Golden rice differs from its parental strain by the addition of three beta-carotene biosynthesis genes.
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The study raises the question of whether a vaccine that works against parental strains will also protect against their hybrid offspring, researchers said.
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And, the chromosomes that are lost from an aneuploid nucleus during its reversion to a euploid could be a mixture of those in the parental strain.
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As an example of independent assortment, consider the crossing of the pure-bred homozygote parental strain with genotype " AABB " with a different pure-bred strain with genotype " aabb ".
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A and a and B and b represent the alleles of genes A and B . Crossing these homozygous parental strains will result in F1 generation offspring that are double heterozygotes with genotype AaBb.
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Each new strain is given a unique number and registered with the U . S . EPA and allowances may be given for genetic modification depending on " its parental strains, the proposed pesticide use pattern, and the manner and extent to which the organism has been genetically modified ".