THE UNEXPECTED OCCURRENCE OF ALEU- 

 RONE COLORS IN F 2 OF A CROSS BE- 

 TWEEN NON-COLORED VARIETIES 

 OF MAIZE 



PROFESSOR R. A. EMERSON 

 University of Nebraska 



Before the Mendelian methods of analysis became 

 available, considerable wonder would doubtless have been 

 excited by the " mysterious" appearance in F 2 of one 

 colored grain — purple or red — to every five or six white 

 ones in case of a maize cross, both parents and F 1 of 

 which had only white grains. An occurrence of this 

 sort has recently been noted in one of my maize cultures 

 and the F 2 numbers are explained here as a trihybrid or 

 tetrahybrid ratio. The crosses in question were made 

 primarily for a study of size inheritance and fairly large 

 numbers have been grown. The varieties concerned are 

 two dwarfs of distinctly different types, Tom Thumb pop 

 and California Rice pop, and a tall type Missouri dent. 

 The facts with reference to aleurone color are these : Tom 

 Thumb pop, a "white" corn (i. e., having non-colored 

 aleurone), was crossed with Missouri dent, also a white 

 corn. Three generations of hybrid plants — four gener- 

 ations for aleurone and other endosperm characters- 

 have been grown without the appearance of any but 

 white grains. The same white-seeded Missouri dent was 

 also crossed with the white-seeded California pop. The 

 three hybrid generations grown to date have shown no 

 aleurone color. Furthermore, when the same white Tom 

 Thumb pop was crossed with the same white California 

 pop, only white grains appeared in F x . But both of the 

 two ears containing F 2 seeds— the only ones that have 

 been produced as yet— had a sprinkling of both purple 

 and red grains, too many to be explained as due to care- 

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