In the tomato, Solanum esculentum , tall ( D - ) is dominant to dwarf ( dd ) pla
ID: 266641 • Letter: I
Question
In the tomato, Solanum esculentum, tall (D -) is dominant to dwarf (dd) plant height, smooth fruit (P-) is dominant to peach fruit (pp), and round fruit shape (O-) is dominant to oblate fruit shape (oo). These three genes are linked on chromosome 1 of tomato in the order dwarf-peach-oblate. There are 12 map units between dwarf and peach and 17 map units between peach and oblate. A trihybrid plant (DPO/dpo) is test-crossed to a plant that is homozygous recessive at the three loci (dpo/dpo). Progeny plants are grown with the results shown below.
Identify the mechanism responsible for the resulting data that do not agree with the established genetic map.
Progeny Phenotype Number Tall, smooth, round 473 Dwarf, peach, oblate 476 Tall, smooth, oblate 12 Dwarf, peach, round 8 Tall, peach, oblate 17 Dwarf, smooth, round 13 Tall, peach, round 0 Dwarf, smooth, oblate 1 1000Explanation / Answer
Answer. C. Inversion heterozygosity is suppressing the appearance of most of the chromosomes in this cross. There is loss in gametes due to failure of inverated region to synapse in heterozygosity inversion. The large heterozygosity inversion leads to less number of recombination.