The observation that ca. 50% of the pollen collected from an F1 plant is non-viable is
consistent with the presence of a translocation in the genome of that plant, but this
observation alone does not prove the presence of a translocation. The production of ca. 50%
non-viable pollen by a heterozygous plant can be caused by a mutation in a male
gametophyte essential gene, a chromosomal inversion, or a chromosomal translocation
(Redei and Koncz, 1992). Further genetic characterization is necessary to differentiate
between these possibilities. For this reason, we performed genome-wide genetic mapping to
more directly test for the presence of translocations.