The cells of living animals and plants each contain a number
of chromosomes. These are the location of the genes that control
the way the organism grows. When the organism reproduces itself,
copies of these chromosomes are transferred to the progeny. Irrespective
of the number of chromosomes that the organism possesses, together
they form the chromosome genome.
Wild Einkorn and some Goat Grasses are diploid
plants, the cells having 14 chromosomes, or seven matching pairs.
When any pollen and ovules are created, one chromosome from each
pair transfers to the new cell, giving seven chromosomes in each
of the pollen or ovule cells. If pollinated by the same species,
the pollen and ovule will have matching chromosomes. If they are
from two different species, the chromosomes will be unmatched
and any progeny would normally be sterile. However, in the case
of wheat hybrids, chromosome doubling or amphiploidy
occurred. Each chromosome could then combine with the replicate
to form matching paired chromosomes, similar to a normal pollination.
Naturally occurring amphiploidy and mutations have created many
tetraploid wheats with 28 chromosomes
and hexaploid wheats with 42 chromosomes.
Scientists are now able to create Synthetic
Hexaploid Wheats from tetraploid wheats and diploid goat grasses
by using colchicine to induce chromosome doubling. These SHWs
can then be used to diversify the wheat genome by transferring
selected genes, such as those responsible for grain yield or disease
resistance, from the diploid ancestors into modern wheat varieties.