The fungus Melampsora lini causes a disease known as flax rust. Different strains of M. lini cause varying degrees of the rust d
isease. Conversely, different strains of flax are resistant or sensitive to the various varieties of rust. The Bombay variety of flax is resistant to M. lini-strain 22 but sensitive to M. lini-strain 24. A strain of flax called 770B is just the opposite; it is resistant to strain 24 but sensitive to strain 22. When 770B was crossed to Bombay, all F1 individuals were resistant to both strain 22 and strain 24. When F1 individuals were self-fertilized, the following data were obtained: 43 resistant to strain 22 but sensitive to strain 24
9 sensitive to strain 22 and strain 24
32 sensitive to strain 22 but resistant to strain 24
110 resistant to strain 22 and strain 24
Required:
Explain the inheritance pattern for flax resistance and sensitivity to M. lini strains.
Using the Mendelian approach to solve this question, we will understand that the mendelian approach has a pattern for inherited traits.
From the data set given, the total number of the population is:
43+9+32+110 = 194
However, their ratio are being calculated as follows:
43/194 = 0.22
9/194 = 0.05
32/194 = 0.16
110/194 = 0.57
After comparison with the Mendelian's approach, we realize that these results seem to be similar to the 9:3:3:1 ratio.
i.e.
3/16 = 0.18
1/16 = 0.06
3/16 = 0.18
9/16 = 0.56
The inheritance pattern obviously dictates that the flax experiment proceeds in the pattern found in the Mendelian's Approach and the resistance of the two different strains were arbitrated by two traits.
Why?: " Vestigial organs are physical structures that were fully developed
and functional in an ancestral group of organisms but are reduced
and unused in the later species."
