15 In cucumbers orange fruit color R is dominant over cream

15. In cucumbers, orange fruit color (R) is dominant over cream fruit color (r). A cucumber plant homozygous for orange fruit is crossed with a plant homozygous for cream fruit. The F1 are intercrossed (F1 individuals crossed with F1 individuals) to produce the F2. a. Give the genotypes and phenotypes of the parents, the F1, and the F2. b. Give the genotypes and phenotypes of the offspring of a backcross between the F1 and the orange-fruited parent. c. Give the genotypes and phenotypes of a backcross be- tween the F1 and the cream-fruited parent

Solution

RR (Orange homozygous) x rr(Cream homozygous)------>Rr (F1 Generation)

Rr x Rr -------------->1RR:2Rr:1rr (F2 generation)

(a) F1: Genotype= Rr , Phenotype= All Orange

F2: Genotype= 1:2:1, Phenotype 3:1 (3 Orange:1 Cream)

(b) Rr x RR -------> 2RR:2Rr , Genotype 1:1, Phenotype= All Orange

(c) Rr x rr ----------> 2Rr:2rr , Genotype 1:1, Phenotype= 1 Orange:1 Cream