In tomato, red fruit R is dominant over yellow r, and purple stem P over green p. The traits assort independently. A mating produces red/purple = 145, red/green = 184, yellow/purple = 66 and yellow/green = 47 progeny. Which parental genotypes fit?
Combining stem classes, red:yellow is 329:113, approximately 3:1, indicating Rr × Rr. Combining fruit classes, purple:green is 211:231, approximately 1:1, indicating Pp × pp. Independent assortment combines these as RrPp × Rrpp, A. Sampling fluctuations explain why individual classes are not exact expected ratios.