Question

A crop plant was susceptible to a fungal disease. However, a breeder found one plant that was resistant. Pure lines were constructed (L_Sus and L_R1) and crossed reciprocally. In both crosses the F₁ was resistant. After inter-crossing of the F₁ generation the F₂ segregated into 281 resistant and 219 susceptible plants.

A) Suggest a mode of inheritance and use a statistical test to support you conclusion.

B) What segregation is expected if the F₁ would have been backcrossed to L_Sus?

C) A second resistant plant, L_R2, was found and was also crossed reciprocally to L_Sus, here L_R2 x L_Sus gave a resistant F₁ and the following F₂ gave only resistant plants, whereas L_Sus x L_R2 gave susceptible plants. The F₂ generation gave a 3 susceptible: 1 resistant, (using a large sample) segregation. Explain this observation (i.e. the genotype of L_R2).

This is only the question. The last part c is the explaination of the observation.

Answer 1