This may be
caused by the introduction of additional chromosome segments
from the donor or from linkage drag in the target chromosomes.
Each IL was expected to carry different lengths of introgressed
segments from Basmati into the Manawthukha background. In
order to reduce those heterozygous segments in BC4F2 we must use
single plant selection in the next self-pollinated generation to
obtain higher homozygosity percentages of the recipient genome