Multifoliate Alfalfa: Its Causes and Effect

An increase in the leafiness of protein-rich alfalfa (Medicago) is possible not only through selection for a change in the size of the leaf blade. One of the first reports on the study of the phenomenon of the formation of additional leaflets (later called multifoliate) date back to the 1930s. This review mentions the main articles associated with the study of the trait. The leaf structure was described, and information on the correlations of multifoliate with the height, internodes, day length, and temperature was collected. The effect of germ plasm and methods of study on obtaining conflicting data was indicated. The assumptions initially made by researchers about an atavistic nature of the manifestation of the trait (and later about the presence of a recessive mutation with two additive genes regulating the expression) were considered. The method for finding an index of evaluation of multifoliate expression (proposed by Craig Sheaffer) and confirmation of a strong nature of inheritance of the trait in classical selection through a recurrent selection were demonstrated. In conclusion, the most significant genes and gene families that directly or indirectly affect the manifestation of multifoliate (including PALM1 and KNOX) were collected.