Fig. 4.

Genotype distributions of five US Johnson grass populations near the Sb06g012260 gene. Among 480 plants sampled equally from GA, TX (2), NE, and NJ populations (Morrell et al. 2005), 81.6% and 88.2% were homozygous for the short-day haplotype (blue bars) at two terminal loci (423 nt, 27 bp intron indels), but only 1.1% and 8.0% at two internal loci (4,186 and 3 nt indels). Homozygosity for day-neutral alleles (green) is nearly absent from the GA sample (from the region where Johnson grass is thought to have been introduced to USA), but exceeds 10% in the two northerly populations (NE, NJ) where day-neutral flowering would be most advantageous, and is intermediate in the two TX populations.