testcross — English Dictionary

Noun

1. The breeding of an individual with a phenotypically recessive individual, in order to determine the zygosity of the former by analysing proportions of offspring phenotypes.

   Examples

   More examples (2)

   The inbreds of groups 3 and 4 have a distinct difference in plant height, except for a few selections, presumably because of some difference in selection pressure at low- and high-stand densities. Group means for testcross performance showed more progress in group 4 than in group 3 because of a difference in the number of low-yielding genotypes in the two groups.

   You could determine its genotype by performing a testcross. If the plant were homozygous (TT), a testcross would produce all tall progeny (TT × tt → all Tt); if the plant were heterozygous (Tt), half of the progeny would be tall and half would be short (Tt × tt → 1/2 Tt and 1/2 tt). When a testcross is performed, any recessive allele in the unknown genotype is expressed in the progeny, because it will be paired with a recessive allele from the homozygous recessive parent.

Verb

1. To breed an individual in this manner.

Noun

1. a cross between an organism whose genotype for a certain trait is unknown and an organism that is homozygous recessive for that trait so the unknown genotype can be determined from that of the offspring

   Synonyms

   test-cross

   Broader terms

   hybridizationhybridisationcrossbreedingcrossingcrossinterbreedinghybridizing