (human  artificial chromosomes) by introducing purified DNA  fragments that nucleate a kinetochore, replicate, and  segregate to daughter cells. These autonomous  minichromosomes are convenient for manipulating and  delivering DNA segments containing multiple genes. In  contrast, commercial production of transgenic crops relies  on methods that integrate one or a few genes into host  chromosomes; extensive screening to identify insertions  with the desired expression level, copy number, structure,  and genomic location; and long breeding programs to produce  varieties that carry multiple transgenes. As a step toward  improving transgenic crop production, we report the  development of autonomous maize minichromosomes (MMCs). We  constructed circular MMCs by combining <em>DsRed</em> and  <em>nptII</em> marker genes with 7–190 kb of genomic maize  DNA fragments containing satellites, retroelements, and/or  other repeats commonly found in centromeres and using  particle bombardment to deliver these constructs into  embryogenic maize tissue. We selected transformed cells,  regenerated plants, and propagated their progeny for  multiple generations in the absence of selection.  Fluorescent in situ hybridization and segregation analysis  demonstrated that autonomous MMCs can be mitotically and  meiotically maintained. The MMC described here showed  meiotic segregation ratios approaching Mendelian  inheritance: 93% transmission as a disome (100% expected),  39% transmission as a monosome crossed to wild type (50%  expected), and 59% transmission in self crosses (75%  expected). The fluorescent <em>DsRed</em> reporter gene on  the MMC was expressed through four generations, and  Southern blot analysis indicated the encoded genes were  intact. This novel approach for plant transformation can  facilitate crop biotechnology by (i) combining several  trait genes on a single DNA fragment, (ii) arranging genes  in a defined sequence context for more consistent gene  expression, and (iii) providing an independent linkage  group that can be rapidly introgressed into various  germplasms.</p>},
      url = {http://knowledge.uchicago.edu/record/10301},
}