testcross

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Test cross

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• test cross

From test +‎ cross.

• IPA^(key): /ˈtɛstˌkɹɒs/

testcross (plural testcrosses)

1. (genetics) 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.
   • 1967, W. A. Russell, A. H. Teich, Selection in Zea Mays L. by Inbred Line Appearance and Testcross Performance in Low and High Plant Densities:

     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.

   • 2012, Benjamin A. Pierce, Genetics: A Conceptual Approach, Macmillan, →ISBN, page 55:

     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.

testcross (third-person singular simple present testcrosses, present participle testcrossing, simple past and past participle testcrossed)

1. (genetics) To breed an individual in this manner.

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