Polygenic inheritance using character of carolia length of Nicotiana longiflora

• East and Emerson evaluate multiple factor hypothesis for explanation of the inheritance of true quantitative traits.
• Their studies demonstrates that the inheritance pattern of quantitative traits followed the predictions based on multiple factor hypothesis.
• They stated that a character is governed by several genes; the positive alleles of all the genes governing the trait are similar to each other in their action and that their effects are additive or cumulative in nature.
• This is the essence of multiple factor hypothesis.
• In 1961, East reported his studies on the inheritance of corolla length in Nicotiana longiflora , which presented a conclusive evidence for polygenic inheritance of this trait.
• He crossed two inbred lines with contrasting corolla lengths of 40 mm and 93 mm.
• The F1 from this cross was intermediate with a mean corolla length of 63 mm.
• In F2, a much larger variation for corolla length than that present in parents was observed.
• This variations was continuous as well.