Transmission Genetics of a × Backcross Populations.

Despite a "ploidy barrier," interspecific crosses to wild and/or cultivated sorghum (, 2n = 2x = 20) may have aided the spread across six continents of , also exemplifying risks of "transgene escape" from crops that could make weeds more difficult to control. Genetic maps of two BCF populations derived from crosses of (sorghum) and with totals of 722 and 795 single nucleotide polymorphism (SNP) markers span 37 and 35 linkage groups, with 2-6 for each of the 10 basic sorghum chromosomes due to fragments covering different chromosomal portions or independent segregation from different homologs. Segregation distortion favored alleles on chromosomes 2 (1.06-4.68 Mb, near a fertility restoration gene), 7 (1.20-6.16 Mb), 8 (1.81-5.33 Mb, associated with gene conversion), and 9 (47.5-50.1 Mb); and alleles on chromosome 6 (0-40 Mb), which contains both a large heterochromatin block and the gene. Regions of the genome that are recalcitrant to gene flow from sorghum might be exploited as part a multi-component system to reduce the likelihood of spread of transgenes or other modified genes. Its SNP profile suggests that chromosome segments from its respective progenitors and have extensively recombined in . This study reveals genomic regions that might discourage crop-to-weed gene escape, and provides a foundation for marker-trait association analysis to determine the genetic control of traits contributing to weediness, invasiveness, and perenniality of .