An organism’s specific genomic complement, or the DNA
sequences of all of its genes and intervening DNA
regions, constitutes its genotype.
Most genes are
present in a species in a number of different variants,
or alleles, which may or may not affect the function of
By scoring genetic locations within an
individual’s genome to know which alleles it has
inherited from its parents, the specific genotype can be
For example, if a particular gene confers
resistance to a disease, seedling plants can be screened
for the presence of this gene and only those with the
resistant allele of the gene can be grown for further
testing and propagation.
Such early genotyping and
selection can result in large savings in labor, land and
materials when screening large populations, particularly
when alternative phenotypic screens, such as infecting
all of the plants with the disease organism, are
labor-intensive and expensive.
enable the simultaneous testing of thousands of genes in
hundreds of individuals, making it feasible to select
for multiple traits in large plant populations.