5. F2 data (News Letter, March 23, 1937) indicated that pb4 is located between Y1 and Pl in chromosome 6. Backcross data obtained last summer, however, suggest rather close linkage of Y1 and pbx.
|F1 genotype||0||1||2||1, 2||Total|
|Y1 + Pl||170 132||- 2||47 35||1 1||388|
|+ pbx +||302||2||82||2|
Whether pbx is located to the right or to the left of Y1 can not be decided from these data. The white and yellow patches on plants obtained from backcrosses are considerably larger than those found on piebald plants from the F2, and are found not only on the leaves but also on the husks. This is attributed to the effect of modifiers rather than to environment.
G. A. Lebedeff